Multiband directional antenna having a switchable beam direction

(42) Date of commencement of the patent: 15. 7.1990 (45) Date of issue: 11. 2.1991

<td>(56) Documents:</td><td>(73) Patent owner:</td>

<td>DE-AS1239745 DE-AS1059980 US-PS 2619596</td><td>WEIGL JÜRGEN A.</td>

<td>HAM RADIO MAGAZINE (GREENVILLE, NH), MAY 1988,</td><td>A-8053 GRAZ, STYRIA (AT).</td>

<td>PP 74-78 '' A SHORTEND 40-METER FOUR ELEMENT</td><td></td>

<td>SLOPING DIPOLE ARRAY "</td><td>(72) Inventor:</td>

<td>THE ARRL ANTENNA BOOK, 13TH ED., (NEWINGTON, CT),</td><td></td>

<td>CHAPTER 8, PP 200,201</td><td>WEIGL JÜRGEN ANTON</td>

<td></td><td>GRAZ, STYRIA (AT).</td>

(54) MULTI-BELT ANTENNA WITH SWITCHING DIRECTION

CQ

AT 392 173 (57) The present invention proposes to construct switchable directional antennas with a plurality of elements (1) for two or more frequency ranges, in which the connecting line (2) to a central direction switch (3) causes a detuning of the element resonance in the case of non-supplied elements results so that it can not work excited elements as a radiation-coupled parasitic on several frequency ranges. To achieve this, a reactance (5) is introduced into the connecting line (2) element directional switch such that the connection line (2) in connection with this reactance (5) in the feed point not directly fed elements results in the necessary for the parasitic operation dummy load , For this purpose, the transformation of the introduced reactance (5) via the connecting line (2) Element direction switch must give the necessary reactive load at all operating frequencies. This can be done either by a reactance at the open end directly at the direction switch or by inserting the reactance along the line, in a relation to the operating wavelength to be considered distance from the direction switch (3).

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AT 392 173 B

The invention relates to switchable directional antennas for at least two different frequency ranges equally effective, consisting of two or more, by means of methods known per se for operation on several frequency ranges suitable elements, each with a connecting line to a direction switch, of which at least one element operates as a direct-fed radiator, while at the same time remaining elements are used as radiation-coupled parasitic radiators, wherein individual elements can be converted by the directional switch from a powered element into a parasitic element, and wherein the connection line antenna direction switch contributes to the appropriate detuning of non-powered elements for parasitic operation

In such antennas, at least one antenna element, referred to below as an element, is fed directly by the direction switch. At the non-powered antenna terminals of the remaining elements is now, parallel to the antenna input, the connection line antenna direction switch. This line piece now works as the resonance frequency affecting stub. By suitable choice of the length of the connecting line thus non-powered elements can be operated as a radiation-coupled parasitic heater. This results in a Richtwiikung the overall antenna, which is determined by selection of the elements fed while doing successful conversion of unserviceable elements in radiation-coupled parasitic elements, the necessary shift of the resonant frequency of these elements through the connecting line, the beam direction is determined by the direction switch.

Such antennas are preferably inexpensive to build for low frequencies where mechanically rotatable antennas are hardly possible anymore. In addition there is the advantage of a rapid change of direction compared to mechanically rotatable directional antennas. Such antennas can z. B. from a single mast and are known for example from Ham radio magazines, May 1988, pp 74 - 78, A short-end 40-meter four element sloping dipole array known.

However, such antennas have so far lacked the possibility of using them on several independent frequency ranges as directional antennas in the manner described. Although the individual elements can be determined by known methods, for example by using suitable blocking circuits, or, for example, according to DE-AS 1059980 by construction of several different length dipole beam, which are connected via frequency-dependent coupling elements with a common pair of terminals, wherein the associated radiation origins coincide at least approximately or also by using suitable crossovers, for example according to DE-AS 1 239 745, to interpret, that they are in resonance at several independent frequencies or a wide frequency band and can be operated as a directly fed element, the operation of the non-powered elements as radiation-coupled parasitic radiators by means of conversion of the connecting element element-directional switch into a, However, the element resonance suitable detuning stub is so far only possible for one operating frequency.

The multi-band antenna described in US Pat. No. 2,619,596, which allows operation on a plurality of independent frequencies, wherein the connection line of the antenna elements substantially contributes to achieving the desired radiation pattern, also achieves only the radiation pattern of a simple dipole in its original design and thus no - by parasitic elements achievable pre / reversion. By adding parasitic elements, as noted in U.S. Patent No. 2,619,596, although directivity can be achieved, a separate parasitic element must be added for each frequency range used. In addition, such an antenna is in turn only mechanically rotatable.

Based on this prior art, the present invention seeks to enable the operation of such directional antennas on multiple frequency ranges (multi-band directional antenna), without having to take a much higher circuit complexity in purchasing.

This object is achieved by multiband directional antennas, in which the connecting line antennas direction switch not directly fed elements in conjunction with a built-up of one or more switching elements reactance, for example, a parallel inductance or capacitance, the necessary detuning of these antenna elements results in parasitic operation on several frequency ranges.

With the invention it is proposed, by inserting a suitably selected reactance into the connecting line, to build it up to a stub line which detunes the antenna elements in a suitable manner for parasitic operation. In the simplest case, this reactance can consist of an inductance or capacitance which is inserted at one point between the two conductors of the connecting line. This results in the possibility of achieving the necessary detuning of the radiation-coupled elements for parasitic operation on at least two independent frequency ranges. Hiebei gives the transformation of the reactance (X) along the line with the length (I) and the characteristic impedance (Zw) at these frequency ranges the necessary reactive load in the feeding point for parasitic operation of the radiation-coupled elements.

Usually, the reactance will be inserted directly at the direction switch. Another way to achieve multi-band operation for directional antennas described is characterized in that the reactance is inserted in a, to be considered in relation to the operating wavelength Enfemung (11) from the directional switch in the connecting line. To determine the values ​​for the length of the connecting line and the necessary reactance is advantageously carried out so that the necessary inductance or Capacity for

-2AT392173B

Achieving the necessary in the antenna feed point for parasitic operation reactive load as a function of the length of the connecting line for both operating frequencies (fl) and (f2) is determined. The intersections of the curves described thereby provide the solution possibilities for multi-band operation. In the case of switching elements inserted directly at the direction switch, values ​​which are difficult to implement can occur both for the length (1) of the connecting line and for the reactance. In this case, the insertion of the reactance at a distance (11) from the directional switch to be considered in relation to the operating wavelength can provide a viable solution.

A possible embodiment of the antenna elements for multi-band operation is characterized in that the individual elements in a conventional manner consist of multi-band antennas with resonant circuits or extension coils.

These are frequency-dependent insulators, which form high resistances at their resonance frequency and thus shut off the subsequent antenna parts (so-called. Traps). This makes it possible to form dipole elements that resonate at multiple frequencies. Thus, compared to other multirange antennas, multiple frequency ranges can be used with a single dipole. At the same time it comes for the lower operating frequencies, in which the inductive component of the blocking circuits comes into play, to an advantageous shortening of the element length.

If elements are required for particularly large wavelengths, it is often expedient to construct strongly shortened elements with extension coils. The closer this coil is moved to the current amplitude of the antenna, the greater is its shortening effect. It can now be a point on the antenna conductor to find a coil there just affects so that the radiator is resonant at two frequencies For this, the ratio of the two frequencies must be sufficiently high, so that the higher enough frequency, the extension coil enough represents high reactance and thus, similar to a blocking circuit shuts off the outer antenna elements for this frequency. At the lower frequency, on the other hand, the extension coil resonates the entire antenna.

Often directional antennas with certain polarization are necessary. In such cases, directional antennas described in which the elements emanate in a manner known per se from a point common to all or at least several elements prove to be particularly advantageous.

For example, antennas with vertical polarization are often required in the mid- and short-wave range, since low beam angles with vertical beams can often be achieved more easily and less expensively than with horizontal beams. Low radiation angles often require very high installation heights and thus result in severe mechanical problems. A particularly advantageous structure for the directional antenna described is therefore given, for example, if the individual elements emanate from a common point. This can be achieved, for example, by means of a central mast from which the individual elements, which for example consist of multiband glands with resonant circuits, are realized. Although the dipoles in such an arrangement no longer run exactly vertically, the radiation is largely vertically polarized and thus allows, as stated above, relatively low radiation angles at long operating wavelengths. For similar reasons, a similar structure may be required for other frequency ranges and other required polarization.

To explain the invention, embodiments are described below with reference to the drawing:

1 shows a two-element directional antenna with parallel elements and reactance at the open end of the connecting line.

Fig. 2 shows the embodiment of a connecting line wherein the reactance is inserted in a, to be considered in relation to the operating wavelength distance (II) from the directional switch in the connecting line.

Fig. 3 shows a three-element directional antenna with common anchoring point.

Fig. 4 shows as detail (2) to Fig. 3: Design of the connecting line element-directional switch.

Fig. 5 shows as detail (3) to Fig. 3, embodiment for a direction switch.

FIG. 1 Is shown as a first embodiment, an antenna consisting of two dipole-shaped elements (1) via the connecting line (2) with the length (1) either via the direction switch (3) to the adapter (4) to the line (6) to the transmitter / Receiver can be relayed. At the end of the connecting line is at the contact terminals of the direction switch (3), the reactance (5). In the case of the unused antenna, the reactance (5) transformed along this line via the line (2) is now parallel to the input impedance of the antenna in the feed point of the antenna. This results in a reactive load at both operating frequencies, which detunes the unused element so that it works as a radiation-coupled parasitic radiator.

In order to determine the values ​​for the length of the line (2) and the reactance (5), the procedure is advantageously such that the necessary inductance or capacitance for achieving the reactive load required in the feed point of the antenna for parasitic operation is dependent on the length (1) of the Connection line for both frequencies (fl) and (f2) is determined. The intersections of the curves described thereby provide the solution for multi-band operation.

By inserting further reactances into the connection line, moreover, operation on more than two frequency ranges can be achieved.

-3AT 392 173 B

Fig. 2 shows another way to obtain the necessary reactive load on several frequency ranges. Not directly supplied elements are analogous to Fig. 1 at the direction switch on open terminals (idle). In the connecting line (2) is inserted in a, in relation to the operating wavelength to be considered for the distance (11) from the direction switch, a reactance (5) parallel to the line.

In the simplest case, the transformation of the open circuit at the direction switch over the length (II) at the operating frequency (fl) at the connection point of the reactance (5) represents a short circuit. The subsequent length (12) (reactance feed point) is thus predetermined by the transformation of this short circuit into the necessary reactive load in the feed point of the parasitic radiator. The reactance (5) is determined as follows: the idling at the direction switch transforms at the frequency (f2) over the line length (11) to a reactance (X '), which is now parallel to the reactance (5). Since this parallel connection via the transformation along the line length (12) at the frequency (f2) must give the necessary value of the reactive load for parasitic operation, thus the reactance (5) can be determined unambiguously. If the reactance (5) is realized by an interconnection of a capacitance and an inductance, it is possible to achieve the necessary reactive load for parasitic operation at three frequency ranges (fl), (f2) and (f3). For this purpose, the necessary reactance (5) is determined at the third frequency (f3) analogously to (fl). Capacitance and inductance can be calculated from the two values ​​obtained for the reactance.

In order to achieve realizable values, it may be favorable to extend the individual line lengths defined by the frequency (fl) by half wavelengths (relative to the frequency (fl)), since this does not change the transformation ratios for the frequency (fl). means.

However, the arrangement is not limited to the fact that the line piece (11) (terminals direction switch reactance (5)) provides a short circuit at one of the operating frequencies, but the line piece (11) may also have an operating-wavelength-dependent reactive component, the reactance (5) parallel, deliver. Likewise, the terminals of non-directly supplied elements at the directional switch could be short-circuited by this switch by suitable design. In this case, the above described ratios of idling at the direction switch would be replaced by a short circuit accordingly.

A particularly advantageous construction is shown schematically in FIG. Here, for example, three multiband dipoles (1) with resonance circuits (7) are braced by a common mast (8). The connecting lines (2) represent the connection element (1) - direction switch (3), wherein a matching member (4) allows the connection of the powered element to the transmitter / receiver leading line (6).

Fig. 4 illustrates a possible solution to achieve the necessary reactive load in the feeding point of the antenna; if the element is not fed via the direction switch (3) itself, there is an open circuit at the terminals and the non-powered elements work, as already stated for FIG. 1, as parasitic radiators. Likewise, however, an embodiment of the connecting line according to Fig. 2 would be possible.

Fig. 5 finally shows a possible embodiment of the direction switch (3), wherein the individual elements to the terminal pairs (Al), (A2), (A3) are connected. The control of the beam direction thus takes place by selecting the fed element via the two relays (Kl) and (K2).

Of course, it is in the above embodiments only exemplary configurations that are optimal values ​​for the particular application by calculation and attempt to determine. In particular, the design of the directional switch opens up several possibilities. Thus, for example, the directional switch may be constructed so as to connect, on the one hand, the directly fed element to the line (6) to the transmitter / receiver, while simultaneously shorting off the connecting lines (2) of non-directly fed elements at the terminals of the directional switch, such as this above as an embodiment of FIG. 2 has been described.

As well as the design of the directional antenna for two frequency ranges, as also shown in FIG. 2, by adding further reactances or dimensioning of the corresponding line lengths, detuning of unswept elements can also take place in more than two frequency ranges.

The invention is not limited to a certain number of individual elements, as well as the directional antennas described can be constructed as groups.