JPH0770902B2 - Antenna device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention controls SINR at the output end of an array antenna by controlling a phase shifter connected to each element antenna.
The present invention relates to an antenna device for maximizing (a ratio of [signal wave] to [unwanted wave + internal noise]).

[Conventional technology]

FIG. 7 shows, for example, Technical Report of IEICE, AP-84-10,
17 is a diagram showing a configuration of a conventional antenna device shown in p.17 to p.24, "A direction-constrained adaptive array in which only phase is controlled" Takao, Kikuma, and Ueda.

In the figure, Ea1, Ea2, ..., EaN are element antennas, Ps1, Ps2,
…, PsN is a phase shifter, 1 is a power combiner, 2 is a receiver, 3 is a phase shifter controller, 4 is a control processor, Ca1, Ca2,…, CaN is a coupler, 5 is a phase / amplitude detector. is there.

Next, the operation will be described. Element antenna Ea1, Ea2,…, E
The phase of the radio wave received by aN is changed by the phase shifters Ps1, Ps2, ..., PsN. Next, the power combiner 1 combines the output signals of the respective phase shifters. The combined signal is transmitted to the receiver 2. When performing normal beam scanning, the control processor 4 calculates the set amount of each phase shifter required for beam scanning, and the phase shifter control device 3 controls each phase shifter according to the calculation result of the control processor 4. Beam scanning is performed by setting the initial phase. The operation described above is the operation of a normal phased array antenna.

On the other hand, when there are unnecessary radio waves and clutter, it is necessary to maximize the SINR at the output end of the phased array antenna. At this time, the following operation is performed. The radio wave whose phase has been changed by the phase shifter is taken out by the couplers Ca1, Ca2, ..., CaN and transmitted to the phase / amplitude detector 5. If the respective input signals at this time are ₁ , ₂ , ..., _N , the control processor 4 at the next stage of the phase / amplitude detector 5 should minimize the following function value based on the nonlinear optimization method. Find the setting change amount (qi) of the phase shifter.

However, in the equation (1), a _i is known as the amplitude of the incident electric field in the arrival direction of the desired wave of the i-th element, and the set variation q
_i indicates the amount of change from the initial phase setting amount for performing normal beam scanning of each phase shifter. The first term represents the output power, and the second term represents the constraint condition that the level of the main beam is maintained even if the phase is changed by q _i from the cophase state.
Therefore, by obtaining the minimum value of (1) for setting the amount of change q _i, the main beam level maintaining of determined set change amount q _i that removes unnecessary waves.

The operation described above is based on the direction-constrained output power minimization method in the above-mentioned document.

[Problems to be solved by the invention]

Since the conventional antenna device is constructed as described above, each of the input signals _{1, 2} of the pre-operation, ..., _N, as shown in FIG. 8 vectorially, also gave a phase change amount q _i Each input signal after Becomes vectorally as shown in FIG. The radiation pattern of the antenna during operation is shown in FIG. 10, in which the solid line shows the zero point formation pattern and the broken line shows the initial pattern.
FIG. 11 shows zero (Nal; N) in the radiation pattern shown in FIG.
ull) shows an enlarged view of the circumference of the point forming angle. However, FIG. 10 shows that a 5-bit quantization phase is given as the set phase. In FIG. 11, an arrow a indicates the angle of the formed zero point, and an arrow b indicates the angle at which the unwanted wave actually arrives. Originally, in order to minimize the received power of the unwanted wave, The zero point obtained by the calculation using the input signal must be formed at the angle at which the unwanted wave actually arrives. However, as shown in FIG. 10, when the set phase amount q _i calculated is quantized, the set phase amount given to the phase shifter becomes coarse. Therefore, as shown in FIG. 11, since the formation angle of the zero point obtained by the calculation and the angle at which the unwanted wave actually arrives do not match, SINR deteriorates. Therefore, in the above-mentioned literature, the setting change amount
When q _i is quantized, in order to obtain a good SINR,
It is concluded that an 8-bit phase shifter is necessary, but in the current system, a 5-bit phase shifter is practically used from the viewpoint of the feasibility and economical efficiency of the phase shifter and the phase shifter control unit. ing.
Therefore, it is necessary to obtain a good SINR even with a small number of bits.

The present invention has been made in order to solve the above problems, and a wide null angle width can be obtained, and when the set change amount of the phase shifter is quantized, it can operate favorably with a small number of bits. The purpose is to obtain an antenna device.

[Means for solving problems]

An antenna device according to the present invention is a linear array antenna device in which a phase shifter connected to each element antenna is controlled to maximize SINR, wherein i (i = 1 to N of each element antenna) ) -Th element antenna, the phase of the input signal S _i obtained is ± Δφ = (2π / λ) · d (i−1) sin (± α) (where λ: wavelength, d: element interval) Α is a constant determined from the null angle width) and a pseudo signal to which a bias phase of ± Δφ _i is added is obtained, and SINR is maximized based on the phase and amplitude of both the input signal and the pseudo signal. A calculation means for calculating the set phase given to the above phase shifter is provided to obtain a wide null angle width and to obtain a good SINR even when the set change amount of the phase shifter is quantized. Is.

[Action]

The antenna device according to the present invention is, in a linear array antenna device, an input signal obtained corresponding to the i (i = 1 to N) -th element antenna of each element antenna obtained by the phase / amplitude detector by the arithmetic processor. In the phase of S _i , ± Δφ _i = (2π / λ) d (i-1) sin (± α) (where λ: wavelength, d: element spacing, α: constant determined from null angle width) Then, a pseudo signal is created by adding a bias phase of ± Δφ _i , and the calculation processing is performed by this pseudo signal and each of the input signals described above. Therefore, a wide null angle width is obtained and the set change amount of the phase shifter is quantized. Even if it does, a good SINR can be obtained.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, the same reference numerals as those in FIG. 7 denote the same parts, and 6 is an arithmetic processor.

The apparatus of this embodiment configured as described above will be described with reference to the flowchart of FIG. Where the coupler Ca1, Ca
2,…, _{1 for} each input signal extracted by CaN
₂ , ..., _N. Each of the input signals ₁ , ₂ , ..., _N is transmitted to the phase / amplitude detector 5 (step 10 in FIG. 3), and then the arithmetic processor 6 applies a bias of Δφ _i ( _{i to} N) to each input signal. The phase is given (step 11). For example, if the bias phase is ± Δφ _i , the signal obtained by this processing is as shown below.

The state of each signal vector in this case is shown in FIG. Here, ± Δφ _i is represented by the following equation in the case of a linear array having an element spacing d, for example.

However, λ: wavelength d: element spacing α: constant determined from null angle width By giving such a bias phase of ± Δφ _i , an unwanted wave virtually arrives at an angle adjacent to the unwanted wave arrival angle. This is shown to the arithmetic processor 6, and the arithmetic processor 6 performs arithmetic operation to form a plurality of zero points at an angle adjacent to the unwanted wave arrival angle. Therefore, a wide null angle width can be obtained, and even if there is an error at the time of detecting each input signal or a setting error of the phase shifter, the minimum unnecessary wave received power can be obtained and a good SINR can be obtained.

That is, the arithmetic processor 6 performs the arithmetic operation for obtaining the minimum value of the setting change amount q _i of the phase shifter of the evaluation function f shown below in step 12 by a non-linear optimization method such as the steepest descent method.

However, a _i represents the amplitude of the incident electric field of the i-th element. The first term, the second term, and the third term of the equation (6) are (2)
This is a term for obtaining the minimum value of the combination of the signals shown in equations (3) and (4), and the fourth term is a term for protecting the signal wave.

The operation result of the operation processor 6 obtained in this way controls the phase shifter control device 3 via the control processor 4 (not shown in FIG. 3), and the phase shifter control device 3 controls each phase shifter. Control the phaser (step 13). Therefore, according to the apparatus of this embodiment, a wide null angle width can be obtained by giving a bias phase to each input signal.

Fig. 4 shows a linear array antenna in which 30 element antennas are linearly arranged at half-wavelength intervals and an amplitude distribution of -30 dB is applied. Using this antenna device, unwanted waves arrive from -14 °. This is the radiation pattern obtained as a result of the simulation calculation under the assumption.

Further, FIG. 5 shows q _i calculated by the arithmetic processor in the above calculation model. As shown in this figure, when the excitation phase is quantized by 5 bits, the bits do not change in the conventional method, and no change appears in the radiation pattern even if the calculation is performed. Then, even when the quantization of 5 bits is performed, a bit change occurs and a radiation pattern changes. That is, FIG. 6 shows a radiation pattern obtained as a result of simulation calculation when the excitation phase calculated by the control processor in the above calculation model is quantized into 5 bits, and a wide null angle width is obtained.

〔The invention's effect〕

As described above, according to the present invention, in the linear array antenna device, the input signal obtained corresponding to the i (i = 1 to N) th element antenna of each element antenna obtained by the phase / amplitude detector In the phase of S _i , ± Δφ _i = (2π / λ) d (i-1) sin (± α) (where λ: wavelength, d: element spacing, α: constant determined from null angle width) A bias signal of ± Δφ _i is added to obtain a pseudo signal,
Since the calculation processing is performed based on both the pseudo signal and each of the above-mentioned input signals, a wide null angle width can be obtained, and even if the setting change amount of the phase shifter is quantized, it is preferable.
There is an effect that SINR can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an antenna device according to an embodiment of the present invention, and FIG. 2 is a diagram showing each input signal vector and each input signal vector when a bias is applied to each input signal,
FIG. 3 is a diagram showing a control flowchart of the present antenna device, FIG. 4 is a diagram showing a radiation pattern by the present antenna device, FIG. 5 is a diagram showing a comparison of excitation phases with a conventional example, and FIG.
FIG. 7 is a diagram showing a radiation pattern when a digital phase shifter is used in the present antenna device, FIG. 7 is a diagram showing a conventional example, and FIG. 8 is a diagram showing input signal vectors when a normal beam scanning phase is given. Fig. 9 is a diagram showing each input signal vector when an excitation phase is given, Fig. 10 is a diagram showing a radiation pattern by a conventional device, and Fig. 11 is a diagram showing the radiation pattern shown in Fig. 10. It is the figure which expanded the circumference | surroundings of a zero formation angle. Ea1, Ea2,…, EaN …… Element antenna, Ps1, Ps2,…, PsN ……
Receiver, 3 ... Phase shifter controller, 4 ... Control processor, 5 ... Phase / amplitude detector, 6 ... Arithmetic processor. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. N pieces (N ≧ 2) arranged side by side on a straight line.
Element antenna, a phase shifter connected to each of these element antennas, a power combiner that combines the output signals of the phase shifters, and a phase shifter control device that controls the set amount of the phase shifter. A coupler for extracting a signal S _i corresponding to the i (i = 1 to N) th element antenna of each element antenna between each phase shifter and the power combiner; For the phase / amplitude detector to be received and the phase of each input signal S _i detected by the phase / amplitude detector, ± Δφ = (2π / λ) · d (i−1) sin (± α) λ: Wavelength d: Element spacing α: Pseudo signal α ₁ to which a bias phase of ± Δφ _i , which is a constant determined from the null angle width, is added
Sα _N is generated, and the ratio of (signal wave) to (unwanted wave + internal noise) is maximized based on the phase and amplitude of both the input signals S _{1 to} S _N and the pseudo signals Sα _{1 to} Sα _N. And a calculating means for calculating a set phase to be given to the phase shifter.