JP2004153854A - Array antenna control apparatus and control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To calculate an optimum reactance value for an ESPAR antenna at high speed. <P>SOLUTION: In this array antenna which comprises a radiation element 6 to which a radio signal is supplied and at least one parasitic element 7 positioned at a predetermined distance d away from the radiation element 6 to which the radio signal is not supplied, a variable reactance element 23 is connected to the parasitic element 7 and the directional characteristic of the array antenna is varied by changing the reactance value x<SB>i</SB>of the variable reactance element 23. A controller 100 repeatedly calculates the reactance value of the variable reactance element 23 by using the dynamic equation of a higher order algorithm based on an azimuth angle representing the arrival direction of a desired input radio signal, whose calculation is carried out to minimize an evaluation function based on an array antenna gain which is a function of both the reactance value and the azimuth angle. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a control device and a control method for an array antenna having a plurality of antenna elements.

  As an antenna aiming for analog adaptive beamforming at low cost, it is provided with one feed antenna element and at least one parasitic reactance element, and by electronically changing the reactance value of the parasitic reactance element, an array antenna is formed. There has been proposed an electronically controlled steerable passive array radiator antenna (hereinafter referred to as an ESPAR antenna) that changes the directional characteristics (for example, see Non-Patent Document 1).

  The microwave beam forming using the ESPAR antenna of the conventional example has a possibility that it can be developed into an adaptive wireless user antenna instead of the conventional digital beam forming (DBF) (for example, see Non-Patent Document 2). . In this ESPAR antenna, by controlling the reactance value loaded on the parasitic element, continuous beam scanning and null scanning with respect to all azimuth angles can be realized.

T. Ohira et al., "Electronically steerable passive array radiator antennas for low-cost analog adaptive beamforming", Proceeding of IEEE International Conference, Phased Array System Technology, 2000, MP-1-2, Dana Point, May 2000. Takashi Ohira et al., "Proposal of Adaptive Beam Forming by Microwave Signal Processing and Electronically Controlled Waveguide (ESPAR) Antenna", IEICE Technical Report, AP99-61 / SAT99-61, pp. 139-157. 9-14, July 1999. K. Gyoda et al., "Design of electronically steerable passive array radiator (ESPAR) antennas", 2000 IEEE AP-S International Symposium, 69P.7, Salt Lake City, July 2000. K. Shinjo et al., "Hamiltonian systems with many degrees of freedom: asymmetric motion and intensity of motion in phase space", Physical Review E, Vol. 54, pp.4685-4700, November 1996. K. Shinjo et al., "A strategy of designing routing algorithms based on ideal routings", International Journal of Modern Physics C, Vol. 10, No. 1, pp. 63-94, February 1999.

  However, it takes a lot of time to find the optimum combination of reactance values by repeating the calculation. The number of calculations is determined by the size of the range that can take one reactance value and the number of reactance elements, and if all combinations are examined, it is proportional to the size of the range raised to the power of the number of elements. As a method for speeding up the search for an optimal solution, a random method such as the Monte Carlo method is effective (for example, see Non-Patent Document 3). However, a large amount of time is still required to obtain an optimal reactance value. However, there is a problem in that a faster method is desired for investigating ESPAR antennas having various numbers of elements.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide an array antenna control device and a control method capable of calculating an optimum reactance value of an ESPAR antenna at a higher speed than in the related art.

An array antenna control device according to the present invention includes a radiating element to which a radio signal is fed, at least one non-exciting element that is provided at a predetermined distance from the radiating element and is not supplied with a radio signal, An array antenna control device, comprising: an array antenna including a variable reactance element connected to an excitation element, and changing a reactance value of the variable reactance element to change a directional characteristic of the array antenna.
Based on the azimuth indicating the direction in which the desired wireless input signal arrives, the reactance value of the variable reactance element is calculated by using a predetermined high-dimensional algorithm of motion as a function of the azimuth and the gain of the array antenna. And a calculating means for repeatedly calculating so as to minimize the evaluation function based on.

  Preferably, the control device for the array antenna further includes control means for controlling the reactance value of the variable reactance element calculated by the calculation means to be set in the variable reactance element. .

  Further, in the array antenna control device, preferably, the variable reactance element is a variable capacitance diode, and the capacitance of the variable capacitance diode is changed by changing a reverse bias voltage applied to the variable capacitance diode. And changing the directional characteristics of the array antenna.

  Still further, in the array antenna control device, preferably, a plurality of the non-exciting elements are provided, and the plurality of non-exciting elements are arranged at a circular position centered on the radiating element. And

An array antenna control method according to the present invention includes a radiating element to which a radio signal is supplied, at least one non-exciting element provided at a predetermined distance from the radiating element and not supplied with a radio signal, An array antenna comprising a variable reactance element connected to an excitation element, and a method for controlling an array antenna that changes a directional characteristic of the array antenna by changing a reactance value of the variable reactance element,
Based on the azimuth indicating the direction in which the desired wireless input signal arrives, the reactance value of the variable reactance element is calculated by using a predetermined high-dimensional algorithm of motion as a function of the azimuth and the gain of the array antenna. Characterized by including a step of repeatedly performing an operation so as to minimize the evaluation function based on.

  Preferably, the method of controlling the array antenna further includes a step of controlling the calculated reactance value of the variable reactance element to be set in the variable reactance element.

  As described above in detail, according to the present invention, in the conventional ESPAR antenna, based on the azimuth indicating the direction in which the desired wireless input signal arrives, the variable reactance is calculated by using a predetermined high-dimensional algorithm of motion. The reactance value of the element is a function of the azimuth angle and is repeatedly calculated so that the evaluation function based on the gain of the array antenna is minimized, so that the number of calculations is smaller than the conventional Monte Carlo method. Therefore, the optimum reactance value can be calculated very quickly and easily.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, first, the configuration of the array antenna used in the control device will be described, and then the configuration of the control device will be described.

<First embodiment>
FIG. 1 is a perspective view showing a configuration of an array antenna according to a first embodiment of the present invention, FIG. 2 is a schematic diagram showing a configuration of a feeding antenna element A0 of FIG. 1, and FIG. It is a schematic diagram which shows the structure of the parasitic variable reactance elements A1 to A4.

In the present embodiment, as shown in FIG. 1 is a monopole element, respectively, a feeding antenna element A0, 4 present parasitic variable-reactance elements A1 to A4 and the respective, the length L ₀ of the elements A0 each electrically insulated from the ground conductor 11 composed of a conductive plate having a length L _{i (i} = 1,2,3,4) sufficiently large size relative to the elements A1 to A4, and the feed antenna element A0 The passive variable reactance elements A1 to A4 are provided at the same 90-degree intervals from each other, for example, at a circular position having a radius d = λ / 4 centered at.

2, the feed antenna element A0 is provided with a radiating element 6 of electrically isolated cylindrical shape and the ground conductor 11 has a predetermined longitudinal length L ₀ of the example lambda / 4, radios ( The center conductor 21 of the power supply coaxial cable 20 for transmitting a wireless signal fed from the power supply (not shown) is connected to one end of the radiating element 6, and the outer conductor 22 is connected to the ground conductor 11. As a result, a wireless signal is fed from the wireless device to the feeding antenna element A0 via the coaxial cable 20, and emitted.

3, each of the parasitic variable reactance elements A1 to A4 has a predetermined length L _i (i = 1, 2, 3, 4) of, for example, λ / 4, and is electrically connected to the ground conductor 11. It has a similar structure including a columnar non-exciting element 7 which is electrically insulated, and a variable reactance element 23 having a reactance value X _i (i = 1, 2, 3, 4). Here, one end of the non-excitation element 7 is grounded at a high frequency to the ground conductor 11 via the variable reactance element 23. For example, assuming that the longitudinal lengths of the radiating element 6 and the non-exciting element 7 are substantially the same, for example, when the variable reactance element 23 has an inductance (L property), the variable reactance element 23 It becomes an extension coil, and the electrical length of the non-feeding variable reactance elements A1 to A4 becomes longer than that of the feeding antenna element A0, and works as a reflector. On the other hand, for example, when the variable reactance element 23 has a capacitance property (C property), the variable reactance element 23 becomes a shortening capacitor, and the electrical length of the parasitic variable reactance elements A1 to A4 is shorter than that of the feed antenna element A0. Work as a director.

  Therefore, in the array antenna of FIG. 1, by changing the reactance value of the variable reactance elements connected to the parasitic variable reactance elements A1 to A4, it is possible to change the overall planar directivity characteristics of the array antenna.

  FIG. 4 is a cross-sectional view showing a detailed configuration of the array antenna of FIG. 1. In the preferred embodiment of FIG. 4, a variable capacitance diode D is used as the variable reactance element 23.

  In FIG. 4, a ground conductor 11 is formed on the upper surface of a dielectric substrate 10 such as a polycarbonate, and the radiating element 6 penetrates the dielectric substrate 10 in the thickness direction while being electrically insulated from the ground conductor 11. It is supported, and wireless signals are supplied from a wireless device (not shown). The parasitic element 7 is supported while penetrating the dielectric substrate 10 in the thickness direction while being electrically insulated from the ground conductor 11. Here, one end of the non-excitation element 7 is grounded at high frequency to the ground conductor 11 via the variable capacitance diode D and the through-hole conductor 12 which is formed by filling and penetrating the dielectric substrate 10 in the thickness direction. At the same time, it is connected to the terminal T via the resistor R. The terminal T is grounded at a high frequency to the ground conductor 11 via a high-frequency bypass capacitor C and a through-hole conductor 13 which is formed by filling and penetrating the dielectric substrate 10 in the thickness direction.

  The terminal T is connected to a variable voltage DC power supply 30 which is voltage-controlled by a control device (not shown) of the array antenna, thereby changing the reverse bias voltage applied to the variable capacitance diode D, thereby The capacitance value of the capacitance diode D is changed. As a result, the electrical length of the parasitic variable reactance element A1 having the parasitic element 7 can be changed as compared with the feed antenna element A0, and the planar directivity characteristics of the array antenna can be changed. Further, the parasitic variable reactance elements A2 to A4 having the other parasitic elements 7 are similarly configured and have the same operation. The array antenna configured as described above can be called an ESPAR antenna.

  As described above, the array antenna according to the first embodiment has a very simple structure. For example, if the variable capacitance diode D is used, an array antenna capable of electronically controlling the directivity with a DC voltage can be obtained. realizable. The array antenna can be easily mounted on an electronic device such as a notebook computer or a PDA as an antenna for a mobile communication terminal, for example. The variable reactance elements A1 to A4 function effectively as a director or a reflector, and the control of the directivity is extremely easy.

<Second embodiment>
FIG. 5 is a perspective view showing a configuration of an array antenna according to a second embodiment of the present invention. The array antenna of this embodiment is obtained by replacing the monopole in the array antenna of FIG. 1 with a dipole. FIGS. 6 and 7 show analytical models of the array antenna of FIG. Here, FIG. 6 is a perspective view of the analysis model, and FIG. 7 is a plan view thereof.

  In FIG. 5, a feeding antenna element AA0 provided at the center of the array antenna includes a pair of radiating elements 6a and 6b spaced at a predetermined distance from each other and arranged on a straight line with each other. Opposite ends of 6a and 6b are connected to terminals T11 and T12, respectively. Here, the terminals T11 and T12 are connected to a wireless device (not shown) via a balanced transmission cable, and a wireless signal is supplied from the wireless device to the feeding antenna element AA0.

  Each of the parasitic variable reactance elements AA1 to AA4 provided at a predetermined angular interval from each other at a circular position around the feeding antenna element AA0 is spaced apart from each other by a predetermined distance and arranged on a straight line with each other. One end of each of the non-exciting elements 7a and 7b is connected via a variable capacitance diode D1, and one end of the variable capacitance diode D1 is connected to a terminal T1 via a resistor R1. The other end of the variable capacitance diode D1 is connected to a terminal T2 via a resistor R2. Here, a high-frequency bypass capacitor C1 is connected between the terminals T1 and T2. A variable voltage DC power supply (not shown) for applying a reverse bias voltage to the variable capacitance diode D1 is connected to the terminals T1 and T2, as in the first embodiment of FIG. .

  The capacitance value of the variable capacitance diode D is changed by changing the reverse bias voltage applied to the variable capacitance diode D1 of each of the parasitic variable reactance elements AA1 to AA4 by the variable voltage DC power supply. This makes it possible to change the electrical length of each of the parasitic variable reactance elements AA1 to AA4 including the parasitic elements 7a and 7b as compared with the feed antenna element AA0, thereby changing the planar directivity characteristics of the array antenna. it can.

  As described above, the array antenna according to the second embodiment has a very simple structure. For example, if the variable capacitance diode D1 is used, an array antenna whose directional characteristics can be electronically controlled with a DC voltage is realized. it can. The array antenna can be easily mounted on an electronic device such as a notebook computer or a PDA as an antenna for a mobile communication terminal, for example. The variable reactance elements AA1 to AA4 function effectively as a director or a reflector, and the control of the directivity is extremely easy.

<Modification>
In the above embodiments, the array antenna for transmission is described. However, since the device is a reversible circuit that does not include a non-reciprocal circuit, it can be used for reception.

  In the above embodiment, the four parasitic variable reactance elements A1 to A4 or AA1 to AA4 are used. Can be. Note that by increasing the number of parasitic variable reactance elements A1 to A4 or AA1 to AA4, it is possible to finely control the beam directivity and the beam direction. For example, the beam width of the main beam can be narrowed and sharpened. Can also be controlled.

  In addition, the layout configuration of the parasitic variable reactance elements A1 to A4 or AA1 to AA4 is not limited to the above-described embodiment, and may be any distance from the feeding antenna element A0 by a predetermined distance. That is, the distance d to each of the parasitic variable reactance elements A1 to A4 or AA1 to AA4 may not be constant.

  Further, the variable reactance element 23 is not limited to the variable capacitance diodes D and D1, but may be any element that can control the reactance value. Since the variable capacitance diodes D and D1 are generally capacitive circuit elements, the reactance value is always a negative value. The reactance value of the variable reactance element 23 may take a value ranging from a positive value to a negative value. For this purpose, for example, a fixed inductor is inserted in series with the variable capacitance diodes D and D1, or By increasing the length of the excitation element 7, the reactance value can be changed from a positive value to a negative value.

<Control device of the embodiment>
In the control device according to the present embodiment, the array antenna shown in FIGS. 6 and 7 according to the second embodiment was used as an analysis model, and the radiation pattern in the simulation was calculated using the moment method. Assuming that the ground conductor 11 is infinite for the sake of simplicity, each element A0 to A4 of the array antenna can be treated in the same manner as a dipole antenna in free space. The calculation parameters in this embodiment are determined as follows.
(A) The number n of the parasitic variable reactance elements A1 to A4 is four.
(B) The length of all the elements A0 to A4 is 2L _i (i = 0, 1, 2, 3, 4), and 2L _i = 0.463 wavelength.
(C) The distance d between the feeding antenna element A0 and the parasitic variable reactance elements A1 to A4 is １ ／ wavelength.
(D) The parameter for controlling the reactance value X _i of the parasitic variable reactance elements A1 to A4 is x _i (= 2X _i , i = 1, 2, 3, 4), and is changed within a range of ± 250Ω.

The control device according to the present embodiment gives an azimuth angle φ in a direction in which a desired radio wave arrives, and performs control to maximize a gain G (x ₁ , x ₂ ,..., X _n ; φ) in that direction. It is. This control is a control of a kind of optimization problem in which x _i is an unknown variable and the evaluation function V (x ₁ , x ₂ ,..., X _n ) which is a function of the reactance value and the azimuth and is based on the gain G is minimized. It is. The evaluation function here is represented by the following equation. Note that, in the specification, a numerical number of black brackets in which a mathematical expression is input as an image and a mathematical expression number of square brackets in which a mathematical expression is input are used in combination, and a series of numbers in the specification are used. It is assumed that the formula number is given to the last part of the formula by using the format of “formula (1)” and used.

[Equation 1]
V (x ₁ , x ₂ ,..., X _n ) = − G (x ₁ , x ₂ ,..., X _n ; φ) (1)

  In the present embodiment, a high-dimensional algorithm (for example, see Non-Patent Documents 4 and 5) is used to solve the above-described optimization problem. This high-dimensional algorithm solves optimization problems and is based on autonomous motion in Hamiltonian dynamics. Specifically, in this high-dimensional algorithm, the problem is replaced with the motion of the mass in n-dimensional space by associating the unknown variables with the coordinates of the mass and the evaluation function with the potential energy. Then solve the problem by tracking its movement. In the present embodiment, the Hamiltonian H of the mass point is given by the following equation.

Here, the second term on the right side of Equation (2) means kinetic energy expressed as a function of momentum p _i . Originally, this term has no relation to the variable to be optimized and the evaluation function, so that the term can be modified, and a new positive constant γ is introduced to improve the efficiency of the solution search. In a real system, γ = 1. If the Hamiltonian dynamics is analyzed in detail, the probability density that the mass point exists at the mass coordinate x _i , which is an unknown variable corresponding to the reactance value, is proportional to the following equation (for example, see Non-Patent Document 5).

  Here, E is the total energy. This means that a mass point exists with a high probability at a position with low potential energy when the following equation is satisfied.

  In other words, if this condition is satisfied, it is easy to find the optimal solution. The motion of the mass point is calculated using the following equation of motion.

In the calculation in the present embodiment, the initial values of the mass coordinates x _i and the momentum p _i are empirically given, and the positive constant γ is empirically set to 0.3. In the calculation by the high-dimensional algorithm by the controller 100 described later, the reactance is obtained by repeatedly changing the mass coordinates x _i and the momentum p _i with time t using the above equations (2), (5) and (6). The mass coordinates x _i corresponding to the values are sequentially calculated. The mass point is calculated so as to be totally reflected as shown below at the boundary of the reactance value (± 250Ω). Here, the time is t, and the increment is Δt.

(1) During the calculation of the time (t + Δt),
[Equation 2]
x _i (t + Δt)> maximum value Max (for example, + 250Ω) (7)
In the following equation, the result on the right side is substituted into the left side in the following equation.

[Equation 3]
x _i (t + Δt) = 2 · Max−x _i (t + Δt) (8)
[Equation 4]
x _i (t) = 2 · Max−x _i (t) (9)
[Equation 5]
p _i (t) = − p _i (t) (10)
[Equation 6]
p _i (t−Δt) = − p _i (t−Δt) (11)
[Equation 7]
_{(∂p i / ∂t) (t} ) = - (∂p i / ∂t) (t) (12)

(2) During the calculation of the time (t + Δt),
[Equation 8]
x _i (t + Δt) <minimum value Min (for example, −250Ω) (13)
In the following equation, the result on the right side is substituted into the left side in the following equation.

[Equation 9]
x _i (t + Δt) = 2 · Min−x _i (t + Δt) (14)
[Equation 10]
x _i (t) = 2 · Min−x _i (t) (15)
[Equation 11]
p _i (t) = − p _i (t) (16)
[Equation 12]
p _i (t−Δt) = − p _i (t−Δt) (17)
[Equation 13]
(∂p _i / ∂t) (t) = − (∂p _i / ∂t) (t) (18)

FIG. 8 is a block diagram showing a controller 100 for controlling the directional characteristics of the array antenna of the present embodiment and its peripheral circuits. 8, the controller 100 includes:
(A) a CPU 101 which is a digital computer for performing arithmetic control of the device;
(B) a ROM 102 storing at least a program including the control processing of the array antenna of FIG. 9 and data necessary for executing the program;
(C) a RAM 103 which is used as a working memory of the CPU 101 and temporarily stores data during the operation and the result of the operation;
(D) a keyboard interface 104 that is connected to the keyboard 111 and executes a predetermined signal conversion process on a signal from the keyboard 111 and outputs the signal to the CPU 101;
(E) a display interface 105 that is connected to the CRT display 112, executes a predetermined signal conversion process on the data calculated by the CPU 101, and outputs the data to the CRT display 112 for display;
(F) a printer interface 106 which is connected to the printer 113, executes predetermined signal conversion processing on the data calculated by the CPU 101, and outputs the data to the printer 113 for printing;
(G) Connected to the variable reactance 23 (FIG. 3) of the array antenna, executes a predetermined signal conversion process on the reactance value data calculated by the CPU 101, outputs the result to the variable reactance 23, and sets the value. A control interface 107;
These circuits 101 to 107 are connected via a bus 108. The input process from the keyboard 111 is executed by the CPU 101 as an interrupt process.

  In the above embodiment, the azimuth angle φ of the desired radio wave is input using the keyboard 111. However, the present invention is not limited to this, and the arrival angle of the desired wave is obtained by processing the received signal by a known method. May be calculated and used as input data of the controller 100.

FIG. 9 is a flowchart showing a control process of the array antenna executed by the controller 100 of FIG. In FIG. 9, first, it is determined whether or not the azimuth angle φ in the direction in which the desired radio wave arrives is determined in step S1, and the process of step S1 is repeated until the result becomes YES. Initialize to 1. Next, based on the azimuth angle φ input in step S3, a reactance value that minimizes the evaluation function V (x ₁ , x ₂ ,..., X _n ) of Expression (1) using the above-described high-dimensional algorithm. x ₁ , x ₂ ,..., x _n are calculated. Then, in step S4, it is determined whether or not the parameter m is equal to or more than a predetermined threshold value m ₀ (for example, 10,000) as an end condition. If NO, the parameter m is incremented by 1 in step S5. Then, the process of step S3 is repeated. In this repetitive processing, the operation of the high-dimensional algorithm is executed using the previous reactance value x _i and momentum p _i . On the other hand, it is determined that time is YES in step S4 is processing is ended, the calculated reactance x _1, x ₂ in step S6, ..., displaying each output x _n on the CRT display 112 and printer 113 And print. Furthermore, the calculated reactance x _1, x ₂ in step S7, ..., by controlling the variable reactance 23 such that x _n the process returns to step S1.

The present inventors have applied an arithmetic control process that applies a high-dimensional algorithm to the analysis models illustrated in FIGS. 6 and 7 according to the second embodiment, and an arithmetic control process using a conventional Monte Carlo method. The processing is simulated, and the results are shown below. In the figures referred to below, HA is an arithmetic control process using a high-dimensional algorithm, and MC is an arithmetic control process when the Monte Carlo method is used. In this simulation, the reactance value was updated 10,000 times for the desired azimuth angle from 0 ° to 45 ° in increments of 5 °, m ₀ = 10,000, and the optimum reactance value was obtained. It is sufficient to calculate for angles in this range due to the contrasting structure of the antenna.

FIGS. 10 to 13 are simulation results of the second embodiment using the high-dimensional algorithm, respectively. Mass points representing reactance values when the azimuth φ of the desired radio wave is 0, 15, 30, 45 (degrees) it is a graph showing the trajectory of the coordinates x _i, (a) is a graph showing the x ₁ -x ₃ characteristic when the, (b) is a graph showing the x ₂ -x ₄ properties. As is clear from FIGS. 10 to 13, it can be seen that the trajectory is well concentrated near the optimal solution.

  14 to 17 show the simulation results of the second embodiment using the high-dimensional algorithm and the simulation results by the Monte Carlo method, respectively, when the azimuth φ of the desired radio wave is 0, 15, 30, 45 (degrees). 6 is a graph showing a histogram of the gains of FIG. These figures show the frequency obtained by dividing the resulting gain by 0.2 dB, and also show, for comparison, histograms of the results obtained by the Monte Carlo method with the same number of calculations. From FIG. 14 to FIG. 17, it is apparent that the higher-dimensional algorithm is more concentrated in the higher gain region than the Monte Carlo method.

FIG. 18 is a graph showing a simulation result of the second embodiment using the high-dimensional algorithm and a simulation result by the Monte Carlo method, and is a graph showing an optimum reactance value that gives the maximum gain with respect to the azimuth φ of the desired radio wave. FIG. 18 shows the optimum value of the reactance value x _i that gives the maximum gain, obtained by performing the calculation 10,000 times and the Monte Carlo method 50,000 times for the high-dimensional algorithm. Similar results have been obtained.

  FIG. 19 shows a simulation result of the second embodiment using the high-dimensional algorithm and a simulation result by the Monte Carlo method, and is a graph showing the maximum gain with respect to the azimuth angle φ of the desired radio wave. As is apparent from FIG. 19, the gain value of 9.1 dBi ± 0.5 dB is almost the same for all angles in the high-dimensional algorithm although the number of calculations is 1/5 of that of the Monte Carlo method. I have.

  FIG. 20 is a directional characteristic diagram showing a radiation pattern when a reactance value is optimized so as to obtain a maximum gain at an azimuth angle φ of a desired radio wave, which is a simulation result of the second embodiment using a high-dimensional algorithm. (A) is a directional characteristic diagram when the azimuth angle φ = 0 (degree), (b) is a directional characteristic diagram when the azimuth angle = 15 (degree), and (c) is an azimuth angle. It is a directional pattern when φ = 30 (degrees), and (d) is a directional pattern when azimuth φ = 45 (degrees). Here, it should be noted that the fact that the gain at the specified angle is the maximum does not necessarily correspond to the fact that the radiation pattern has a peak at that angle.

  As described above, this embodiment is the first to introduce a high-dimensional algorithm for the optimization problem in the ESPAR antenna. An example is shown in which the problem of finding the optimum reactance of the parasitic element for maximizing the gain in the specified direction is solved for a five-element ESPAR antenna. Compared to the conventional Monte Carlo method, the algorithm according to the present embodiment was able to find the optimum reactance value with about 1/5 the number of calculations. The obtained directivity gain is 9.1 dBi ± 0.5 dB for all azimuth angles.

  In general, a high-dimensional algorithm is effective for a problem having many unknown variables, and thus can be applied to optimization of an ESPAR antenna having a complicated structure with a larger number of elements.

FIG. 1 is a perspective view illustrating a configuration of an array antenna according to a first embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a configuration of a feeding antenna element A0 in FIG. 1. FIG. 2 is a schematic diagram illustrating a configuration of a parasitic variable reactance element A1 to A4 in FIG. 1. FIG. 2 is a sectional view showing a detailed configuration of the array antenna of FIG. 1. It is a perspective view showing the composition of the array antenna which is a 2nd embodiment concerning the present invention. It is a perspective view showing an analysis model of an array antenna of a 2nd embodiment. FIG. 7 is a plan view showing a planar arrangement of the array antenna of FIG. 6. FIG. 3 is a block diagram illustrating a controller 100 that controls the directional characteristics of the array antenna according to the present embodiment and peripheral circuits thereof. 9 is a flowchart illustrating an array antenna field control process executed by the controller 100 of FIG. 8. A second simulation of the embodiment results with high-dimensional algorithm is a graph showing the trajectory of the reactance value when the desired radio wave azimuth angle phi = 0 (degrees), (a) it is x ₁ at that time is a graph showing the -x ₃ properties, (b) is a graph showing the x ₂ -x ₄ properties. The result of a simulation of the second embodiment using the high-dimensional algorithm is a graph showing the trajectory of the reactance value when the desired radio wave azimuth angle phi = 15 (degrees), (a) it is x ₁ at that time is a graph showing the -x ₃ properties, (b) is a graph showing the x ₂ -x ₄ properties. The result of a simulation of the second embodiment using the high-dimensional algorithm is a graph showing the trajectory of the reactance value when the desired radio wave azimuth angle phi = 30 (degrees), (a) it is x ₁ at that time is a graph showing the -x ₃ properties, (b) is a graph showing the x ₂ -x ₄ properties. The result of a simulation of the second embodiment using the high-dimensional algorithm is a graph showing the trajectory of the reactance value when the desired radio wave azimuth angle phi = 45 (degrees), (a) it is x ₁ at that time is a graph showing the -x ₃ properties, (b) is a graph showing the x ₂ -x ₄ properties. 7 is a graph showing a simulation result of the second embodiment using a high-dimensional algorithm and a simulation result by the Monte Carlo method, and showing a histogram of gain when the azimuth φ of a desired radio wave is 0 (degrees). It is a simulation result of a 2nd embodiment using a high-dimensional algorithm, and a simulation result by the Monte Carlo method, and is a graph showing a histogram of a gain at the time of azimuth φ = 15 (degrees) of a desired electric wave. FIG. 9 is a graph showing a simulation result of the second embodiment using a high-dimensional algorithm and a simulation result by a Monte Carlo method, and showing a histogram of gain when the azimuth φ of a desired radio wave is 30 (degrees). 9 is a graph showing a simulation result of the second embodiment using the high-dimensional algorithm and a simulation result by the Monte Carlo method, and showing a histogram of a gain when the azimuth φ of the desired radio wave is 45 (degrees). 9 is a graph showing a simulation result of the second embodiment using a high-dimensional algorithm and a simulation result by a Monte Carlo method, and is a graph showing an optimum reactance value that gives a maximum gain with respect to an azimuth φ of a desired radio wave. 9 is a graph showing a simulation result of the second embodiment using a high-dimensional algorithm and a simulation result by a Monte Carlo method, and is a graph showing a maximum gain with respect to an azimuth angle φ of a desired radio wave. FIG. 9 is a simulation result of the second embodiment using a high-dimensional algorithm, and is a directional pattern diagram showing a radiation pattern when a reactance value is optimized so as to obtain a maximum gain at an azimuth angle φ of a desired radio wave. ) Is a directional characteristic diagram when the azimuth angle φ = 0 (degree), (b) is a directional characteristic diagram when the azimuth angle φ = 15 (degree), and (c) is an azimuth angle φ = 30 (degree). (D) is a directional characteristic diagram, and (d) is a directional characteristic diagram at an azimuth angle φ = 45 (degree).

Explanation of reference numerals

A0, AA0 ... feeding antenna element,
A1 to A4, AA1 to AA4 ... parasitic variable reactance elements,
C, C1 ... capacitor,
D, D1 ... variable capacitance diode,
R, R1, R2 ... resistance,
T, T1, T2 ... terminals,
6,6a, 6b ... radiating element,
7, 7a, 7b ... non-excitation element,
10: dielectric substrate,
11 ground conductor
12, 13 ... through-hole conductor,
20: Coaxial cable for power supply,
21 ... Center conductor,
22 ... outer conductor,
23 ... variable reactance element,
30 ... Variable voltage DC power supply,
100 ... controller,
101 ... CPU,
102 ... ROM,
103 ... RAM,
104 ... keyboard interface,
105 ... display interface,
106 ... Printer interface,
107 ... Control interface,
108 ... bus,
111 ... keyboard,
112 ... CRT display,
113 ... Printer.

Claims (6)

A radiating element to which a radio signal is fed, at least one parasitic element provided at a predetermined distance from the radiating element and not supplied with a radio signal, and a variable reactance element connected to the parasitic element. An array antenna control device comprising an array antenna comprising: changing a reactance value of the variable reactance element to change a directional characteristic of the array antenna;
Based on the azimuth indicating the direction in which the desired wireless input signal arrives, the reactance value of the variable reactance element is calculated by using a predetermined high-dimensional algorithm of motion as a function of the azimuth and the gain of the array antenna. A control device for an array antenna, comprising: a calculating means for repeatedly calculating so as to minimize an evaluation function based on. The control device for an array antenna according to claim 1,
A control device for an array antenna, further comprising control means for controlling the reactance value of the variable reactance element calculated by the calculation means to be set in the variable reactance element. The control device for an array antenna according to claim 1 or 2,
The variable reactance element is a variable capacitance diode,
A control device for an array antenna, wherein the directivity characteristic of the array antenna is changed by changing a capacitance of the variable capacitance diode by changing a reverse bias voltage applied to the variable capacitance diode. The control device for an array antenna according to any one of claims 1 to 3,
A control device for an array antenna, comprising: a plurality of said non-excitation elements; wherein said plurality of non-excitation elements are arranged at a circular position centered on said radiation element. A radiating element to which a radio signal is fed, at least one parasitic element provided at a predetermined distance from the radiating element and not supplied with a radio signal, and a variable reactance element connected to the parasitic element. An array antenna control method comprising: an array antenna comprising: changing a reactance value of the variable reactance element to change a directional characteristic of the array antenna;
Based on the azimuth indicating the direction in which the desired wireless input signal arrives, the reactance value of the variable reactance element is calculated by using a predetermined high-dimensional algorithm of motion as a function of the azimuth and the gain of the array antenna. A method for controlling an array antenna, comprising a step of repeatedly performing an operation so that an evaluation function based on the minimum is obtained. The method for controlling an array antenna according to claim 5,
And controlling the calculated reactance value of the variable reactance element so as to set the variable reactance element to the variable reactance element.

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