RU2713163C1 - Method of constructing an omnidirectional annular antenna array and an antenna that implements it - Google Patents

Abstract

FIELD: radio equipment.

SUBSTANCE: invention relates to radio engineering and is intended, in particular, for use in systems of mobile and fixed communication: land, air, sea in meter and decimeter ranges. Method of constructing an omnidirectional annular antenna array, in which antenna elements (AE) are placed with a fixed phase center such that distance between phase centers of neighboring AE does not exceed half of the shortest wavelength in the operating band, AE is selected electrically as full-size and galvanic connection is made between AE so that AE have common continuous geometrical contour of radiating part are electrically extended and traveling-wave mode is set in them. Antenna comprises AE 1 with fixed phase centers forming an omni-directional antenna array, wherein AE 1 are in-phase-fed, made in the form of double-lead spiral antennas, each AE 1 is galvanically connected to its adjacent end and distance between phase centers AE 1 is not more than half of the smallest wavelength in the operating range. AE 1 can be made in form of concave ellipsoid. Antenna can be equipped with reflector.

EFFECT: providing a wide band of operating frequencies while maintaining efficiency and small overall size.

5 cl, 7 dwg

Description

The invention relates to the field of radio engineering and is intended, in particular, for use in mobile and stationary communication systems: land, air, sea in the meter and decimeter ranges.

A known method of transmitting signals through an omnidirectional ring log-periodic antenna array of vertical polarization (patent for invention RU2587495, IPC H01Q11 / 10, H01Q21 / 20, published on 06/20/2016), based on the division of the full working frequency band into two transmission frequency ranges, with in this case, for each of the ranges, their sections of the antenna array are allocated, the transmission channel is assigned to the transmitted signals, the assigned channels are distributed among the transmission ranges and the signal is transmitted through the corresponding sections of the antenna array. The range of operation of the section is determined by the maximum radius of removal of the phase center along the feeder line of log-periodic antenna elements (hereinafter LPAE). Thus, the broadband of the system is due to a decrease in the effect of an increase in the electric radius of the lattice due to the scaling of the LPAE for each of the ranges of the full working band. The disadvantage of this method is the complicated feeder system, requiring separate power addition devices and beamforming for each of the ranges, and in addition, frequency separation devices. The use of log periodic antennas as antenna elements (hereinafter referred to as AEs), characterized by a moving phase center, moving with increasing frequency from long to short emitters of the LPAE, entails a greater change in the electric radius of the grating than when using AEs with a fixed (fixed) phase center.

The known method CSA (current sheet array) ([1] p. 583-586), adopted as a prototype, providing for the creation of an antenna array in the form of a system of strongly coupled AEs. The antenna system (array), constructed by the CSA method, is characterized in that it has a greater broadband in the low frequency region compared to its individual component. The method includes placing AEs both in the vertical (relative to the screen) and horizontal (mutual) planes, so that the distance between adjacent AEs does not exceed half the shortest wavelength in the operating range, which in turn ensures the absence of side minima / maxima of the diagram directivity (hereinafter NAM) of the lattice. The system is designed so that the capacitive coupling between the AEs ensures matching in the lower part of the operating range of the antenna array where the AE does not provide (in view of its small electrical size (the product of the wave number (ratio 2π to wavelength) and half the maximum overall size of the antenna element, is a value of not more than 0.5 [1] p. 475) matching with the path The disadvantage of this method is to reduce the gain (hereinafter KU) in relation to the efficiency (hereinafter referred to as efficiency), due to Pasanen of the energy supplied to the AE in the strong capacitive coupling.

Known combined "quasicarrier" antenna (patent for invention RU2469448, IPC H01Q19 / 00, published December 10, 2012) containing 4 centrally-mounted symmetrical vibrators (AEs) made of two square-frame elements with open conductors in the lateral corners and closed conductors in the upper and lower corners. The implementation of the square-frame AE curved relative to the center point of the circumference of the square-frame web entails an increase in the electric radius of the AE grating, which, in turn, reduces the upper boundary of the antenna operating range. The implementation of AE in the form of square-frame elements is a range solution, which also limits the working band of the antenna.

A known antenna with a reflector (patent DE102005003685, IPC H01Q 9/28, published 03.08.2006), operating in the range from 180 to 600 MHz, adopted as a prototype, containing at least one reflector and at least one emitter (antenna element) located at a certain distance from the reflector, while the emitter is dipole and consists of two elements facing each other, which are a section of a triaxial ellipsoid. Thus, the emitters are in-phase and have a fixed phase center. The most favorable operating mode is achieved using eight emitters. Work in a wide frequency band is ensured not only due to the broadband matching of the emitter, but also due to the mutual arrangement of the AE and the distance between them (to ensure the proper electric radius of the antenna array, required to maintain the quasi-directional shape of the radiation pattern (hereinafter referred to as the radiation pattern). The disadvantage of the antenna is that in order to achieve the most favorable operating mode, it is necessary to use a large number of emitters (eight), which leads to a decrease in system efficiency (power is divided into 8 channels) and a relatively large overall size (according to clause 5 of the description, the optimal size of the antenna system from eight AE is about 800 mm, i.e. for a frequency of 180 MHz, approximately 0.48 wavelength).

The technical result to which the invention is directed is to provide a wide band of operating frequencies while maintaining efficiency and small overall size.

To achieve the specified technical result, a method of constructing an omnidirectional ring antenna array, in which AEs with a fixed phase center are placed so that the distance between the phase centers of adjacent AEs does not exceed half the smallest wavelength in the operating range and organize a connection between AEs with matching ring antenna array with a feeder path at the longest wavelength of the operating range, the AE is electrically electrically full-sized (i.e. size larger than 0.5 [2]), and the connection between the AEs is galvanic in such a way that the AEs have a common inextricable geometric contour of the radiating part, are electrically elongated (ie, the electric size has increased), and the traveling wave mode is established in them.

The specified technical result in an antenna containing AEs with fixed phase centers, forming an omnidirectional antenna array, while the AEs are fed in-phase is achieved due to the fact that each AE is electrically connected to its neighboring end, the AEs are made in the form of double-helical antennas and the distance between the AE phase centers no more than half of the smallest wavelength in the operating range. AE can be made in the form of a concave ellipsoid. For optimal operation, the number of AEs is selected equal to three. The antenna can be equipped with a reflector.

The invention is illustrated by drawings, where in FIG. 1 shows a general view of the antenna; figure 2 is an example of a structure comprising an antenna; in FIG. 3 - dependence of the overlap coefficient of the annular antenna array on the number of AEs; in FIG. 4 is a general view of an antenna whose AE is made in the form of concave ellipsoids; in FIG. 5 - shape of the pattern in the azimuthal plane at frequencies of 300, 500 and 645 MHz; in FIG. 6 - the shape of the pattern in the azimuthal plane at frequencies of 1000, 1100 and 1200 MHz; 7 is a graph of the dependence of the SWR (standing wave coefficient) of the antenna from isolated and self-loaded AE.

The antenna is an in-phase equidistant annular antenna array AE 1 with fixed phase centers (see Fig. 1). To ensure operability, the antenna may also contain a power divider and feeders (not shown in Fig., Feeders can be excluded from the design by directly connecting the AE 1 to the power divider), or the antenna may contain separate feeder paths (by the number of AE 1) that are connected to the receiver / transmitter. AE 1 are powered in phase and each AE 1 is galvanically connected by its end to a neighboring one. 1 also shows the radiating slit 2 of the AE 1 and the microstrip line 3. In FIG. 2 shows an example of a design based on the presented antenna, in which a dielectric frame 4, a metal base 5, a metal cover 6, a radio-transparent casing 7, a metal housing 8, and a mount to an antenna mast device 9 are additionally inserted.

As AE 1 can be used magnetic (slotted) or electric emitters with fixed phase centers. An antenna including AE 1 in the form of two-way helical antennas (with circular polarization) is considered as a specific implementation example.

The number and relative position of AE 1 determine the broadband antenna in the sense of maintaining the quasidirectional shape of the beam in the azimuthal plane. Moreover, the broadband of the annular antenna array is limited not only by the broadband of AE 1, but also by the mutual removal of the phase centers of AE 1. This is due to the following:

To maintain circular polarization, the largest wavelength of the operating range is associated with the maximum overall size of AE 1 by the following relation [5]:

(1)

(1)

where 2A is the overall size of the antenna element;

– длина волны, соответствующая нижней рабочей частоте антенны.

- the wavelength corresponding to the lower working frequency of the antenna.

The upper working frequency (corresponding to the shortest wavelength of the working range) is limited by the fact that with increasing frequency the electric distance between the phase centers of AE 1 also increases, which in turn causes the organization of side maxima / minima in the azimuthal pattern and, consequently, the deterioration of its uniformity. According to [3], the distance between the phase centers of AE 1 should not exceed half the wavelength, i.e. The following expression is valid:

(2)

(2)

where R is the electric radius of the annular antenna array;

N is the amount of AE 1;

– длина волны, соответствующая верхней рабочей частоте антенны.

- the wavelength corresponding to the upper working frequency of the antenna.

For geometric reasons, the radius of the ring antenna array is defined as

(3)

(3)

Accordingly, the coefficient of overlap of the operating range, equal to the ratio of the highest frequency of the range of operating frequencies to the lowest frequency of the same range, is determined by the following expression:

(4)

(4)

where k is the coefficient of overlap of the working frequency range.

According to FIG. 3 (dashed line) the largest overlap coefficient (corresponding to the widest range of operating frequencies of the antenna) is provided when the number of AE 1 is equal to three. At the same time, during omnidirectional operation, the equivalent power radiated into space will turn out to be greatest with the smallest amount of AE 1. The ring gain will have the greatest gain while maintaining the quasi-directional beam pattern with the least number of elements. As shown by the calculation and field experiments, two AE 1 do not provide sufficient uniformity of the pattern and the preservation of circular polarization of the entire annular antenna array. Thus, the highest gain while maintaining the quasi-omnidirectional antenna pattern will be achieved by choosing the number of AE 1 equal to three.

When the minimum AE 1 is reached, their even or odd number determines the broadband according to the criterion of omnidirectionality of MD. The shape of the pattern in the azimuthal plane can be determined according to (5) [4]:

(5) $$F(\phi )={{\displaystyle \sum _{n=1}^{\mathrm{<figure-callout\; id="2"\; label="N\; e\; i"\; filenames="00000009.png"\; state="\{\{state\}\}">N\; </figure-callout>}}e}}^i$$

(5)

where F (φ) is the unnormalized pattern of the equidistant annular antenna array along the azimuthal angle φ;

n = 1, ..., N is the serial number of the AE;

λ is the working wavelength.

The calculated values of the overlap coefficient (the lower boundary of the operating range is selected according to (1), the upper one from the condition for maintaining uniformity (unevenness of not more than 3 dB) of the DN determined (5)) is shown in FIG. 3 solid line.

The analysis of FIG. 3 (solid line) shows that the largest overlap coefficient corresponds to an odd number of AE 1 (since with an even number of AE 1 and their equidistant placement in the annular array, the number of antiphase field strength vectors is the same and they cancel each other out, for an odd number of AE 1 remains uncompensated field strength vector).

Based on the foregoing, the number of AE 1 should be minimal and odd to ensure the greatest broadband while maintaining the quasi-directional shape of the antenna beam, which is confirmed by the studies, the results of which are shown in FIG. 5, 6.

Each AE 1 is self-loaded, i.e. its end is galvanically connected to the neighboring AE 1, which provides not only the electrical extension of AE 1, but also the traveling wave mode in the element for the low-frequency region of the working frequency range, which in turn extends the lower boundary of the latter. This allows you to reduce the overall size of the AE 1, to reduce the electric radius of the grating, and thereby increase the upper frequency of the operating range of the antenna.

The dielectric frame 4 is used to provide structural rigidity. The metal cover 6 and the metal base 5 are used to shield the signal reflected from the underlying surface and other nearby metal structures. Radio-transparent casing 7 is used to protect against environmental factors. A power divider or feeder paths can be placed in the metal housing 8. Mounting to the antenna mast device 9 allows you to install the antenna on the object.

In Fig. 7, the solid line shows a graph of the dependence of the SWR of a lattice of self-loaded AEs on frequency, the line with dots shows a graph of the dependence of the SWR of an array of isolated AEs on frequency. According to the experimental data and analysis of Fig. 7 applied in the invention, the principle of self-loading of AE 1 allows you to expand the operating range in the low frequency region by about 1.2 times.

To bring the phase centers closer together and increase the upper frequency of the operating range, the AE 1 shape is chosen concave (for example, in the form of an ellipsoid) (see Fig. 4).

To increase the gain, the antenna may include a reflector (located in the center of the annular antenna array).

The antenna works as follows.

As an example, an antenna comprising a power divider and feeders will be considered. In-phase signal conditioning from the transmitter to AE 1 is provided by a power divider and feeders. The number of feeders and outputs of the power divider corresponds to the number of AE 1. The power divider separates the signal from the transmitter and through the feeders the separated equal-amplitude and common-mode signals are sent to the AE. The principle of operation of AE 1 is based on constructing it as a quasi-self-complementary two-way helical slot antenna with a feeder device in the form of a microstrip line 3 of variable width. Each AE 1 has a galvanic connection with the neighboring AE 1 (due to the common continuous contour of the radiating slit 2), which provides not only the electrical extension of the AE 1, but also the traveling wave mode in the element for the low-frequency region of the operating frequency range. When a signal is applied to the input of AE 1, the microstrip lines 3 excite the radiating slots 2 of AE 1. In this case, a quasi-directional beam pattern is formed, which is determined by the equal-amplitude and common-mode distribution of the signal, the equidistant placement of AE 1 and the choice of their number.

Based on the proposed solution, a prototype with a flat square AE 1 of a printed version with a side size of 270 mm (0.27 of the longest wavelength of the operating range) was manufactured, providing operation in the range from 300 to 1100 MHz (see Fig. 5,6,7 )

The method of constructing an omnidirectional ring antenna array is as follows.

At the first stage, type AE 1 with a fixed phase center is selected. As AE 1 can be used both magnetic and electric emitters, as dipole, and spiral or other. The choice of type AE 1 is made on the basis of its own directivity, gain, and to provide a quasidirectional shape of the grating pattern. AE 1 is selected electrically full-size (2πa / λ> 0.5 ([1] p. 476]) to maintain high efficiency and circular polarization in the low-frequency range of the operating range.

To ensure a quasidirectional shape of the antenna beam in the azimuthal plane of AE 1 is placed so that the distance between the phase centers does not exceed half the wavelength in the operating range (and, accordingly, the electric radius of the grating satisfies expression (3)).

The number of AE 1 is chosen to be minimal and determined based on the required antenna gain (to ensure the highest efficiency and depending on the type of AE 1). To increase the upper frequency of the operating range, the number of AE 1 is chosen odd.

A galvanic connection is made between each neighboring AE 1, so that AE 1 have a common inextricable geometric contour of the radiating part, which ensures electrical extension of AE 1 and the traveling wave mode, which, in turn, extends the lower boundary of the operating frequency range while maintaining efficiency.

To reduce the electric radius of the grating and the corresponding additional expansion of the upper boundary of the operating frequency range, the shape of AE 1 is chosen concave (for example, in the form of an ellipsoid (see Fig. 4)).

Next, each AE 1 is connected to a source / receiver of energy (for example, to a transmitter / receiver), for example, using a power divider with feeders or using separate feeder paths and transmit / receive signals.

Thus, the presented method of constructing an omnidirectional annular antenna array and an antenna built on its principle make it possible to provide a wide band of operating frequencies while maintaining efficiency and a small overall size.

Sources of information:

1. Constantine A. Balanis Modern antenna handbook. - Published by John Wiley & Sons, Inc., 2008.

2. “Handbook of antenna technologies” Published by Zhi Ning Chen - Springer reference 2016-3473p. from. 198, 201.

3. Kocherzhevsky G.N., Erokhin G.A., Kozyrev N.D. Antenna-feeder devices: a textbook for universities. - M .: Radio and communications, 1989.

4. Shortwave antennas. Aizenberg G.Z., Belousov S.P., Zhurbenko E.M., Cliter G.A., Kuramov A.G. Edited by G.Z.Aisenberg - 2nd, revised. And add. - M .: Radio and communications, 1985

5. Yurtsev O.A., Runov A.V., Kazarin A.N. Spiral antennas. - M .: Owls. Radio, 1974

Claims (5)

1. A method of constructing an omnidirectional ring antenna array, in which antenna elements with a fixed phase center are placed so that the distance between the phase centers of adjacent antenna elements does not exceed half the smallest wavelength in the operating range and organize communication between antenna elements with matching ring antenna array with a feeder path at the longest wavelength of the operating range, characterized in that the antenna element is electrically selected full-size, and the connection between the antenna elements is galvanic in such a way that the antenna elements have a common inextricable geometric contour of the radiating part, are electrically elongated and the traveling wave mode is set in them. 2. An antenna containing a set of antenna elements with fixed phase centers forming an omnidirectional antenna array, while the antenna elements are fed in-phase, characterized in that each antenna element is galvanically connected to its adjacent end, the antenna elements are made in the form of two-way spiral antennas, and the distance between the phase centers of the antenna elements is not more than half the smallest wavelength in the operating range. 3. The antenna according to claim 2, characterized in that the antenna elements are made in the form of a concave ellipsoid. 4. The antenna according to claim 2 or 3, characterized in that the number of antenna elements is three. 5. The antenna according to one of paragraphs. 2, 3 or 4, characterized in that it is equipped with a reflector.

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