RU2573715C1 - Method of forming beam pattern of double-ring digital phased antenna array - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: invention relates to antenna systems with electronic beam control and use of annular digital phased antenna arrays in mobile and stationary communication equipment. A method of forming the beam pattern of a double-ring digital phased antenna array includes: digitally processing a microwave signal; generating control signals in accordance with data of the required beam pattern and transmitting to exciting signal emitters with an amplitude-phase distribution defined in accordance with a selected criterion; the amplitude A_nm and phase φ_nm of the exciting signals are determined by minimising the function F of the mean-square deviation of the formed beam pattern R(φ) from a given distribution E(φ) of the radiation field of the antenna array, characterised by the lowest side lobe level with a given width of the main lobe, wherein the value of the amplitude A_nm is not greater than 1.

EFFECT: forming a beam pattern with the required side lobe level.

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Description

The invention relates to antenna technology, namely to antenna systems with electronic beam control and the use of ring digital phased array antennas (CFAR) in mobile and stationary communications.

A well-known way of forming the directivity pattern (ND) of an annular digital phased antenna array with a reduced level of side lobes is the choice of ring structures and placement of antenna elements (description of patent RU 2144200 C1, IPC 7 G01S 3/14, G01S 3/74, published: 10.01. 2000, description of patent RU 2310956 C1, IPC H01Q 21/06 (2006.01), published on November 20, 2007).

Known technical solutions are mainly aimed at improving the design of the antenna system and do not solve the problems of controlling the formation of DNs.

Known technical solutions for controlling the formation of MDs in antenna systems with electronic beam control, in which the amplitude-phase distribution of the output signals of the antenna elements are set in accordance with the selected criterion (description of patent RU 2287880 C2, MPK H01Q 21/29 (2006.01) H01Q 3/26 (2006.01), published 02/10/2006, patent specification RU (11) 2395141 C1, IPC H01Q 3/00 (2006.01), published July 20, 2010).

Known methods solve the problem of controlling the formation of MDs in systems with linear antenna arrays.

The objective of the invention is to control the formation of the radiation pattern in systems with double-ring digital phased array antenna.

The technical result from the use of the invention is the formation of a radiation pattern with the desired level of side lobes.

The technical result is achieved by the fact that in the method of forming a radiation pattern of a double-ring digital phased antenna array, including digital processing of the microwave signal, generating control signals in accordance with the data on the desired beam and transmitting to the emitters of exciting signals with amplitude-phase distribution determined in accordance with the selected criterion characterized in that the amplitudes A _nm and phases φ _{nm of the} exciting signals, where n is the number of the emitter in the CFAR ring, m is the ring number, determine the minimum By dividing the function F of the standard deviation of the generated radiation pattern R (φ) from the given distribution E (φ) of the radiation field of the antenna array, which is characterized by the lowest level of side lobes for a given width of the main lobe, the amplitude A _nm does not exceed 1.

The essence of the technical solution lies in the fact that the amplitudes A _nm , not exceeding 1, and the phases φ _{nm of the} signals that excite the corresponding CFAR emitters, are calculated by a special numerical algorithm that minimizes the standard deviation of the CFA pattern from the theoretical optimal one (for example, from the Dolph Chebyshev, characterized by the lowest level of side lobes at a given width of the main lobe).

In FIG. 1 shows a functional block diagram of an antenna system with a double-ring digital phased array antenna (CFAR) for implementing the method; in FIG. 2 - normalized radiation pattern of a double-ring CFAR (curve I) in comparison with the initial one, constructed on the basis of the Dolph-Chebyshev distribution (curve II) with a level of side lobes of 40 dB and a width of the main lobe of 60 ° at a level of 3 dB; in FIG. 3 a) is the normalized double-ring radiation pattern. CFAR calculated according to standard formulas [Zelkin EG, Sokolov V.G. Antenna synthesis methods. Phased arrays and antennas with continuous opening. M .: Soviet radio, 1980, p. 249-251] (curve III) with a wave number mismatch Δk = 0.1k, where k = 2π / λ is the wave number, and the Dolph-Chebyshev distribution (curve IV) with the level of the side lobes is 40 dB and the width of the main lobe is 60 ° in level - 3 dB; in FIG. 3 b) is a normalized radiation pattern calculated using an algorithm that minimizes the standard deviation from a given radiation pattern (curve V) with a wave number detuning Δk = 0.1k and a Dolph-Chebyshev distribution with a side lobe level of 40 dB and a main lobe width of 60 ° level - 3 dB (curve IV).

The double-ring CFAR consists of a control unit 1, a microwave signal generating unit 2, excitation signal generating devices 3 by the number of emitters 4. Each exciting signal generating device 3 is connected to the output of the microwave signal generating unit 2 by one input and the corresponding output of block 1 by the other input management. The output of each device 3 of the formation of the exciting signal is connected to the corresponding emitter 4, which are located on two concentric circles with the same angular pitch.

The control unit 1 can be performed, for example, similarly to the control unit described in the patent of the Russian Federation No. 1531183, MPK H01Q 3/26, published on December 23, 89, bull. No. 47. Block 2 of the formation of the microwave signal can be performed, for example, in the form of a microwave signal generator (see Markov G.T., Sazonov D.M. Antennas. M: Energy, 1975, p. 5). The device 3 of the formation of the exciting signal can be performed, for example, in the form of a multiplier (see Bratchikov A.N. et al. Active phased antenna arrays. Edited by DI Voskresensky. M.: Radio Engineering, 2004, p. 28).

The method of forming the radiation pattern of a double-ring digital phased array antenna is as follows.

To form a radiation pattern of a circular antenna array, it is necessary to specify the amplitudes A _nm and phases φ _{nm of the} exciting signals supplied to the CFAR emitters.

The signal generating unit 2 generates a microwave signal, which is fed to the inputs of the excitation signal generating devices 3. At the input of the control unit 1, the initial data about the required radiation pattern are introduced: the direction angle of the main lobe and the level value of the side lobes.

In the memory of control unit 1, sets of complex coefficients C _nm = A _nm exp (jφ _nm ) are stored. Each of the coefficients C _nm determines the amplitude and phase of the exciting signal of the corresponding emitter 4. The sets of coefficients correspond to different directions of radiation of the CFAR, the change of which is carried out with a given arbitrary angular step, and the coefficients C _nm themselves are calculated under the condition of a given level of side lobes, which is achieved by applying an algorithm that minimizes the standard deviation of the generated radiation pattern from a given one.

Block 1 generates control signals that contain digital data on the coefficients C _nm and transmits them to the corresponding device 3 for generating exciting signals, in each of which the microwave signal and the corresponding coefficient C _nm are multiplied. The exciting signals from the outputs of the forming devices 3 are supplied to the corresponding emitters 4 CFAR, the total radiation of which forms the desired radiation pattern.

The essence of the algorithm for calculating the coefficients With _nm is as follows.

The radiation pattern of a single-ring circular antenna array has the form [Watanabe. F, Goto N., Nagayama A., Yoshida G. A pattern synthesis of circular arrays by phase adjustment // IEEE Transactions on Antenna and Propagations, 1980, vol. AP-28, No. 6, pp. 857-863, Zelkin E.G., Sokolov V.G. Antenna synthesis methods. Phased arrays and antennas with continuous opening. M .: Soviet radio, 1980, p. 249-251]:

.

.

In the case of a multi-ring grating with radiation directed at a certain angle, the radiation pattern has the form

,

,

,

,

where N is the number of elements in a single-ring antenna array, M is the number of rings.

The complex coefficients C _nm are calculated on the basis of minimizing the function F of the mean square error (deviation) of the radiation pattern R (φ) of the antenna array phased at a certain angle from the desired distribution E (φ), characterized by the lowest level of side lobes for a given width of the main lobe, while fulfilling the condition | A _nm | ≤1:

,

,

where the summation is carried out over the set of angles φ _i in which the deviation of the radiation pattern from the given one should be minimal. E (φ) is a certain predetermined distribution of the radiation field of the antenna array, characterized by the lowest level of side lobes at a given width of the main lobe, for example, the Dolph-Chebyshev distribution. For a circular antenna array, it has the form [Stearns S.O., Stewart A.S. An Investigation of Concentric Ring Antennas with Low Sidelobes // IEEE Transactions on Antenna and Propagations, 1965, vol. AP-13, No. 6, pp. 856-863]:

,

,

where T _l (x) is the Chebyshev polynomial of the first kind of the lth order, ε is the ratio of the level of the side lobes to the level of the main lobe.

An example of the radiation pattern of a double-ring digital phased antenna array formed in accordance with the claimed method, as well as its comparative characteristics confirming the achievement of a technical result, are presented in FIG. 2, FIG. 3 (a), (b).

Claims (1)

A method of forming a radiation pattern of a double-ring digital phased array antenna (CFAR), including digital processing of a microwave signal, generating control signals in accordance with the data on the desired beam and transmitting emitters of exciting signals with an amplitude-phase distribution determined in accordance with the selected criterion, characterized in that the amplitudes A _nm and the phase φ _nm , where n is the number of the emitter in the CFAR ring, m is the number of the ring, the excitation signals are determined by minimizing the function F of the mean square the deviation of the generated radiation pattern R (φ) from the given distribution E (φ) of the radiation field of the antenna array, characterized by the lowest level of side lobes at a given width of the main lobe, while the amplitude A _nm does not exceed 1.

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