Isotropic antenna

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The invention relates to a unipolar antenna with a resonant quarter-wavelength extending vertically above a ground plane including a pair of input terminals disposed between the ground plane and the lower end of the emitter bar, the short-circuit transmission line being connected to the input terminals. 4 1

Unipolar antennas are widely used in telecommunication technology, especially in the frequency range between 20 and 200 MHz. Unipolar antennas include vertical quarter-wavelength emitters arranged for hemispherical radiations above the actual or virtual ground plane. The gain of such antennas is zero decibels, typically fed at its reference point and adapted to the coaxial line.

The radiator rod of the classic unipolar antenna is separated from the ground, and this separation also ensures uniform insulation. In such designs, the emitter bar tends to become electrostatically sensitive, and the protection against the danger of leakage towards the electronic device connected to the antenna is not sufficiently secure. The straight-line grounding of the emitter bar is comfortably achieved using a stacked unipolar as a radiator, which in addition to grounding the antenna impedances the reference circuit. The folded unipol, a-liv, provides dc earthing, can not provide safe protection against damage caused by overflows, since the length of the antenna is more than 10 times greater than the distance between two parallel rods and thus can occur at the base of the antenna. During the overflow, the flow, flowing into two parallel parts of the rod, can be extremely high and accompanied by a dynamic effect, 2 which can deform and damage the antenna. 229 849 MG Brown first suggested that the antenna should be connected to the ground via the short circuit. In this design, the electrical length of the shortened portion of the line is equal to a quarter of the wavelength and it extends vertically below the emitter bar. The presence of the lead portion has a mild effect on the antenna reference point impedance, which increases the bandwidth only slightly. The bandwidth of the unipolar antennas is predominantly designed by counterweight rods, by means of which the ground plane is imitated, and by the slenderness of the emitter bar. Bandwidth can be increased by increasing the diameter of the emitter bar, but the corresponding function is a logarithmic amalgam increase in bandwidth requiring a substantial increase in diameter. The re-latency bandwidth of commonly used unipolar antennas is approximately between 1 and yfc. that the antenna should be connected to the ground via the short circuit of the line. In this design, the electrical length of the shortened portion of the line is equal to a quarter of the wavelength and it extends vertically below the emitter bar. The presence of the lead portion has a mild effect on the antenna reference point impedance, which increases the bandwidth only slightly. The bandwidth of the unipolar antennas is predominantly designed by counterweight rods, by means of which the ground plane is imitated, and by the slenderness of the emitter bar. Bandwidth can be increased by increasing the diameter of the emitter bar, but the corresponding function is a logarithmic amalgam increase in bandwidth requiring a substantial increase in diameter. The re-latency bandwidth of commonly used unipolar antennas is approximately between 1 and yfc. that the antenna should be connected to the ground via the short circuit of the line. In this design, the electrical length of the shortened portion of the line is equal to a quarter of the wavelength and it extends vertically below the emitter bar. The presence of the lead portion has a mild effect on the antenna reference point impedance, which increases the bandwidth only slightly. The bandwidth of the unipolar antennas is predominantly designed by counterweight rods, by means of which the ground plane is imitated, and by the slenderness of the emitter bar. Bandwidth can be increased by increasing the diameter of the emitter bar, but the corresponding function is a logarithmic amalgam increase in bandwidth requiring a substantial increase in diameter. The re-latency bandwidth of commonly used unipolar antennas is approximately between 1 and yfc. In this design, the electrical length of the shortened portion of the line is equal to a quarter of the wavelength and it extends vertically below the emitter bar. The presence of the lead portion has a mild effect on the antenna reference point impedance, which increases the bandwidth only slightly. The bandwidth of the unipolar antennas is predominantly designed by counterweight rods, by means of which the ground plane is imitated, and by the slenderness of the emitter bar. Bandwidth can be increased by increasing the diameter of the emitter bar, but the corresponding function is a logarithmic amalgam increase in bandwidth requiring a substantial increase in diameter. The re-latency bandwidth of commonly used unipolar antennas is approximately between 1 and yfc. In this design, the electrical length of the shortened portion of the line is equal to a quarter of the wavelength and it extends vertically below the emitter bar. The presence of the lead portion has a mild effect on the antenna reference point impedance, which increases the bandwidth only slightly. The bandwidth of the unipolar antennas is predominantly designed by counterweight rods, by means of which the ground plane is imitated, and by the slenderness of the emitter bar. Bandwidth can be increased by increasing the diameter of the emitter bar, but the corresponding function is a logarithmic amalgam increase in bandwidth requiring a substantial increase in diameter. The re-latency bandwidth of commonly used unipolar antennas is approximately between 1 and yfc. by means of which the ground plane is imitated, and by the slenderness of the emitter bar. Bandwidth can be increased by increasing the diameter of the emitter bar, but the corresponding function is a logarithmic amalgam increase in bandwidth requiring a substantial increase in diameter. The re-latency bandwidth of commonly used unipolar antennas is approximately between 1 and yfc. by means of which the ground plane is imitated, and by the slenderness of the emitter bar. Bandwidth can be increased by increasing the diameter of the emitter bar, but the corresponding function is a logarithmic amalgam increase in bandwidth requiring a substantial increase in diameter. The re-latency bandwidth of commonly used unipolar antennas is approximately between 1 and yfc.

When considering a mechanical design, it should be picked up, the radiator coil is generally not insulated. To reduce ground capacitance relative to the ground, insulators that are exposed to excessive bending moment are used. The resistance of the insulator material to the bending moment is rather limited, the materials are rigid and rigid, which explains why the design of a suitable carrier is a critical factor in the whole work of the designer. The increase in the required bandwidth of telecommunication connections requires the use of antennas with a high relative bandwidth of 5 to 10 μm, which implies that despite all the advantageous properties of the unipolar antennas, these antennas are not suitable for such applications. It is an object of the invention to provide an improved unipol antenna,

The invention is based on the realization that the shortened portion of the lead can be arranged inside the radiator when the hollow tube is formed and the open portion of the conduit can be used to extend the first portion of the conduit. Two parts of the molars -> in the confinement are considered to be a branching line, open at one end and shorted at its other end. The power supply or antenna input points are connected to the branch points of this combined line. By appropriately selecting the position of the amplitude and frequency characteristics of the electric susceptibility of the combined current conduction, it is possible to compensate for the susceptibility of the antenna reference point across a wide frequency range, thereby conferring an advantageous ratio of standing waves in a larger band.

According to the invention, the improved unipolar antenna is provided with a resonant quarter-wavelength rod extending vertically upwardly from the ground plane, comprising a pair of inputs arranged between the ground plane and the lower end of the bar of the arrester. The shortened part of the line is connected in parallel to the input terminals, and the improvement consists in the fact that the part of the line shorted at one end is made as a ground rod extending concentrically inside the radiator rod and the shorting member is connected as 4 - 229 849 to the end portion of the earth rod and to the inner wall of the radiator rod, and another portion of the open end conduit is connected to the inlet terminals arranged as an extension of the first portion of the line.

In a preferred embodiment, the lower end of the emitter bar is connected both to the inner conductor of the supply line and to the inner conductor of the open conduit portion, and the outer conductors of the feed line and the open conduit parts are connected to the lower end of the earth rod and to the ground plane.

The combined electrical lengths of the shortened and open parts of the line are equal to the quarter length with a tolerance range of 25/0. It is advantageous if part of the open line is made as part of the coaxial cable · / z * z

For mechanical construction, it is preferred that the unipolar antenna according to the invention comprises an antenna head made of metal that determines a central bore with the arm. The mounting disk, adjacent to the arm, is arranged in the bore and connected to the external cable of the power cable and part of the open line. The central area of ​​the mounting disc is connected to the lower end of the earthing rod. The mounting disc is insulated from the emitter bar by means of a spacer sleeve of insulating material. A clamp is provided around a lower end of the emitter bar to provide connection to the inner conductor of the power cable and the open portion, and in the central bore of the antenna head there is a support brace for securing the emitter bar. 229 849

In order to increase overvoltage protection, it is advantageous if the upper end of the carrier sleeve extends over the upper face of the antenna head and the radial bar just above the end of the carrier sleeve is joined with a ring to form a spark gap with the upper face.

The unipolar antenna, manufactured in accordance with the principles described herein, has a bandwidth that is about five times wider than the conventional unipolar antenna widths. It has advantageous properties of the bandwidth used and offers improved overvoltage protection. The design of the unipolar antenna according to the invention is p-axial. The antenna is surprisingly slim compared to its wide bandwidth and has improved reliability.

An improved unipolar antenna according to the invention will now be described with reference to the accompanying drawings, in which: Figure 1 schematically illustrates the embodiment of a dipole antenna according to the invention in which a distorted length scale was used in the region of the base antenna to facilitate comprehension . Fig. Figure 2 is a top plan view of a further embodiment; and Figure 3 shows a ratio of standing waves in relation to the frequency curve of the embodiment shown in Figure 2.

The unipolar antenna shown in Figure 1 comprises a vertical emitter pattern made of a metal tube and having a length approximately equal to one quarter of the wavelength. In the embodiment of Figure 1, the ground plane 2 is formed by the action of four counterweight rods J - 6 - 229 849 directed obliquely downwards and having a length substantially equal to one quarter of the wavelength.

The antenna has a pair of input terminals 4 and JJ, the input terminal 4 of which is connected to the lower (live) end of the radiator shaft 1 k

Even to the central conductor of the power line 17 and to the central conduit 16 at its end. The other input terminal% is connected to the ground plane to the external shield of the power supply 17 and to the outer shield of the open section 16 of the line at its upper end and to the lower end of the earth rod 2 extending axially in the center line of the emitter bar i The upper end the earth wire 2 is connected via the shorting member 6 to the inner wall of the rod 1 which is formed from a hollow tube.

The earth rod 2, together with the shorting member 6 and the cylindrical inner wall of the radiator rod 1, forms a short-circuited portion of the conduit shorter than a quarter wavelength and open at its lower end, and this open portion of the line is arranged as a virtual or virtual extension of the short- . The electrically-wound tubes of the open conduit portion 16 are also less than a quarter of the wavelength, and the conduit portion 16 may advantageously be formed by a part-axial cable. The portion of the line drawn in the tube of the radiator 1, which is short-circuited at its upper end, when considered together with the open portion 16 of the conductor connected thereto, can be considered as a common combined portion of the line shorted at the upper end and opened at the lower end . This combined portion of the line has 229,949 branches at the height of the ground plane 2 and in this branch the combined part of the line is connected in parallel to the input terminals 4, The presence of this branch-wired section has a significant effect on the characteristics of the unipolar antenna. At the junction points, a part of the line is a virtually pure suscepti- on, which corresponds to the reactant component of the admittance of the reference point of the antenna.

The Susceptance portion of the lead at the tap points varies with the pitch and the slope of this change depends on the position of the tap points in the line, while the size of the susceptibility depends on the full length of the line and on the capacitance represented by the base antenna determined by the mounting dispersion capacities. The length of the combined part of the line is close to a quarter of the wavelength, and the position of the point points can be adjusted by simultaneously establishing the position of the shorting member 6 and the length of the open section 16 of the conduit, during which the length of the combined portion of the conduit should remain constantly constant.

It has been found that, in the case of suitable tapping points, the susceptibility represented by the combined portion of the line can compensate for the change of the reactant component of the antenna reference point impedance to a substantially wide frequency band, whereby the ratio of standing waveguides is relatively good in a wide bandwidth.

The antenna will have an increased working bandwidth, however the presence of the branch lines provided is a high-end acceptance outside the operating band, which practically shortens the 8,229,949 antennas in. This effect is favorable since the receiver input connected to the antenna will be protected from interfering signals of high level received outside the working band, or effectively rejects the radiation of transmitter scatter signals when connected to the antenna. By using the combined part of the line, there will be a galvanic connection between the radiator rod 1 and ground potential, thus preventing static charge of the antenna. Unlike stacked unipolar antennas, the earth rod 2 is arranged so that it is shielded inside the radiator 1 and the dynamic effect of the overflow can not cause great damage to the antenna structure.

Fig. 3 shows the ratio of standing waves in relation to the antenna frequency curve designed according to the invention for operation in the range of 33 to 38 MHz, and the curve shows that the ratio of the standing wave antenna is better than 1.5 in the 5 MHz band, which is the re-latent width bands of 14%. This bandwidth is about 5 times the bandwidth of conventional unipolar antennas.

In addition to increased bandwidth, the electrically grounded radiator has favorable off-band characteristics, the antenna according to the invention has several other preferred features to be described with reference to the exemplary embodiment shown in Figure 2. In this embodiment, the assembly is attached to an antenna head 11 made of metal, in which threaded studs with sloping beams are machined to receive counterweights. In the antenna head there is a central drilling open from the bottom and in the bore - 9 229 848 a shoulder is formed. The metal mounting disc 14 abuts against an arm that is connected to it by threaded bolts, and the mounting disc 14 is electrically connected to the lower end of the grounding rod 2. The lower end of the radiator rod 1 is isolated from the mounting 1¼ by a spacer 13 made of an insulating material.

The support sleeve 10 is disposed at the top of the central antenna head 11 and its upper end extends over the head of the antennae 11 about 2 mm. The beam of the radiator 1 is guided by the horizontal splicing of the sleeve 10 and acts as a mechanical support for the rod of the emitter 1. It is obvious that the sleeve 10 is subjected to a pressure load only when the torque of the emitter to the wind. Insulating materials easily bear such a load. The use of an insulating sleeve, subjected only to a pressure load, represents a considerable improvement in the assembly with conventional insulators, which are particularly subject to movement stress. Although the carrier sleeve 10 generates a higher capacity in the base antennas than conventional insulators designed to bend, its presence will not interfere with the embodiments of the invention,

The upper end of the open section 16 of the conduit and the power line 17 are both connected to the mounting disc 14 in such a way that the shielding of these cables is connected to the mounting disc 10,229,849 by means of the respective cable clamps 15a and 15b. The cords of these cables are both connected to the terminal 12 connected around the lower end portion of the emitter rod 1. The asymmetric connector socket 18 is mounted at the lower end of the power line 17 for disconnectable connection of the antenna cable. The bottom of the open section 16 is closed and protected by a rubber stopper 19.

A circular gap lightning arrester is mounted on the radiator rod 1, which is adjacent the upper face of the carrier sleeve 10 and is located opposite the circular upper face of the antenna head 11. The spark gap is provided with an effective overvoltage protection. With the design shown in Figure 2, the power line 17 is sufficiently protected from the pernicious effects of overvoltage.

The lower part of the outside of the radiator bar 1 is sealed by a bell 8, preventing water and humidity from flowing over the mounting disk 14. [ However, it is advisable to fill this space with the resin. The cap 21 is used to close the upper end of the radiator bar 1.

The construction design shown in FIG. 2 is advantageous for mounting the antenna because the mounting disc 14 together with the associated cable parts and the radiator bars 1 can be assembled separately to form the prefabricated product. The antenna head 11 is designed to be easily attached to the top of the antenna mast, and may be secured by a pair of screws 20. The feed line and the openings 11-229 of the guide line 16 may be extended in the inner cavity of the mast.

The unipolar antenna according to the invention has improved power, it can be easily attached, offers sufficient protection against overflow, and the design is characterized by improved reliability, reduced susceptibility to failure, damage or overcoating if these properties are compared with the properties of the conventional unipolar antennas.

Since the increased bandwidth is due to the presence of the combined branch lines, there is no longer a need to use a high-rise radiator to provide the desired bandwidth, and thus the antenna structure will be overly slim compared to its bandwidth, at the same time, reduced wind load and reduced ice cover.