Antenna system

IS 2 289 151 T3

DESCRIPTION

Antenna system.

The present invention relates to an antenna system and, in particular, but not exclusively, to a group-in-phase antenna system having a plurality of antenna elements arranged in at least two subgroups. The antenna system is suitable for use in many telecommunications systems, but finds particular application in cellular mobile radio networks, commonly referred to as mobile telephone networks. More specifically, the antenna system of the present invention can be used with third generation (3G) mobile phone networks and in the Universal Mobile Telephone System (UMTS: Universal Mobile Telephone System). The invention also relates to a phase compensation apparatus for use in an antenna system.

Cellular mobile radio network operators generally use their own base stations, each of which includes one or more antennas. In a cellular mobile radio network, the antennas define the desired coverage area, which is generally divided into a number of overlapping cells, each associated with a respective antenna and base station. Each cell contains a fixed location base station that maintains radio communication with all the mobile radios in that cell. The base stations themselves are interconnected by other means of communication, usually fixed land lines arranged in a grid or mesh structure, which allows mobile radios throughout the entire cell coverage area to communicate with each other, thus as with the public telephone network outside of the cellular mobile radio network.

The antennas used in such networks are often composite devices known as phased array antennas comprising a plurality (usually eight or more), or group, of individual antenna elements or dipoles. The direction of maximum sensitivity of the antenna, that is, the direction of the main radiation beam or "viewer" of the antenna pattern, can be altered by adjusting the phase relationship between the signals fed to the antenna elements. This has the effect of allowing the beam to be directed or oriented to modify the coverage area of ​​the antenna.

In particular, phased group antenna operators of cellular mobile radio networks have a requirement to adjust the vertical radiation pattern (VRP), so as to alter the vertical angle of the main beam, also known as "tilt" as this has a significant effect on the coverage area of ​​the antenna. Adjustment of the coverage area may be required, for example, due to changes in the network structure or the addition or removal of other base stations or antennas in the cell.

Adjusting the angle of inclination of an antenna is known and is usually achieved by mechanical, electrical, or both. When the antenna tilt angle is mechanically adjusted, for example by mechanically moving the antenna elements themselves or mechanically moving the housing (or "dome") for the elements, this is known as "mechanical tilt" angle adjustment. When the angle of inclination of the antenna is adjusted electrically, for example by changing the time or phase delay of the signals fed to each element (or group of elements) in the group without physically moving either the housing for the elements, the elements themselves antenna elements or any other part of the antenna dome, this is commonly known as adjusting the "electrical tilt" angle.

The effect of adjusting either the mechanical tilt angle or the electrical tilt angle is to reposition the scope so that it points either above or below the scope set by conventional mechanical or electrical tilt mechanisms, and consequently increases or decreases the coverage of the antenna.

Until now, adjusting the mechanical or electrical tilt of a cellular radio antenna has been possible only by manually adjusting the tilt angle of the antenna itself, for example physically moving the antenna housing or dome in the case of mechanical tilt adjustment. or by mechanical adjusting devices to apply varying amounts of delay to antenna elements in the case of electrical tilt adjustment.

A disadvantage of employing such mechanical or electrical tilt adjustment methods is that the methods are difficult to perform and time consuming. Additionally, such adjustment methods result in the direction of the viewfinder being fixed at the adjusted angle of tilt for all transmitted and received signals, until such time as the angle of tilt is adjusted again. Consequently, the antenna cannot be shared by more than one operator unless the inclination required by each operator is identical. In practice this is rare and, in general, operators require an individual tilt angle in order to optimize antenna cell coverage for their particular base station deployment.

In any case, although the sharing of base stations, antennas and facilities is desirable, there are problems arising from doing so. In the UK, respective transmit / receive frequency bands are awarded to five 3G operators for transmission between mobile radios and base stations. The five transmit bands, or carrier frequency bands, are contiguous, as are the five receive bands, that is, there are no gaps between adjacent frequency bands. Consequently, unless complex and accurate filtering of signals is used by the transmitting and receiving apparatus associated with the antenna, the resulting overlap and interference of the signals has a detrimental effect on the performance of the system.

IS 2 289 151 T3

One known base station structure provides separate transmit and receive antennas, while another known system employs a duplexer to allow a single antenna to be used for both transmit and receive. These arrangements are suitable when only one operator is required to use the base station and antenna, but there are difficulties when more than one operator wishes to use the system.

A known solution for sharing base stations is for each operator to use a different antenna. In practice, this is achieved through the use of a shared antenna mast that supports a number of antennas, one for each operator. However, in order to avoid mutual interference, the antennas require adequate spacing and it may be necessary to increase the height of the mast, or it may be necessary to use a more robust structure, to enable the mast to withstand strong winds. This increases the weight of the mast, which, in turn, increases the cost of the mast. Also, places where a larger mast can be installed are difficult to find and planning permission or zoning problems can be encountered. Large masts also present environmental obstruction and are unsightly.

As a consequence, many cellular mobile radio network operators employ their own base stations with their associated masts and antennas. There is little site sharing and no sharing that occurs is limited to sharing the mast alone and not the antennas. The introduction of the so-called third generation (3G) mobile radio system will demand a greater number of base station locations. Thus, there is the possibility of difficulties in acquiring the necessary real state, and sharing places will be an increasingly attractive option.

It is an object of the present invention, therefore, to provide a method and / or apparatus that allows multiple operators of a base station site to share a common antenna while making it possible to adjust the tilt angle of the antenna so electrically and individually for each operator. It is a further object of the invention to make it possible for the angle of electrical inclination of the antenna to be adjusted remotely and to be different in transmission and reception.

In the following description, the term "antenna system" is used instead of the previous term "antenna" to describe a system that has an "antenna assembly", which is a group or series of antenna elements, and control means. to control signals supplied to the antenna elements in the antenna assembly.

According to a first aspect of the present invention, an antenna system is provided for use in the transmission and / or reception of at least two signals, whereby a first of said signals is generated in a first band of operator frequencies. by a first operator, and a second of said signals is generated in a second operator frequency band by a second operator, comprising:

an antenna assembly having an adjustable angle of electrical tilt, and including a plurality of antenna elements for transmitting and / or receiving said signals, wherein the antenna elements are mounted on an antenna carrier and are arranged in al least two subgroups, each subgroup including one or more of said elements, control means for electrically controlling the phase of signals transmitted and / or received by said antenna assembly, thereby controlling the angle of electrical tilt of said antenna assembly; and combining means for enabling said antenna assembly to transmit and / or receive essentially simultaneously a first of said signals at a first electrical tilt angle and a second of said signals at a second electrical tilt angle, the combining means being (730, 740) arranged to combine and / or divide signals transmitted and / or received by said antenna assembly and thereby enable signals associated with different angles of electrical tilt to pass through shared antenna elements (E1-En).

These first and second signals transmitted and / or received by the antenna assembly are used by different network operators and will thus have a different frequency. Advantageously, therefore, the antenna system allows the antenna assembly to be used by a plurality of operators.

Furthermore, when the electrical tilt angle can be adjusted from a location distant from the antenna assembly, each operator is able to adjust their cell coverage provided by the antenna assembly without visiting the base station site. Adjustment of the electrical tilt angle may be required, for example, to optimize coverage when the network is deployed, to optimize the network in response to measured performance parameters, daily in response to movement of urban switches, or periodically to meet the needs of a particular event, such as an exhibition or sports show.

In one embodiment, the antenna system is arranged to operate in a transmission mode, in which at least two signals are transmitted by the antenna assembly, the combining means being arranged to receive phase-adjusted signals from said control means and to essentially simultaneously transmit a first of said signals at a first electrical tilt angle and a second of said signals at a second electrical tilt angle. However, the apparatus is also preferably operable in a receive mode, in which the antenna assembly receives signals.

IS 2 289 151 T3

In a preferred embodiment, the apparatus includes first and second feed lines for applying first and second signals of a first polarization to and from the antenna assembly.

The apparatus further preferably includes third and fourth power lines for supplying third and fourth signals of a second polarization, opposite in sign to the first polarization, to and from the antenna assembly.

In a preferred embodiment, the apparatus includes a maximum of four power lines to supply signals to and from the antenna assembly.

The apparatus is advantageous in that multiple operators can use the system and transmit and / or receive signals in different operator frequency bands, each with different electrical tilt angles, if required, and this is achieved with use. of just four power lines, or just two if only one bias is required. Therefore, the apparatus is relatively simple and inexpensive, despite its ability to serve many different operators.

Furthermore, since a number of operators can share an antenna array, the requirement for additional base stations or antenna arrays is avoided.

For the purpose of this specification, the phrase "operator" or "user" is intended to mean an operator of a cellular radio network, as opposed to the site operator, who would be responsible for the antenna site.

For example, said control means include a first control arrangement associated with a first of said signals and a second control arrangement associated with a second of said signals, and the combining means may be arranged to receive the first of said signals from the first control arrangement and the second of said signals from the second control arrangement, and to supply a combined signal to said antenna assembly.

Preferably, the control means is arranged to electrically control the phase of signals supplied to at least one of said subgroups from a remote location from said antenna assembly, thereby controlling the angle of electrical tilt of said antenna assembly.

The control means may include a plurality of differential phase control units, each differential phase control unit being associated with a respective one of said operators of said antenna system.

Each of the differential phase control units may include first and second differential phase control subunits, said first differential phase control subunits being arranged to electrically control the phase of signals supplied to it for transmission by said antenna assembly and said second differential phase control unit being arranged to electrically control the phase of signals supplied to it, said signals having been received by said antenna assembly.

Preferably, the combining means includes first and second combining units, wherein each combining unit includes a respective transmitting combining network and a respective receiving dividing network having a plurality of inputs for connection to transmitting means of a corresponding plurality of transmission operators. said antenna system, said transmission combiner network being arranged to multiplex signals applied to said inputs by said transmitting means, thereby outputting a single multiplexed signal.

The transmission combiner network preferably includes a first transmission multiplexer arranged to receive at least two signals, each from a respective associated transmitter, and a second transmission multiplexer arranged to receive at least two signals, each from a respective associated transmitter, wherein each of the respective first and second transmit multiplexers is provided with a band pass filter arrangement for filtering signals received from a first of the respective transmitters associated with a pass band separated by a stop band from a band of passage of or of each one of the other of the respective associated transmitters.

Preferably, each band pass filter arrangement is arranged to generate a perfectly matched output signal (as defined herein).

The combined output signals from the band pass filter arrangement are fed into a combiner unit to generate a combined signal having a continuous, essentially perfectly matched frequency spectrum.

Preferably, said reception dividing network has a plurality of outputs for connection to receiving means of a corresponding plurality of operators of said antenna system, said receiving dividing network being arranged to divide a reception signal received from said antenna assembly to apply thereby said signal received to each of said receiving means.

IS 2 289 151 T3

In a further preferred embodiment, the combining means is arranged to generate phased output signals simultaneously for each of the plurality of operators, the antenna system further comprising a splitter arrangement for receiving said phased output signals and for dividing and distributing said phased output signals to the elements of the antenna assembly.

The divider arrangement is preferably arranged to distribute the signal intensity of said phase adjusted signals in an essentially uniform distribution.

In still a further preferred embodiment, the apparatus may include phase comparison means to ensure that the phase difference applied to the signals on the power lines remains essentially constant between said control means and said antenna assembly.

The measurement and phase adjustment process can be performed when the system is initially switched on, when it is required to change the angle of electrical inclination and / or periodically to compensate for thermal fluctuations in the power lines, for example every 10 minutes.

In one embodiment, the phase compensation means includes first and second assemblies disposed at opposite ends of the first and second feed lines.

Alternatively, the phase compensation means includes a phase measurement receiver module.

In an alternative embodiment, the apparatus may include phase compensation means for independently measuring, for a plurality of operator frequency bands, a transmission path phase difference measurement derived from the difference in phase difference between signals. supplied to antenna elements along a transmission path, and including feedback means to feed back said transmission path phase difference measurements to the control means. The control means preferably includes means for independently adjusting the phase of signals supplied to the first and second power lines for each of said operator frequency bands in dependence on the respective transmission path phase difference measurement, allowing with this will compensate for differences in said phase difference in different operator frequency bands.

For an antenna designed to transmit signal polarization only, the transmission path typically includes the first and second power lines for supplying transmission signals from the combining means to the antenna assembly, and respective first and second carrier lines, which are part of the antenna assembly, providing a means of connection between the first and second power lines and the antenna elements.

The apparatus may further comprise a Vector Measurement Receiver Module in the antenna assembly and may include means for extracting a part of said signals supplied to the antenna elements and means for combining said extracted portion with an oscillator signal having a frequency dependent on a frequency band selected by the operator, thereby determining the transmission path phase difference measurement for each operator frequency band.

Preferably, the Vector Measurement Receiver Module includes first and second phase comparing units to enable in-phase and quadrature phase difference measurements to be obtained, thereby determining an unambiguous phase difference measurement.

In a further preferred embodiment, the apparatus may include phase compensation means for measuring, for a plurality of operator frequency bands, a reception path phase difference measurement, derived from the difference in phase difference between received signals. in the antenna elements and transmitted along a reception path to the control means, and feedback means for feeding back said reception path phase difference measurements to the control means, and wherein said control means includes means for adjusting the phase of signals supplied to the first and second power lines for each of said operator frequency bands depending on the respective reception path phase difference measurement, with which it is possible to compensate for differences in said phase difference in different operator frequency bands.

This embodiment is particularly advantageous in that the phase difference differences between signals passing through the transmission path and signals passing through the reception path can be compensated independently, and furthermore they can be compensated for each operator frequency band independently.

The antenna assembly preferably includes oscillator means for generating a receive path calibration signal that is supplied through the receive path for the purpose of determining the receive path phase difference measurement in addition to the difference measurement. transmission path phases.

IS 2 289 151 T3

Preferably, the reception path also includes the first and second feed lines of the transmission path, but the reception signals normally pass through different amplifier and filter components for the transmission signals.

In a preferred embodiment, the oscillator means is a tone generator for generating a tone signal to be applied through the reception path.

For a selected operator frequency band, the tone signal preferably has an intermediate frequency between adjacent operator frequency bands, where one of the adjacent operator frequency bands is the selected operator frequency band.

Alternatively, the tone signal may fall within the operator's selected frequency band.

Preferably, the oscillator means is arranged to transmit a receive path calibration signal in a bandwidth of about 200 Hz.

For the purpose of this specification, the term "delay or phase shift" has been used for convenience of representation. The time delay can be achieved by changing the phase of the radio frequency carrier. As long as the phase shift is proportional to the frequency across the band, and has zero intercept distortion, the phase shift produces an essentially undistorted time delay. In this way the phase shift and the delay time are synchronous.

It will be appreciated that, for all aspects of the invention, in practice it may be desirable to transmit more than two of such signals at different angles.

The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 illustrates the vertical radiation pattern (VRP) of a known in-phase directional antenna assembly;

Figure 2 is a schematic block diagram of a known antenna assembly incorporating mechanical means for adjusting the electrical tilt angle;

Figure 3 illustrates a known third generation (3G) frequency division dual base station frequency allocation;

Figure 4 illustrates a known base station mast sharing arrangement;

Figure 5 illustrates a proposed antenna system according to a first aspect of the invention, involving the sharing of a single dual polarity antenna assembly by up to five operators;

Figure 6 illustrates a three sector, dual polarity antenna system incorporating three of the antenna systems of Figure 5;

Figure 7a is a block diagram of a proposed transmission combiner network for use in the antenna systems of Figures 5 and 6;

Figure 7b shows the frequency responses of filters used in the combiner network of Figure 7a;

Figure 8 is a block diagram of a preferred form of antenna system according to the invention (for an operator);

Figure 9 is a block diagram of an automatic phase control apparatus for use with the antenna system of Figure 8;

Figure 10 is a voltage-time scheme of signals emitted by mixers used in the apparatus of Figure 9;

Figure 11 is a block diagram illustrating the incorporation of the apparatus of Figure 9 into the system of Figure 8 and the use of the system by up to five operators;

Figure 12 is a block diagram of the antenna system of Figure 8 incorporating a Phase Measurement Receiver Module;

Figure 13 illustrates part of the Phase Measurement Receiver Module in more detail;

IS 2 289 151 T3

Figure 14 is a block diagram illustrating the incorporation of the Phase Measurement Receiver Module of Figure 12 into the system of Figure 8 and the use of the system by up to five operators;

Figure 15 is a block diagram for showing the components of an antenna for executing an alternative phase compensation method; Y

Figure 16 is a block diagram for showing the components of an antenna combiner unit for executing the alternate phase compensation method of Figure 15.

In the following description, the invention is explained in the context of an antenna system suitable for use in a cellular mobile radio network and particularly in the Universal Mobile Telephone System (UTMS). However, it will be appreciated that the invention is not limited to such use and that it may be equally applicable to other communication systems.

Figure 1 shows the vertical radiation pattern (VRP) of a conventional phased directional antenna assembly. The drawing is shown in side view and the antenna assembly is represented by point 1.

The VPR of antenna assembly 1 consists of a main lobe or "viewer" 2 that diverges in a vertical plane as it extends from the antenna assembly and represents the region of maximum radiation intensity of the beam radiated by the antenna assembly. . The VRP of the antenna assembly also includes several side lobes 4, representing regions of much lower radiation intensity, extending from the antenna assembly in directions that are approximately equally spaced around the antenna assembly in a vertical plane. The lobes 3 immediately adjacent to the viewer 2 are called the first upper and first lower side lobes, respectively.

The angle of tilt of the antenna assembly, when mechanically adjusted by physically moving the antenna elements and / or their housing or housing, is known as the "mechanical tilt" angle and is usually achieved by repositioning the viewfinder so that it points either above or below the horizon. When electrically adjusted, the tilt of the antenna assembly is known as "electrical tilt" and moves the sight line up and down by changing the time delay of signals delivered to groups of antenna elements, rather than by movement. mechanics of the elements themselves.

It will benefit the reader's understanding of the following description to note that both "electrical tilt" and "mechanical tilt" can be controlled and / or adjusted either by electrical or mechanical means, or by both, such that For example, mechanical movement of parts can be used to perform electrical phase adjustment (in which the antenna elements themselves are not physically moved) so that the position of the viewfinder is adjusted.

In Figure 2, the antenna assembly of a known antenna system incorporating an electrical tilt adjustment arrangement is shown in schematic block form generally at 10. The antenna assembly is a phase directional antenna consisting of a series of twelve elements or dipoles E1 to E12 that are arranged in three subgroups designated as A, B, and C. Each subgroup A, B, C includes four elements mutually connected in parallel, and is coupled to the output of the respective first, second and third delay devices 12, 14, 16. The delay devices 12, 14, 16 comprise conventional mechanisms of mechanical phase adjustment to adjust the phase of signals supplied to the subgroups. A radio frequency (RF) signal to be transmitted by the antenna is supplied to each of the delay devices 12, 14,16 from a common RF port or feeder 18.

The function of the delay devices 12, 14, 16 is to adjust the phase of the RF signal supplied to the respective subgroups A, B, C by a predetermined amount. The second delay device 14, connected to the central subgroup B, is a fixed delay device, arranged to shift the phase of the signal supplied to the subgroup B by a fixed amount. On the other hand, the first and third delay devices 12, 16, connected to subgroups A and C, respectively, are variable delay devices, each of which is operable to shift the phase of RF signals supplied to subgroups. A and C, respectively, in a variable amount.

The first and third delay devices 12,16 can apply phase shifts of, typically, between 0 and ± 45 ° for an RF signal supplied to subgroups A and C, and each is adjustable by means of an adjustment arrangement. mechanical. The mechanical adjustment arrangement 20 includes means, respectively shown at 22, for reversing the direction of the phase shift applied to the signal by the third delay device 16 compared to that applied by the first delay device 12. Thereby, the phase shift applied to the RF signals by the first and third delay devices 12, 16 is of equal magnitude, but of opposite polarity. In other words, if the first delay device 12 shifts the phase of the signal supplied to subgroup A by + 45 °, then the third delay device 16 shifts the phase of the signal supplied to subgroup C by -45 °. Since the second delay device 14 is a fixed delay device, in practice a phase shift is applied to the signal supplied to subgroup B which is the average of the offsets applied by the first and third delay devices 12, 16.

IS 2 289 151 T3

The electrical tilt angle of such an antenna array typically varies by ± 5 ° to ± 45 ° of phase shift per subgroup. This provides a tilt sensitivity of approximately 18 ° phase shift per degree of electrical tilt. In this example, therefore, since the RF signals supplied to subgroups A and C differ by 90 °, the electrical tilt of the antenna assembly is approximately 5 °. The direction of the electrical tilt of the antenna assembly depends on the polarity of the phase shift applied to the signals supplied to the subgroups. When the signal applied to the upper subgroup (in this case subgroup A) has a positive phase and the lower subgroup (in this case subgroup C) has a negative phase shift, the electrical tilt angle will be positive, that is, by above the normal line of the viewfinder. For opposite polarity phase shifts, the electrical tilt angle will be negative.

The antenna assembly of Figure 2 suffers from the disadvantage that manual adjustment of the mechanical adjustment arrangement 20 requires adjusting the phase shift applied by the first and third delay devices 12, 16 in order to vary the angle of rotation. electrical tilt of the antenna assembly. Furthermore, the phase of the signals applied to each antenna element cannot be adjusted individually.

Figure 3 shows the Third Generation Frequency Division Duplex (3G FDD) frequency bands awarded by the United Kingdom (UK) Radio Communications Agency for use by UK 3G network operators. Each of the five UK operators is licensed to use a specific first portion, or sub-band, of the allocated spectrum for transmission, for example from a base station to a mobile radio within the network, and another of that portion for reception. , for example from a mobile radio to a base station. These subbands are designated as Licenses A, B, C, D and E. The total spectrum ranges from 2110.3 MHz to 2169.7 MHz for base station transmission and from 1920.3 MHz to 1979.7 MHz for base station reception. Although there are unallocated frequencies known as guard bands (not shown) at the boundaries of these frequency ranges, there are no gaps between the individual subbands A, B, C, D, and E, which are therefore contiguous. .

Due to the problems associated with sharing a common antenna by network operators using adjacent subbands, base station sharing is often achieved through the structure illustrated in Figure 4. Structure 60 allows five network operators share a base station site with a respective transmit / receive antenna that is provided for each operator per sector. The result is a total of five antennas (Antennas A, B, C, D and E) for each sector, which are mounted on a common base station mast 62, each antenna being mounted on the mast 62 at a different height, or at the same height and adequately separated. Each antenna has a respective transmitter / receiver apparatus 64A to 64E. The height of the mast 62 must be greater than that required for a single antenna in order to accommodate all five antennas. As a consequence, the strength of the mast 62 must be increased, for example to enable the mast to withstand strong winds, which, in turn, increases the weight and cost of the mast. Also, not all sites are capable of accommodating a larger mast and difficulties are often experienced in obtaining planning permits from local authorities. Large masts are also unsightly and annoying and can be environmentally unacceptable in some places.

Figure 5 shows a proposed combiner unit to reduce the number of antennas required to support five network operators from five to one. The combiner unit, shown generally at 70, comprises a transmit combiner network 72, a receive splitter or demultiplexer network 74, and a duplexer unit 76. The five network operators have respective TxA to TxE transmitters connected to the transmission combiner network 72, and RxA to RxE receivers connected to the receive splitter network 74. The networks 72, 74 are connected through the duplexer unit 76 to a shared antenna assembly 78.

Transmitters TxA to TxE generate RF signals that are combined in transmission combiner network 72 and passed through duplexer unit 76 to antenna assembly 78 for transmission. The signals received by the antenna assembly 78 from remote radio mobiles (not shown) are fed from the antenna assembly 78 through the duplexer unit 76 to the receiving splitter or demultiplexer network 74.

In Figure 6, the structure of Figure 5 is extended to include three separate antenna assemblies 78a, 78b, 78c to form a so-called "Three Sector Antenna Assembly", in which each antenna assembly is arranged to provide coverage. of horizontal cell in 120 degrees of arc (or one third of a circle), such that, together, the antenna assemblies 78a, 78b, 78c provide cell coverage in the entire 360 ​​degrees. In this embodiment, each antenna assembly 78a, 78b, 78c is a dual polarity antenna assembly. The use of dual polarity antenna assemblies is well known in cellular radio systems. Each antenna assembly 78a, 78b, 78c consists of a stack of cross dipole elements, a first series or group of elements at an angle of + 45 ° to the vertical, and a second series or group of elements at an angle of - 45 ° from the vertical. The groups for each polarity are effectively separated electrically, with individual combiner units 70a, 70b being provided for each group. Each antenna assembly is thus connected to the respective first and second combiner units 70a, 70b, which have the shape of the combiner unit 70 of Figure 5. Combiner units 70a, 70b are identical for both polarities, since they are the connections to them from the transmitters and receivers of the operators.

Considering, for clarity, only the positive polarity components of the system, each of the TxA to TxE transmitters of the network operators is connected to a respective input of each of the combiner networks

ES 2 289 151 T3 transmission 72 in the three combiner units 70a, 70b, 70c, of positive polarity. The signals supplied from the transmitters are passed from the transmission combiner network 72 through the duplexer unit 76 to the respective antenna assembly 78a, 78b, 78c for transmission.

Similarly, each of the network operators RxA to RxE receivers is connected to a respective output of each of the receive splitter networks 74 in the three positive polarity combiner units 760a, 70b, 70c. The signals received by an antenna assembly 78a, 78b, 78c are passed through the associated duplexing unit 76 to the reception splitter network 74 which divides the received signal into five equal parts and applies it to the receivers RxA to RxE.

The negative polarity components of the system are connected in a similar way. It can therefore be seen that five operators are capable of simultaneously using the system, requiring only one antenna set when using an omnidirectional antenna set or three antenna sets when using a three sector system. Previous systems required five separate antenna assemblies per sector or fifteen antenna assemblies for a three sector system.

Combiner unit 70 of FIG. 5 can suffer from several disadvantages. First, the transmission combiner network 72 may include components that introduce significant signal losses to the system. Signal losses reduce the transmission interval of the system. Amplifiers can be added to remedy signal loss, but this suffers from the inability to handle the power required for transmission in all five frequency bands simultaneously with adequate linearity, instantaneous bandwidth, and efficiency, along with the required reliability.

The introduction of band-pass filters in the transmission combiner network 72 has been suggested to reduce the power output required by the amplifier, in which the transmission combiner network 72 has a set of parallel band-pass filters that act in combination as a transmit multiplexer. The band pass filters filter the signals from the respective transmitters TxA to TxE, after which the signals are multiplexed to a common output line and routed to duplexer unit 76 and antenna assembly 78. The passband of each filter is selected so that it is as close as possible to the frequency band allowed to the respective operator. Such an arrangement, however, further increases the signal loss in the system due to the shallow roll-off of most band-pass filters and the resulting overlap of sub-bands, and reduces the isolation between TxA transmitters. to TxE.

An improved transmission combiner network is generally shown with 200 in Figure 7a, for use in the combiner units shown in Figures 5 and 6. The transmission combiner network 200 incorporates first and second transmission multiplexers 222ABE and 222CD. The first transmit multiplexer 222ABE is arranged to receive transmit signals from up to three transmitters 224A, 224B, 224E and filters them into respective filters 226A, 226B, 226E. The second transmit multiplexer 222CD is arranged to receive transmit signals from up to two additional transmitters 224C and 224D, and filters them into respective bandpass filters 226C, 226D.

The filtered output signals from band-pass filters 226A, 226E are combined into a first filter output (combined output signal 228X) and those from band-pass filters 226C, 226D are combined into a second filter output. filter (combined output signal 228Y). The 228X, 228Y signals from the filter outputs are combined into a two-input 3dB passive combiner 232 having two 232X, 232Y input ports and one 232Z output port. The combined output signal from output port 232Z is ​​then fed, as shown in FIG. 5, through duplexer unit 76 to associated antenna assembly 78.

Referring now also to FIG. 7b, respective passbands 240A through 240E of the five filters 226A through 226E are as shown. Passbands 240A to 240E have the same nominal maximum (although passbands 240C and 240D are shown lower relative to the others for clarity) and it can be seen that the bandwidths are not the same. As shown on a 242 frequency scale, five licensed frequency bands 242A to 242E comprise frequency bands 242A and 242B immediately adjacent to frequency band 242C, and frequency bands 242B and 242E immediately adjacent to frequency band 242D. . This results in two groups of non-adjacent frequency passbands 242A / 242B / 242E and 242C / 242D, which, as shown in Figure 7a, are associated with different transmission multiplexers 222ABE and 222CD, respectively.

Because the filter pass bands in each 222ABE or 222CD transmit multiplexer are separated by stop bands that prevent significant bandpass overlap, the 228X signals exiting filter 226A, for example, will reach only transmitters 224B and 224E, through filters 226B and 226E, highly attenuated and will be negligible for most purposes. The same applies to coupling between other pairs of transmitters within a single transmit multiplexer, 222ABE or 222CD, and thus to filters 226A to 226E. The attenuation provided by filters 226A to 226E isolates the transmitters from other signals, at the outputs of which signals 228X or 228Y are generated, as appropriate, and consequently at those outputs the signals 228X or 228Y are "perfectly matched" . The term "perfectly matched" is intended to mean that, because the passbands of the respective filters do not overlap, the electrical impedance of the multiplexers 22ABE and 222CD over the filter passbands remains essentially constant. This allows input signals from transmitters 224A to 224E to pass through a 222ABE or 222CD multiplexer for

ES 2 289 151 T3 provide a 228X or 228Y output signal with minimal ("perfect") distortion, thus performing the desired combining function. When the filter passbands overlap, the impedance of the passbands is not constant, so the signals that appear at the multiplexer output are distorted (“imperfect”). To combine the two signals 228X and 228Y while inhibiting undesirable interactions between transmitters 224A to 224E, combiner 232 is used. The combiner is a two-input 3dB passive bandwidth component and provides good signal isolation of at least 20dB between its two-input 232X and 232Y ports, respectively, regardless of the frequency separation of the signals at those ports. . This allows signals that are adjacent in frequency to be combined without allowing appreciable undesirable transmitter coupling between them. Therefore, the groups of signals at 228X and 228Y combine in a linear fashion, without an unacceptable degree of mutual interaction, and appear at the output of combiner 232 as a continuous frequency spectrum essentially perfectly matched.

Although there is an inherent signal loss between the input and output ports 232X to 232Z of the combiner 232, this is significantly less than the loss imposed by a transmitting combiner network that relies entirely on passive waveband components. The two-stage combination solution described with reference to Figure 7a provides a more efficient passive transmitter combination network than conventional structures and avoids the need for a multi-carrier linear power amplifier.

Therefore, the arrangement allows operators in both adjacent and non-adjacent bands to share a base station antenna array. Expensive multi-frequency power amplifiers are not necessary because the transmission combiner network 200 has reduced losses compared to that shown in Figure 5. Furthermore, the arrangement avoids the inherent overlap of filter pass bands in the network. transmission combiner 72 of FIG. 5.

The minimum number of transmission signals that can be used in an arrangement similar to the transmission combiner network 200 of FIG. 7 is two, the two signals being connected, through respective separate filters, to the passive combiner 232 of 3dB. If there are only two transmitters in adjacent frequency bands, there is no need for multiple transmission of signals in a multiplexer such as 222CD before feeding combiner 232. If there are two signals that are not adjacent in frequency, they can be combined using a multiplexer 222 and fed to a duplexer without going through a combiner such as 232, thus reducing signal loss. With three transmit signals, of which at least two are in adjacent bands, two would be combined in multiplexer 222 and the third would be fed directly to combiner 232. However, if the three non-adjacent frequency bands A, B, and E were to be combined, only one 222ABE multiplexer would be required and its 228X output would be fed directly to the duplexer without going through the 232 combiner. Four or more signals require two groups of two or more non-adjacent signals, to be multiplexed each group together before combining with another group. When fewer than five transmitters are combined, any unused inputs to multiplexers 222 would normally be terminated on one load. Alternatively, unused frequency filters 226 can be omitted from the multiplexer, thereby reducing cost, size, and weight.

The transmission combiner network 200 is described in more detail in copending patent application number 0108456.5, the contents of which are incorporated herein by reference.

The antenna system of Figure 6 allows up to five network operators to share a common antenna assembly. However, as described above, there is no need for an antenna system that not only allows several network operators to use a common antenna assembly essentially simultaneously, but also provides the stability for electrical adjustment independent of the angle of rotation. electrical tilt of the antenna assembly by each operator, and preferably from a remote location from the antenna assembly itself.

A preferred form of antenna system according to the invention is shown in Figure 8 generally at 700. In this embodiment, antenna system 700 comprises an antenna assembly 702 having a total of twelve antenna elements E1-E12 arranged in three subgroups 700A (E1-E4), 700B (E5-E8) and 700C (E9-E12). The electrical tilt angle of the assembly 702 can be adjusted by control means in the form of a Tilt Combiner Unit (TCU), as represented by the dotted line 704 and described in more detail below. Whats Next.

First and second input signals Sa and Sb, for transmission by antenna assembly 702, are supplied to antenna elements E1-E12 via first and second input carrier lines 720, 722, respectively. Antenna assembly 702 includes first and second primary splitter units 716A, 716B powered by a respective one of the first and second input carrier lines 720, 722. Each of the divider units 716A, 718B produces two output signals of essentially equal intensities / powers. A first output signal from the first divider unit 716A is supplied to a phase shift unit 717A to apply an additional phase shift, typically between -45 and -60 degrees, to the signal from the primary divider unit 716A. The phase-shifted output signal is provided to an additional divider unit 716C, which serves to divide the input signal it receives into two signals of essentially equal strengths. The two output signals from the additional divider unit 716C are supplied to a respective additional divider unit 716D, 716E, each of which divides the signal it receives into two output signals of essentially equal intensities. The output signals of the additional divider units 716D, 716E are fed to a respective one of the elements E1 to E4 of the first subgroup 700A. Each element E1 to E4 has an associated adjustment arrangement

ES 2 289 151 T3, 151E1, 151E2, 151E3, 151E4, respectively, to provide additional and individual means of adjusting the phase shift of signals supplied to each element, as further described below. In receive mode, the signals are combined on the first and second carrier lines by a reverse path through the same devices.

It will be appreciated from the preceding description that the divider arrangement 716A, 716C, 716D, 716E is configured such that each of the output signals to elements E1 through E4 of the first subgroup 700A receives a signal of essentially the same intensity.

A second output of the divider unit 716A is provided to a further divider unit 719A, which divides the input it receives into a first output signal that is provided to an input (A) of a first quadrature hybrid combiner unit 726A and a second output signal that is provided to an input (A) of a second quadrature combiner unit 726B.

The second divider unit 716B provides a first output signal to a further divider unit 719B, which divides the input it receives into two signals of essentially the same intensity, one of which is provided to a second input (B) of the first quadrature combiner unit 174A and the other of which is provided to a second input (B) of the second quadrature combiner unit 174B.

Each of the first and second quadrature combiner units 726A, 726B provides first and second output signals to the two elements of the central subgroup 700B: the first quadrature combiner unit 726A provides signals to elements E5 and E6 and the second combiner unit 726B in quadrature it provides signals to elements E7 and E8. The first and second quadrature 726A, 726B combiner units ensure that the phase of signals provided to elements E5 to E8 are the average of the phase of the signals on the input carrier lines 720, 722. For example, when the supplied power decreases to element E5, the power supplied to element E6 increases, so that the total power supplied to elements E5, E6 remains essentially constant.

A second output signal from the second divider unit 716B is passed through a second phase shift unit 717B, which applies a phase shift of +45 degrees (i.e., opposite polarity to the shift unit of phase 717A) to a divider unit 716F. The divider unit 716B divides the input signal it receives into two output signals of essentially equal intensities, which are in turn divided into two more signals by additional divider units 716G, 716H. The four output signals of the divider units 716G, 716H are provided to a different one of the elements E9 to E12 of the third subgroup, through a respective additional phase adjustment arrangement 150E9 to 150E12.

The central subgroup 100B is thus powered by an arrangement of quadrature hybrid units, with the result that the power in the central subgroup is essentially 50% of the total power of the group or series, both with respect to transmission and reception. of signals. For the series as a whole, the phase of the signal generated in transmission will be the average of the phase supplied by the two input carrier lines 720, 722, with a phase shift of -45 degrees. Similarly, a signal received by the central subgroup 700B will be intermediate to the phases received by the other two subgroups 700A, 700C, offset by -45 degrees.

The input ports 712, 714 on the antenna assembly are each connected to an output port 752, 754 on the TCU 704 through respective feed lines 756, 758. The TCU 704 includes first and second combiner units 730, 740, similar to unit 70 shown in Figures 5 and 6, with the output of each combiner unit 730, 740 being connected to output ports 754, 752, respectively.

The TCU 704 also includes phase control means in the form of a differential phase control unit (DPCU), generally referred to at 750. The DPCU 750 comprises a phase control subunit. transmit differential, indicated by dotted line 750a, and a receive differential phase control subunit, indicated by dotted line 750b. Transmission differential phase control subunit 750a comprises an input splitter unit 725a, an input to which is connected to the output of a single RF port 726a associated with the transmitter (not shown) of a first network operator 760. . Divider unit 725a has two outputs, each of which is connected to an input of a respective first and second adjustable delay units (referred to below as a "transmit phase adjuster") 760a , 762a. In this way, the signal to be transmitted by each network operator is divided into two signals of equal powers by the input divider unit 725a, and these two signals are then subjected to differential phase shift by means of the networks of phase shift 760a, 762a.

The first transmission phase adjuster 760a is connected by its output to an input of the transmission combining network 734 of the first combining unit 730. The second transmission phase adjuster 762a is connected by its output to an input of the combining network transmission 744 in the second combiner unit 740.

The receive differential phase control subunit 750b comprises an output multiplexer unit 725b having two inputs and one output. The output of the multiplexer output unit 725b is connected to the input of a single RF port 726b associated with the receiver (not shown) of the first network operator 760.

IS 2 289 151 T3

Each of the two inputs of the output multiplexer unit 725b is connected to the output of a respective first and second adjustable delay unit (hereinafter "receive phase adjuster") 760b, 762b. The first receive phase adjuster 760b is connected by its input to an output of the demultiplexer 746 of the second combiner unit 740. The second receive phase adjuster 762b is connected by its input to an output of the demultiplexer 736 of the first combiner unit.

In operation, a signal to be transmitted by the antenna system 700 is fed from the RF port 726a of the first operator 760 at the base station to the input of the input splitter unit 725a. The input divider unit 725a divides the signal into two output signals of equal intensities and supplies a divided signal to each of the first and second transmission phase adjusters 760a, 762a of the transmission differential phase control subunit 750a.

The first and second transmit phase adjusters 760a, 762a are operable by the network operator to apply a variable delay to the signal supplied to the network operator, thereby adjusting the phase of the signal within a range of ± 45 ° . The transmission phase adjusters 760a, 762a are differentially controlled such that, if the first transmission phase adjuster 760a is arranged to apply a positive phase shift to the RF signal applied thereto, the second transmission phase adjuster Transmission 762a is arranged to apply a negative phase shift to the RF signal applied thereto, and vice versa. This arrangement has the advantage that the amount of delay variation required by each transmission phase adjuster is half that required by an alternative arrangement in which one delay device has a fixed delay value and the other increases or decreases. the delay relative to the fixed value. However, each transmission phase adjuster 760a, 762a is arranged to adjust the phase of the signal supplied thereto regardless of whether the magnitude of the phase shift applied by each transmission phase adjuster may be different, if required.

The phase-adjusted signal from the first transmission phase adjuster 760a is supplied to an input of the transmission combiner network 734 of the first combiner unit 730. Similarly, the phase-adjusted signal from the second transmission phase adjuster 762a is supplied to an input of the transmission combiner network 744 of the second combiner unit 740. Each transmission combiner network 734, 744 supplies the phase-shifted signals to the input of its associated duplexer 732, 742, which applies the signals, in transmission mode, to output ports 754, 752, respectively.

From the output ports, 752, 754, the phase-adjusted signals are supplied, through the feed lines 756, 758, respectively, to the input ports 712, 714 of the antenna assembly 702. In practice, the Feed lines 752, 754 can be made as long as desired, so that the TCU 704 can be located at a location distant from the antenna assembly 702, if required, several kilometers, for example.

From input ports 712, 714, phase adjusted signals are supplied by input carrier lines 720, 722, as Sa and Sb signals, respectively, to the first upper and lower subgroup splitter units 716A, 716B. From the first upper and lower subgroup divider units 716A, 716B, the signals Sa, Sb are divided and distributed to the antenna elements E1 to E12, through one or more of the second to the seventh subgroup divider units upper and lower 716C to 716H, and from where they are transmitted as an electromagnetic signal to the cell's mobile radios

The manner in which the signals Sa, Sb are divided and distributed to elements E1 through E12 of antenna assembly 702 will be readily appreciated by those skilled in the art from the manner in which the splitter units are interconnected and from the description preceding. The splitter unit arrangement provides a good approximation to a linear phase through the antenna when the antenna is electrically tilted at base station 1760. This is accomplished by using only two feed lines, 756, 758 to provide a relatively simple and cost-effective tilt system.

Figure 8 illustrates the apparatus when configured to transmit and / or receive signals that have only a single polarization (eg, positive polarization), although, in practice, negatively polarized signals will also be transmitted / received. For each polarization, two feed lines 756, 758 are provided to antenna assembly 702 and two respective carrier lines 720, 722. Thus, the maximum number of power lines required for a dual polarity antenna is four, making the apparatus relatively simple in design.

The phase difference of the signals Sa, Sb determines the angle of electrical tilt of the antenna assembly and it will therefore be appreciated that by adjusting the amount of delay applied to the signals by the first and second transmit phase adjusters 760a, 762b, you can The angle of electrical tilt of the antenna assembly 702 can be adjusted. Furthermore, the TCU may be at a remote location from the antenna assembly itself. The existence of the additional phase adjustment arrangements 150E1-150E12 of each of the signal paths to the elements E1a E12 provides a means for further adjusting the phase of the signals supplied to each element in the subgroups 700A-700C.

Additional phase adjustment arrangements 150E1-150E12 may take the form of a mechanical phase adjustment arrangement such as a wedge type dielectric arrangement. Such phase adjustment arrangements are well known in the art and include a base plate through which the transmission line T runs to the

ES 2 289 151 T3 antenna element, and a generally flat plate of dielectric material arranged between the base plate and the transmission line T. The plate of dielectric material, commonly referred to as a "wedge", is generally rectangular with a triangular segment or V-shaped, cut from a longitudinal edge of it. The wedge is movable with respect to the base plate and the transmission line T in a direction generally transverse to the transmission line T. Due to its shape, the linear movement of the wedge causes a greater or lesser amount of dielectric material to be interposed between the transmission line and the base plate, thereby causing the propagation speed and, consequently, the phase of any signal on the transmission line T, is displaced by a magnitude dependent on the linear position of the wedge. Such linear motion is usually effected by a linear actuator in the form of a servo or other motion transducer.

The amount of phase shift applied to the signal on the transmission line T is set by the position of the wedge below the transmission line T and the "wedge angle", the internal angle of the V shape cut at the crib.

The viewfinder gain decreases as the magnitude of the tilt angle is increased, so at maximum tilt, the viewfinder gain can be reduced by up to 1.5 dB. It is preferable to limit the side lobe level rise to -15 dB (or less) when the tilt angle is increased to a maximum value. Consequently, the vertical radiation pattern (VRP) widens and a reduction in the absolute gain of the viewfinder occurs. When the side lobe gain can be relaxed to -10 dB relative to the viewfinder gain, then tilt angles of ± 20 ° are possible and higher viewfinder gain can be obtained.

In the receive mode, the signals received by the antenna elements are carried, through the duplexers 732 and 742, to the demultiplexers 736 and 746, respectively. A portion of these signals is thereby conveyed to differential phase shifters 760b, 762b associated with each network operator equipment. The signals from the differential phase shifters are then vector summed in multiplexer unit 725b. The appropriate setting of the differential phase shifters, associated with each particular network operator, will give rise to signals received in the antenna viewer, at the angle of inclination desired for that operator, adding in phase in the multiplexer 725b.

It will be appreciated that the differential phase shift may alternatively be executed by means of a fixed phase shifter at the position of one of the phase adjusters, 760b or 762b, and a variable phase shifter at the position of the other of said phase adjusters. phase, providing a phase shift differential relative to the fixed. It will also be appreciated that, to overcome the losses associated with splitting the received signal, an amplifier could be inserted somewhere in the signal path before the associated divider 725a (725b), for example following the duplexer 732 (742). Alternatively or additionally, taking appropriate precautions to prevent its operation from being interrupted by the transmitted signal, the amplifier can be installed inside the antenna assembly at the end of the input carrier lines 720,722, with the advantage that the received signal is then amplified before being subjected to losses on lines 720, 722.

The variable electrical tilt associated with each operator, as performed on base station 1760, is individual to each operator, while the additional tilt performed by mechanical phasing arrangements 150E1-150E12 is common to all operators. In any event, the existence of the additional mechanical phasing arrangements 150E1-150E12 provides operators with a means for "fine tuning" the electrical tilt of the antenna system. The additional tilt can be accomplished by mechanical means, as described above (eg, by movement of a dielectric material). Alternatively, however, the additional tilt may be performed electrically, for example by using electrical phase shifters of the type described in 780a, 760b, 762a, 762b.

In the embodiment shown in FIG. 8, differential phase control unit 750 including transmit and receive differential phase control subunits 750a, 750b, is disposed external to an operator base station 1760. In an alternative embodiment (not illustrated), the differential base control unit 750 may be located within the base station itself, within transmit and receive demodulators. In this case, the base station 1760 is provided with an external input port to allow control of the differential phase control unit 750. When differential phase control unit 750 is disposed within base station 1760, two transmitter paths are required within the base station (from each of the first and second transmit phase adjusters 760a, 760b for a given signal polarity), each of which may be provided with its own power amplification means, thereby allowing the total carrier power to be doubled.

Since the feed lines 756, 758 between the output ports 752, 754 on the TCU 704 and the input ports 712, 714 on the antenna assembly may need to be of a length on the order of 100 meters, there is a possibility that changes in the length of the power lines may affect the phase of the transmitted signals. The phase adjustment of signals on a transmission line is usually effected by altering the apparent length of the transmission line by predetermined amounts. Thus, any variation in the length of the feed line, due for example to thermal expansion or contraction of the feed line, can affect the phase of signals on the line.

IS 2 289 151 T3

The tilt sensitivity of a tilt antenna assembly such as that described above is typically 17 degrees of phase difference per degree of electrical tilt. If the required resolution and stability of the electrical tilt angle is +/- 0.2 degrees of the set electrical tilt angle, then the required Differential Phase Displacement Resolution and Stability (DPSRS) is given by:

DPSRS = +/- 0.2 x 17 degrees = +/- 3.4 degrees (phase shift)

Since the wavelength at, for example, 2 GHz is 15 cm, a differential phase shift of +/- 3.4 degrees corresponds to an Allowable Electrical Length Variation (AELV) given by:

AELV = (3.4 / 360) x 15 cm = 1.4 mm

The thermal expansion of a typical power cable is 0.01mm / m / degree centigrade. Thus, if the maximum length of a power cable is 100 m, and the temperature increases from 20 to 85 degrees Celsius, the increase in cable length will be (85 - 20) x 100 x 0.01 mm (= 6 , 5 cm).

The maximum allowable temperature difference between a pair of power lines, corresponding to the maximum allowable difference in length of 1.4 mm, is given by:

Maximum temperature difference = (1.4 / 0.01) x 100 = 1.4 degrees Celsius

This high sensitivity value to electrical length and temperature difference between the power lines gives rise to a need to ensure that the phase difference of the signals Sa, Sb at the output ports 712, 714 of the antenna assembly is the same as same as output ports 754, 752 of TCU 704.

Figure 9 is a block diagram of a first form of apparatus that automatically compensates for power line phase difference due to such thermal expansion or contraction of power lines 756, 758. The automatic phase compensation apparatus, shown generically at 900, it comprises first and second mixing sets, represented by dashed lines 902, 904. The first mixer assembly 902 includes first and second directional T-taps or couplers 910, 912, which loosely couple the signals on feed lines 765, 758 at the mixers. Each coupler 910, 912 has one input and two outputs. The inlet of the first coupler 910 is connected to the outlet of the second combiner unit 740 (not shown in Figure 9). The first outlet of the first coupler 910 feeds a first inlet of a first mixer 916 and the inlet of a 90 degree phase shifter 918.

The input of the second coupler 912 is connected to the output of the first combiner unit 730 (not shown in Figure 9). The first outlet of the second coupler 912 feeds into a first inlet of a second mixer 922 and the second inlet of the first mixer 916. The outlet of the 90 degree phase shifter 918 is connected to the second inlet of the second mixer 922. The second output of the first coupler 910 is connected to a signal input of a first variable phase shift apparatus (hereinafter "first phase adjuster") 914 whose signal output is connected to the output port 752. The first The output of the second coupler 912 is connected to a signal input of a second variable phase shift apparatus (hereinafter "second phase adjuster") 920 whose signal output is connected to the output port 754. The output of each of the first and second mixers 916, 922 is connected to the input of a respective first and second low-pass filter 924, 926, with the output of each low-pass filter being connected to first and second inputs, respectively. , of a feedback controller 928.

The second mixer assembly 904 is substantially identical to the first mixer assembly 902 described above. Thus, the second mixer assembly 902 comprises first and second bridge directional couplers 940, 942, each having one input and two outputs. The input of the third coupler 940 is connected to the input port 712. The first output of the third coupler 940 is connected to the input of the first divider unit 716A, upper subgroup, as shown in Figure 8. The second output of the third coupler 940 feeds a first input of a third mixer 946 and the input of a second 90 degree phase shifter 948.

The inlet of the fourth coupler 942 is connected to the inlet port 714. The first outlet of the fourth coupler 942 is connected to the inlet of the first lower subgroup divider unit 716B, shown in Figure 8. The second outlet of the fourth coupler 942 feeds to a first inlet of a fourth mixer 952 and the second inlet of third mixer 946. The outlet of second 90 degree phase shifter 948 is connected to the second inlet of fourth mixer 952.

IS 2 289 151 T3

The output of each of the third and fourth mixers 946, 952 is connected to the input of a respective third and fourth low-pass filter 954, 956, with the output of each low-pass filter being connected, via feedback cables. first and second 960, 962, to third and fourth inputs respectively of feedback controller 928.

The output of the feedback controller 928 is connected, through respective amplifiers 930a, 930b to a control input of the first and second phase adjusters 914, 920. The control input of each phase adjuster 914, 920 is arranged to adjust the amount of phase shift applied to signals at the control input, depending on the applied signal.

It will be understood from the foregoing that the first mixer assembly 902, the first and second phase adjusters 914, 920, the control unit 928, and the amplifiers 930a, 930b are located within the TCU 704 and that the second mixer assembly 904 is located generally in antenna assembly 702. In other words, the first and second mixer assemblies 902, 904 are located at opposite ends of, and are connected together by, feed lines 756, 758. This is shown and described in more detail with reference to Figure 11.

The automatic phase compensation apparatus 900 is arranged to compensate for any variation in phase difference between the signals Sa, Sb at either end of the feed lines 756, 758. Such variation can be caused, for example, by thermal expansion or contraction. differential between power lines. The power line variation phase compensation technique executed by Figure 9 is common to all signals transmitted by the antenna assembly, and is therefore common to all antenna operators.

In operation, the signals Sa, Sb, emitted by the first and second combiner units 730, 740, as described with reference to FIG. 8, are applied to the inputs of the first and second couplers 910, 912, respectively. The first coupler 910 extracts a portion of the signal Sa and feeds it to the first input of the first mixer 916 and to the input of the 90 degree phase shifter 918. The 90 degree phase shifter adjusts the phase of the extracted portion of the Sa signal by 90 degrees and applies it to the second input of the second mixer 922.

The second coupler 912 extracts a portion of the Sb signal and feeds it to the first input of the second mixer 922 and also to the second input of the first mixer 916. Each mixer 916, 922 mixes the signals received at its inputs and outputs the mixed signal to the first and second low-pass filters 924, 926, respectively. It will be appreciated that the mixed signal supplied to the first low-pass filter 924 from the first mixer 916 will be proportional to the carrier component "in phase" of the signals Sa, Sb, while the signal supplied to the second low-pass filter 926 by the second mixer 922 will be proportional to the quadrature carrier component of the signals Sa, Sb. The use of the "in-phase" and quadrature components is necessary in order to obtain an unambiguous measurement of the phase difference between the Sa and Sb signals.

Low-pass filters 924, 926 remove essentially all but DC terms from the mixed signals, including carrier components and any transients that result from carriers having a null value following amplitude modulation in the signals. mixers, and apply the DC signals to the first and second inputs of feedback controller 928.

The signals Sa, Sb applied to the second mixer assembly 904 on the feed lines 756, 758, are also extracted by the third and fourth T-taps 940, 942 and applied to the third and fourth mixers 946, 952 in the same way as described above. The outputs of the third and fourth mixers are thus proportional to the carrier component in phase and the quadrature component of the signals Sa, Sb, respectively. The mixed signals are applied to the third and fourth low-pass filters 954, 956, which again filter all the terms, except the DC, of ​​the signals, and the DC signals are then applied to the third and fourth inputs of the signal. feedback controller 928.

An example of the outputs from the first and second (or third and fourth) low-pass filters is shown in Figure 10 as a function of the phase difference between the signals at the inputs.

By comparing the outputs of the low-pass filters 924, 926, 954, 956, the feedback controller 928 is able to calculate the following properties of the antenna system: the phase difference of the signals Sa, Sb in the TCU, the difference of phases of the signals Sa, Sb in the antenna assembly 702 and the phase error adjustment required to compensate for the differences in phase difference between the control unit and the antenna assembly.

In addition, the feedback controller 928 is capable of determining the carrier power of the signals Sa, Sb in the control unit 704, the carrier power of the signals Sa, Sb in the antenna assembly 702 and the loss or attenuation signal along the length of feed lines 756, 758.

The feedback controller 928 is then operable to output a control signal that is applied, through the amplifiers 930a, 930b, to the phase control inputs of the first and second phase adjusters 914, 920. The first and second phase adjusters adjust the amount of phase shift applied to the signals Sa, Sb in dependence on the control signal from the feedback controller 928 so that the error is reduced to a minimum level. In other words, the feedback controller 928 is operable to

ES 2 289 151 T3 ensure that the phase difference between the signals Sa, Sb in the control unit 704 is practically equal to the difference in phases between the signals Sa, Sb in the antenna assembly 702. The process is carried out on the Aggregate waveform of all carriers and phase compensation is performed when the phase difference in the antenna assembly has been separated from the phase difference in the control unit by a predetermined amount. Thus, any variation in the phase of the signals from the power lines 756, 758 is compensated.

A preferred form of block antenna system is shown in Figure 11, illustrating how the automatic phase compensation apparatus shown in Figure 9 can be incorporated into the system of Figure 8. Although the scale of the drawing is such that individual parts of the system are shown in less detail than in the preceding figures, and although connections are shown for only one user and only one polarity, it will be understood that the system allows up to five 1760A-1760E operators. use the antenna system essentially simultaneously, whereby each operator transmits and receives signals in a different operator frequency band.

Two TCUs 704a, 704b are shown in Figure 11, illustrating how the system of the present invention can be used with a dual polarity antenna assembly 702. Each TCU 704a, 704b includes an automatic phase compensation apparatus 900 similar to that shown in FIG. 9, part of which is located in the antenna assembly 702 itself, a pair of combiner units 730, 740 similar to those illustrated in FIG. 8, and five DPCUs 750 (only one complete DPCU shown), one for each operator, similar to those shown in Figure 8.

Each operator 1760A through 1760E has a transmitter port 726a and a receiver port 726b on base station 1760, each of which is connected to a respective DPCU in the manner described above. Since there are five operators who may wish to use the antenna system, the TCU includes ten differential phase control subunits, two for each operator. The outputs of the differential phase control subunits are connected to the inputs of the transmission combiner networks 734, 744 or to the outputs of the demultiplexers 736, 746 in the first and second combiner units 730, 740 in the manner described with reference to figure 8.

The output of each combiner unit 730, 740 is applied to the first and second mixer assemblies, respectively, of the automatic phase compensation apparatus 900, as described with reference to FIG. 9. Any variations in the phase difference between the signals Sa, Sb, as measured in TCU 704 by mixer assembly 902 and in antenna assembly 702 by mixer assembly 904, affect the angle of inclination of the antenna assembly for all operators and are thus compensated by the automatic phase compensation apparatus 900. The compensated signals are then applied to the antenna assembly for transmission in the conventional manner.

As mentioned above, each of the transmission combiner networks 734, 744 in the combiner units 730, 740 has five inputs and each of the demultiplexers 736, 746 has five outputs. It will be understood, therefore, that although two differential phase control subunits are required for each operator, one for transmitting and one for receiving, the five operators are capable of sharing the two combiner units 730, 740 in the TCU 704. Each of the other operators that the base station uses has a respective pair of differential phase control subunits, the outputs of which are connected to other inputs of the transmission combiner networks 734, 744 or outputs of the multiplexers 736, 746 of the combiner units 730, 740. Since the differential phase shift of signals occurs prior to multiplexing by transmission combiner networks 734, 744, an individual tilt angle can be set by each operator independently.

Although the apparatus of Figure 11 is advantageous in that it compensates for any differences in feed line lengths 756,758 due to, for example, differential thermal expansion or contraction between the lines, the phase compensation method is common for all system operators. In a further preferred embodiment, phase compensation is applied separately for each operator. Additionally, the apparatus of figure 11 only allows the compensation of differences originating from the length of the power lines to an antenna assembly, while, in practice, phase difference errors can originate in the combiner units. 730, 740 and on incoming carrier lines 720, 722, for example.

Figure 12 is a block diagram of an antenna system incorporating a second form of apparatus, which is arranged to compensate for any variations in the phase difference of the signals Sa, Sb between the end of the antenna element of the path of transmission and the base station end of the transmission path for each operator separately. In this embodiment, the antenna system comprises an antenna assembly 702 and a TCU 704 arranged as described with reference to Figure 8. Furthermore, the antenna assembly includes a vector measuring receiver module (VMRM: module) 1010. The VMRM 1010 comprises a Vector Measuring Receiver (VMR) 1012 and a Vector Measuring Receiver Controller (VMRC) 1014 connected thereto. In Figure 12, the antenna assembly 702 is also a dual polarity system and requires the existence of two VMRs as shown, each of which is connected to the common VMRC 1014. However, for clarity, they will only be described the connections and operation of the VMR 1012 for one polarity. As an alternative, a single VMR may be included, the switching means being arranged to switch the inputs to the VMR between the two polarizations of the system.

The TCU 704 includes a TCU Controller (TCUC) 1016 that is connected to the VMRC 1014 via a controller cable 1018 that is capable of carrying digital signals. Controller cable 1018 is also

ES 2 289 151 T3 arranged to carry the power required by the VMRM 1010 in the antenna assembly 702. The TCUC 1016 has a control output that is connected to the control input of each of the transmit and receive phase adjusters 760a, 760b, 762a, 762b in the two differential phase control subunits 750a, 750b. The TCUC 1016 also has a control input arranged to receive a second signal from a network operator to set the required tilt angle for the antenna assembly 702. Interposed on each of the input carrier lines 720, 722 is a respective one. T-tap or tracker 1020, 1022. The output of each tracker 1020, 1022 is connected to an input of the VMR 1012.

Figure 13 is a schematic block diagram of the VMR 1012 and illustrates its connection to the VMRC 1014. The output of each of the T-sockets 1020, 1022 is fed to the input of a respective attenuator 1024, 1026, whose output is connected to a first input of the respective first and second receivers 1028, 1030.

The output of the first receiver is fed to the input of a first limiter 1032, the output of which is connected to a first comparator 1034, through a 90 degree phase shifter 1036, and also directly to the input of a second comparator. 1038. The output of the second receiver 1030 is fed into a second limiter 1040, the output of which is directly connected to both the first and second comparators 1034, 1038.

Each of the first and second receivers 1028,1030 is tunable by means of a local oscillator 1042. The local oscillator 1042 generates a signal at a predetermined frequency that is combined at the respective receiver with the signal from the T-taps to produce an intermediate frequency output signal, the intermediate frequency signal being applied to the respective limiters 1032, 1040. The purpose of the local oscillator 1042 is to make it possible to tune the first and second receivers 1028, 1030 to each of the frequencies used by the operators. This makes it possible to measure the phase of signals Sa, Sb of more than one operator, and thereby differences in error compensation between different frequencies of operators can be explained.

The output of each of the first and second comparators 1034, 1038 is connected to the input of a respective low pass filter 1044, 1046, the outputs of each filter being fed to respective inputs of the VMRC 1014.

With reference to both Figures 12 and 13, in operation the TCU 704 operates in the manner described above to supply the signals Sa, Sb over the feed lines 756, 758, the signals of which are input to the antenna assembly 702 at the ports of input 712, 714 and applied to input carrier lines 720, 722. The first and second T-taps 1020, 1022 extract a portion of the respective signal Sa, Sb and apply the extracted portion to the respective attenuator 1024, 1026. The purpose of the attenuators is to fix the signal input to the respective receiver at the level that provides optimal performance of the receiver with respect to its dynamic range, linearity and noise immunity. The attenuated portion of the signal Sa, Sb is combined in the respective receiver 1028, 1030 with the signal applied thereto by the local oscillator 1042 and the intermediate frequency signal emitted by each receiver 1028, 1030 is passed through the respective limiter 1032, 1040 so that amplitude variations within the signals are eliminated.

The extracted portion of the signal Sa is fed to the first comparator 1034 through the phase shifter 1036 which adjusts the phase of the signal by 90 degrees. The extracted portion of the Sb signal is fed directly to the first comparator 1034. The output of the first comparator 1034 is applied to the first low-pass filter 1044 which removes essentially all terms, except DC, from the signal, including any residual carrier components of the comparator output and also any transient variations due to amplitude. of the signals at the input to the comparators passing through a null value.

The extracted portion of the signal Sa is also fed directly to the second comparator 1038 as its extracted portion of the signal Sb. The output of the second comparator 1038 is applied to the second low-pass filter 1046, which, like the first low-pass filter, essentially removes all but DC terms from the signal, including any residual carrier components from the output. of the comparator and also any transient variations due to the amplitude of the signals at the input to the comparators that pass through a null value.

The output of the first low-pass filter 1044 is thus the quadrature representation of the phase difference between the signals Sa, Sb while the output of the second low-pass filter 1046 is the "in-phase" representation of the phase difference between the signals. Sa, Sb signals. Both quadrature and in-phase representations are required in order to provide an unambiguous measurement of the phase difference between the Sa, Sb signals.

The first and second receivers 1028, 1030 also generate a respective Receiver Signal Strength Indication (RSSI), each of which is applied to the VMRC 1014 for transmission to the TCUC 1016. The RSSI is used to incorporate testing purposes and as an indicator for Health and Safety assessments. The VMRC 1014 is also provided with a 1048 heater and temperature sensor. The sensor measures the temperature in the VRMC and is operable to drive the heater in order to limit the minimum operating temperature to a satisfactory value to ensure proper operation.

The output of the VMRC 1014 is a direct measure of the phase difference between the signals Sa, Sb and this is applied to the TCUC 1016 through the digital control cable 1018. The TCUC 1016 is arranged to tune the first and second receivers 1028, 1030 at a particular frequency and to obtain the required tilt angle (i.e.

ES 2 289 151 T3 the required phase difference between the signals Sa, Sb) at that frequency. On reception of the measured phase difference between the signals Sa, Sb, at the required frequency, the TCUC 1016 is operable to apply control signals to the control inputs of the first and second transmit and receive phase shifters at each one of the differential phase control subunits 750a, 750b such that the actual electrical tilt angle of the antenna assembly 702 is essentially the same as the required electrical tilt angle.

It will be appreciated that the apparatus of Figure 12 makes it possible to independently compensate for phase shift errors between different operators (ie, due to their different operating frequencies), thanks to the VMRM 1010. The measurement and phase adjustment process can be carried out when the system is initially switched on, when the angle of electrical inclination is required to be changed and / or periodically to compensate for thermal fluctuations in the power lines, for example every 10 minutes.

In addition, the TCUC 1016 can be set in either a local mode or a remote mode. In local mode, the electrical tilt angle required by each operator is set locally on the TCU 704. In remote mode, the required electrical tilt angle can be set remotely, either via radio link or over a line. telephone or similar.

The TCU 704 also displays, locally and / or remotely, the electrical tilt angles required by each operator, the actual electrical tilt angles of the antenna assembly, the error between the required and actual electrical tilt angles for each operator, the levels of RF power in the antenna assembly for each operator's signals, the temperature in the antenna assembly, and the TCU power supply voltages and currents.

Figure 14 shows the use of the antenna system of Figure 12 with a dual polarity antenna assembly by five operators. For clarity, only the connections for one polarity and one operator are shown. It will be clear that the embodiment of Figure 14 is similar to that of Figure 11, except that the automatic phase compensation apparatus of Figure 11 has been replaced by the VMRM 1010 of Figures 12 and 13.

In some circumstances, the apparatus of Figures 12 to 14 will be suitable for compensating for phase differences between different operators. However, the method is based on measurements determined through the transmission path, while the accuracy can be further improved by independently measuring phase differences through the reception path as well. For the purposes of this specification, the "transmission path" for signals is intended to mean the path followed by the delayed signals emitted by the combiner unit 704 as they are passed along the feed lines 756, 758, along the input carrier lines 720, 722 and to the antenna elements, and which includes the divider, the amplifier, the filter and other components present in this path. The "reception path" for signals is intended to mean the path followed by the signal received at the antenna elements when they are passed along the carrier lines 720, 722, the feed lines 756, 758 and to the combiner unit 704, and that includes the divider, the amplifier, the filter and other components present in this path.

Figures 15 and 16 show a further improved apparatus in which phase difference compensation is performed for both the transmission and reception mode separately (i.e., for transmission and reception paths separately), as well as for operator frequencies. individual. For simplicity, Figure 15 shows precisely two antenna subgroups (as opposed to the three subgroups in Figure 8), of a dual polarity antenna assembly 1502; a first subgroup 1500A 'with positive polarity and a second subgroup 1500B + with positive polarity and two subgroups also 1500A^-, 1500B negative polarity. The operation is the same for the bias channel and therefore will not be described in more detail. When only two subgroups 1500A + and 1500B + are provided, the splitter (716A-716H) and combiner (726A, 726B) arrangement of the apparatus of Figure 8 is not required, and the carrier lines 720, 722 supply input signals directly to the devices. subgroups 1500A, 1500B.

The method used to measure and correct variations in the delay time between the transmission and reception paths to control the angle of electrical tilt of the antenna measures the phase difference between the signal paths in both the transmission mode and the signal path. of reception. This is done using either the frequencies used for the base station transmitter (the downlink) or those used for the base station receiver (the uplink). Using this method it is possible to measure the phase difference between pairs of power lines at the frequencies used for each allocation of operator transmission and reception frequencies.

Considering first the differential phase measurement for the reception path, the antenna assembly (shown in Figure 15) includes a Calibration Tone Generator (CTG) 1610 comprising a calibration oscillator 1612, a variable attenuator 1614, or band pass filter 1616 and a second attenuator 1618. The 1012 Vector Measurement Receiver in Figures 8 and 12 is also identified, along with a 1640 Antenna Calibration Controller (ACC) that controls the 1610 Calibration Tone Generator (CTG) and communicates with the Controller. System Calibration Controller (SCC) on the 1760 base station. The CTG 1610 is arranged to generate unmodulated tones in a 200 Hz bandwidth that are preferably stabilized at +/- 10 kHz in 2 GHz or +/- 2 parts in 10⁵. The tone is set to the frequency required to measure a particular reception slope of the operator by means of the Antenna Calibration Controller (ACC) 1640. The signal level can be adjusted by means of the attenuator 1614 and the filter of

ES 2 289 151 T3 bandpass 1616 is arranged to prevent signals at transmit frequencies from entering the calibration oscillator 1612 (i.e., only receive frequencies can pass) and the second attenuator 1618 is required for matching purposes impedance.

The tone signal is applied to the first splitter / combiner unit 1620 (SP1) by which it is divided along four equal paths 1660a, 1660b, 1662a, 1662b, two equal paths 1660a, 1660b, for first and second 720, 722 biased and two signal paths 1662a, 1662b for first and second feed lines 1521, 1523 biased. Each signal is injected through respective splitter / combiner units 1622-1628 (SC1-SC4) to the respective power line. For simplicity, only power lines 756, 758 and carrier lines 720, 722 will be considered for the subgroups for the positive polarity group, but it will be appreciated that the same phase compensation principles apply to power lines 1756, 1758 and the carrier lines 1720, 1722 for the negative polarity group.

The tone signal, or each of them, is injected onto carrier lines 720, 722 at the edge of each receive channel (typically 5 MHz separate channels) through a 1630 directional coupler, such that the signal tone does not interfere or add to the received signal. The tone signal supplied by each of the carrier lines 720, 722 is supplied to a respective arrangement 1642, 1644 of band pass filters and amplifiers. Arrangements 1642, 1644 are identical and each includes a respective receive frequency arm 1642a, 1644a and a respective transmit frequency arm 1642b, 1644b. The receive frequency arm of each arrangement includes a band pass filter (BPF, FRx) to selectively transmit receive frequencies. The transmit frequency arm of each arrangement includes a band pass filter (BPF, FTx) to selectively transmit transmit frequencies. It is also desirable to include a low noise amplifier (LNA) in the receiving frequency arm 1642a, 1644a.

Referring to FIG. 16, the tone signals transmitted through transmission frequency arms 1642b, 1644b are supplied to base station 1762 at ports 752, 754 (also shown in FIG. 12). Figure 16 shows base station 1762 for five different operators, although base station components are shown for only some of the operators. When the notation in Figure 16 indicates "/ 5", this indicates that five such components are present (although not shown), and similarly for other numbers (eg "/ 30" indicates that there are 30 such components).

For the first subgroup 1500A 'of antenna 1502, and the respective carrier line 720, a single filter arrangement 1650a is provided at base station 1762 for the receive signals, which are then divided by a splitter unit 1651 of five modes for supplying a respective variable delay unit 760b (ie, equivalent to that shown in FIG. 12 and only one of which is shown for one of the operators). The receive signals for the other subgroup 1500B, and the respective carrier line 722, pass through a filter arrangement 1650b to a second variable delay unit 762b (likewise only one of which is shown for one of the operators) .

Receive signals transmitted back on carrier lines 720, 722 to base station 1762 are supplied through respective filter arrangement 1650a, 1650b to a second Vector Measurement Receiver (VMR) in the control unit of antenna or base station 1762 through respective directional couplers 1632, 1634. When in the receive mode, the tone signals originating from the CTG 1612 and supplied by the carrier lines 720, 722 follow the same reception path as the reception signals. The Vector Measurement Receiver 1638 is under the control of the System Calibration Controller 1646 and is operable to select the appropriate pair of directional couplers 1632, 1634 for a selected operator, whereby a sample of the received tone signal is obtained. for measurement. Measurements for the delay between the tone signals transmitted through lines 720, 756 and through lines 722, 758 (ie, a "receive path phase difference measurement") are obtained by the VMR 1638, along with signal strength information, and returned to SCC 1446. The difference measured in phase difference between the carrier pairs 720, 756 and 722 and 758 at the antenna and combining unit end of the reception path, is used to adjust the phase difference in the antenna by an amount necessary to ensure that the electrical tilt angle required by an individual operator is what is achieved. Specifically, the SCC 1646 adjusts the variable delay associated with the selected operator to achieve the required delay, allowing for any discrepancies in the receive path. This operation can be carried out for each operator in shifts, as often as necessary to maintain the correct adjustment of the antenna.

For receive path calibration (i.e. phase compensation) it is desirable that the selected tone signal have a frequency at or near the edge of the carrier frequency channel, but equally the frequency of the tone signal. can be selected to fall within the operator's frequency channel. Typically, the receive path channels have a 5 MHz bandwidth, and the tone signal preferably has a 200 Hz bandwidth.

Considering the transmission path below, with reference to FIG. 16, antenna base station 1682 also includes respective transmission filter arrangements 1652A, 1654A associated with feed lines 720,722. The transmit filter arrangements 1652A, 1654A are arranged to filter transmit frequency signals for operator A, but prevent the receive frequency signals from passing through. To

ES 2 289 151 T3 each of the operators B and E, corresponding transmission filter arrangements 1652B, 1652E and 1654B, 1654E are also provided for each of the carrier lines 720, 722.

In this particular embodiment of the invention, operators C and D transmit through the negative polarization antenna elements (1500A^- and 1500B), while operators A, B and E transmit through the positive polarization elements (1500A +, 1500B +).

As described above for Figures 8 and 12, the transmission signals for each of the three operators A, B and E are divided by the divider unit 725a and supplied through the respective variable delay unit 760a (A , B or E) to filter arrangements 1652A, 1652B, 1652E, 1654A, 1654B, 1654E. Each filter arrangement is configured to pass signals within a particular operator frequency band, and transmits the selected operator's transmission signals to carrier lines 720, 722, respectively.

For transmission path calibration purposes, the directional coupler 1630 on antenna 1502 (as shown in Figure 15) extracts a small portion of the transmission frequency signals from the carrier line 720, 722 and supplies two signals over the lines 1656, 1658 to Vector Measurement Receiver (VMR) 1012 on antenna 1502. For each carrier frequency channel, the VMR 1012 measures the phase difference between transmission signals supplied by power line 720 and those supplied by power line 722 at essentially the center frequency of the transmission signal bandwidth. selected, referred to as the "transmission path phase difference measurement". The transmission path phase difference measurement bandwidth is preferably selected to be essentially the same as the bandwidth of the transmission signal for each particular operator.

The calculated transmission path phase difference measurement at the antenna is fed back to ACC 1640, which communicates with SCC 1646 (as shown in Figure 16) at base station 1762. The measured phase difference between transmit signals at the antenna is compared to the measured phase difference as set at base station 1762 by SCC 1646 and an adjustment is made to the antenna phase difference to ensure that the required electrical tilt angle is achieved for each operator in transmission mode, despite any difference in phase difference between the ends of the transmission paths.

The phase difference compensation method described with reference to Figures 15 and 16 is advantageous in that it makes it possible to accurately determine the angle of inclination by justifying differences d phases, both in transmission mode and in reception mode independently, to each of the operators A to E independently. The methods allow all transmit and receive operators to calibrate for differential phase between the transmit and receive paths, not only during continuous operation but also for manufacturing and testing alignment, inspection, and maintenance. The calibration or compensation operation can be performed for each operator in shifts as frequently as necessary to maintain the correct antenna adjustment.

In the arrangement of Figure 9, for example, the required angle of inclination is only achieved precisely at one frequency, as for other frequencies the phase difference across the supply lines 756, 758 will be different and therefore the direction in the one where the phases add up to give maximum gain (the "viewer") will be different. In such systems, the base difference is not only different for different transmission frequencies (that is, for different operators), but it is different across the transmission and reception paths for each. Using the system of figures 15 and 16, the desired electrical tilt angle can be achieved exactly for each operator and it can be ensured that it is the same for both transmission and reception modes, if required, since any effect is compensated. phase redifference that would otherwise occur between the two trajectories. Also, if an operator requires the tilt angle to be different in transmit mode from tilt angle in receive mode, the system can provide it.

As an alternative to using a tone signal to calibrate the receive path, a spread spectrum signal can be generated in generator 1612. It will be appreciated that using this technique, directional couplers 1632, 1634 couple the spread spectrum calibration signal. RF signal with received signals for measurement on the VMR 1638 at base station 1762.

In order to avoid providing an oscillator 1612 on antenna 1502 on top of the antenna mast, along with the attenuation and filter components, 1614, 1616, 1618, a frequency converter may be provided to allow a sample of the transmission frequency signals (for each operator) is moved to the corresponding reception path. By measuring the delay between the transmit signals at the bottom of the receive path, the differential delay around the entire transmit / receive path can be determined and the appropriate adjustment can be made for each carrier frequency channel in the SCC. 1646. In order to obtain a separate measurement for the transmission path only, the same transmission signal can be transferred to the reception path for each operator channel, that is, the transmission signal for one operator is used essentially as a transmission signal. calibration for all operators. By comparing the differential phase measurement for the receive path with the differential phase measurement for the transmit / receive loop, the phase difference for the transmit path can be determined for each operator.

IS 2 289 151 T3

As a further alternative embodiment, only one Vector Measurement Receiver 1012 needs to be provided, and this is in base station 1762. In this case, the 1502 antenna's Calibration Generator Oscillator (CGO) operates at both the transmit and receive frequencies, so that the transmit frequencies are passed back through the carrier lines. 720, 722 for the phase difference to be measured at base station 1762. The VMR 1012 on base station 1762 therefore has to tune to transmit frequencies as well as receive frequencies. Transmission frequency signals can be sent back over carrier lines 720, 722 to VMR 1012 at base station 1762 for base offset purposes when the transmission path does not include amplifier or other active devices that prevent reverse pass-through. .

It will be appreciated that the present invention provides an effective way of allowing multiple operators to use a cluster antenna assembly in phase where the electrical tilt angle of the antenna assembly may be different for each operator and can be remotely and independently adjusted by the operator. operator. The electrical tilt angle for each operator can also be different in the transmit and receive modes, or be made precisely the same.

When the means for controlling the angle of electrical inclination of the antenna assembly is located at a sufficient distance from the antenna assembly for differential thermal expansion or contraction of the power lines, and therefore variations in the phase of the signals in the power lines. feeding, being a problem, The invention provides an effective method and apparatus for compensating for such phase variations so that the angle of electrical tilt in the shaft is the same angle of electrical tilt required by each operator.