RU2700332C1 - Capacitive two-resonance antenna - Google Patents

Abstract

FIELD: antenna equipment.

SUBSTANCE: invention relates to antenna engineering and can be used in designing transceiving antenna devices for VHF radio communication equipment of frequency band. Antenna comprises two capacitance elements developed in space, formed by three current-conducting surfaces, one of which is common and grounded, two inductance coils, each of which is connected to its capacitive element so that a system of two coupled oscillatory circuits is formed, tuned to different operating frequencies, and a matching device, two outputs of which are connected to different inductance coils, and the input is connected to a feeder line. At that, each inductance coil is provided with a dielectric threaded nut and a threaded dielectric core with a short-circuited copper ring along the core circumference, which during core rotation moves inside coil, which leads to smooth change of its inductance and enables to fine-tune resonant frequencies of antenna circuits within required limits.

EFFECT: technical result consists in ensuring constancy of structurally specified working frequencies of a capacitive two-resonant VHF antenna when installed on a permanent operation object by enabling their rapid adjustment.

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Description

The invention relates to antenna technology and can be used to create transceiver capacitive antenna devices for mobile radio communication equipment VHF frequency range.

Well-known analogs are a small-sized capacitive antenna with a matching inductor (see patent for the invention of the Russian Federation No. 2470424, M. class. H01Q 9/04, published on December 20, 2012), as well as a capacitive two-resonance antenna for the VHF frequency range (see patent for the invention of the Russian Federation No. 2610387, M. C. H01Q 9/04, publ. 02/09/2017), selected as a prototype, containing three conductive surfaces, two inductors and a matching device.

In this prototype, two conductive surfaces, together with a third common grounded conductive surface, form two capacitive elements deployed in space, each of which is connected in series with a corresponding inductance coil. In this case, a system of two connected oscillatory circuits (antenna circuits) is formed, which can be tuned to different frequencies depending on the frequency of the emitted (received) electromagnetic signal. Thus, the working frequencies of the antenna are the resonant frequencies of the antenna circuits, which are set constructively and are determined by their inductance and capacitance.

where F _p is the resonant frequency of the antenna circuit;

L, C - inductance and capacitance of the antenna circuit, respectively.

When such an antenna is installed on an object of continuous operation, parasitic capacitances may additionally be introduced into the antenna circuits due to the influence of surrounding objects and the underlying surface, which, in accordance with (1), can lead to mismatch of the connected loops and to a change in the structurally set operating frequencies of the antenna. The mismatch of the frequency of the input signal to the resonant frequency of the antenna circuit will lead to a significant decrease in the antenna efficiency in radiation and, as a result, to a reduction in the radio range. Therefore, during the initial installation of the antenna at the object of constant operation, it becomes necessary to quickly adjust its resonant frequencies.

As follows from (1), the resonant frequency of the oscillatory circuit can be changed by selecting the capacitance or inductance. However, the capacitance value is rigidly set by the design of capacitive elements, and the antenna circuit inductance coil at the VHF frequencies has only a few turns, which does not allow the use of well-known methods and devices for tuning inductance.

For example, the introduction of a ferromagnetic core into a coil with a small number of turns will lead to an unacceptably sharp change in the total inductance and, as a result, to the inability to provide fine tuning of the resonant frequency of the circuit in a limited frequency range. In addition, at a high frequency in the radiation mode, significant losses will occur in the core.

The construction of a variable inductance coil according to the principle of a variometer is not justified due to the complexity and "bulkiness" of the design in comparison with the dimensions of the antenna itself.

The use of a matching inductor described in the patent for the invention of the Russian Federation No. 2470424, does not lead to the achievement of a technical result, since it allows you to change only the input impedance of the antenna and practically does not affect the resonant frequency of the antenna circuit.

The technical result of the invention is to ensure the constancy of the structurally specified operating frequencies of a capacitive two-resonant VHF antenna when installing it at an object of constant operation by creating the possibility of their operational adjustment.

The technical result can be implemented in a capacitive two-resonant VHF antenna, containing two capacitive elements deployed in space, formed by three conductive surfaces, one of which is common and grounded, two inductors, each of which is connected to its capacitive element so that a system of two coupled oscillatory circuits tuned to different operating frequencies, and a matching device, two outputs of which are connected to different inductors, and the input is connected n with feeder line.

The technical result is achieved by the fact that a dielectric nut with a thread and a threaded dielectric core with a short-circuited copper ring around the circumference of the core, which during rotation of the core moves inside the coil, is introduced into each inductor, which leads to a smooth change in its inductance and allows for fine tuning of the resonant frequencies of the antenna contours within the necessary limits.

The electrical circuit of the proposed antenna and an example of the design of the tuning elements are shown in FIG. 12.

In FIG. 1 are shown:

1.1, 1.2, 1.3 - conductive surfaces of capacitive elements;

2.1, 2.2 - inductors with tuning elements;

3 - matching device.

In FIG. 2 shows the design of the tuning elements installed in the inductors 2.1 and 2.2 (see Fig. 1):

2.3, 2.4 - threaded cores;

2.5, 2.6 - copper rings;

2.7, 2.8 - dielectric nuts.

The operation of the claimed antenna with elements for adjusting its operating frequency is as follows.

In the radiation mode from the transmitter on the feeder line to the antenna through the matching device 3 (see Fig. 1) the voltage of a signal of one or another high frequency is supplied. Resonance occurs in the antenna circuit, the tuning frequency of which coincides with the frequency of the input signal. In this case, between the conductive surfaces 1.1 and 1.2 or 1.3 and 1.2 (see Fig. 1) of the capacitive element of the corresponding antenna circuit that are deployed in space, an alternating high-frequency voltage arises, which is Q times the input voltage (Q is the quality factor of the antenna circuit). A high-frequency electric field acting between conductive surfaces induces bias currents in the surrounding space, the circulation of which leads to the appearance of electromagnetic radiation.

In the frequency adjustment mode, the threaded core 2.3 or 2.4 is rotated (see Fig. 2), as a result of which the snapped copper ring 2.5 or 2.6 (see Fig. 2) is linearly moved inside the inductor 2.1 or 2.2 (see Fig. 2 ) respectively. The interaction of the magnetic field of the inductor and the magnetic field caused by induced in the short-circuited copper ring 2.5 or 2.6 EMF leads to a change in the inductance of the coil 2.1 or 2.2, and the movement of the copper ring 2.5 or 2.6 leads to a smooth change in the operating frequency of the antenna.

Industrial applicability of the device is achieved by the fact that for its manufacture can be used widespread materials and technologies. Threaded cores (2.3, 2.4) and dielectric nuts (2.7, 2.8) can be made of any dielectric material (ebonite, fiberglass, ABS plastic, etc.) by turning. The copper ring (2.5, 2.6) can be made of thin sheet copper of grades M, P or T by soldering.

Claims (1)

A capacitive two-resonant VHF antenna containing three conductive surfaces, one of which is grounded, and the other two form in pairs two capacitive elements deployed in space, two inductors, one output of each coil is connected to one of two conductive surfaces, and a matching device, outputs which are connected to the second terminals of the inductors, while one terminal of the matching device is grounded, and the input is connected to the center conductor of the feeder line, characterized in that each A threaded dielectric nut and a threaded dielectric core with a short-circuited copper ring around the core circumference are introduced into the inductance coil.

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