Phased array antenna evaluation method

Abstract

This phased array antenna evaluation method evaluates a phased array antenna comprising a plurality of antennas for carrying out transmission or reception of a first polarization and a second polarization, the oscillation directions of which are orthogonal to one another. This method uses a reference antenna that is disposed opposite to the phased array antenna and carries out transmission or reception of radio waves oscillating in a reference direction. Evaluation of the first polarization and the second polarization is carried out simultaneously in a state in which: a first direction in which the first polarization oscillates is not parallel to the reference direction when viewed from an opposition direction in which the phased array antenna and the reference antenna are opposite one another; and a second direction in which the second polarization oscillates is not parallel to the reference direction when viewed from the opposition direction.

Description

[Technical Field]

[0001] The present invention relates to a phased array antenna evaluation method. This application claims priority based on Japanese Patent Application No. 2023-020631, filed on February 14, 2023, the contents of which are incorporated herein by reference. [Background technology]

[0002] Conventionally, there is known an evaluation device that evaluates (inspects) a phased array antenna having multiple antennas (see, for example, Patent Document 1). The evaluation device of Patent Document 1 includes multiple reference antennas arranged to face the phased array antenna to be evaluated. Each reference antenna has a single reference direction. The reference antenna can transmit or receive radio waves oscillating in the reference direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2010-124360 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, each of the multiple antennas included in a phased array antenna may transmit and receive H polarization and V polarization, whose vibration directions are orthogonal to each other. In such cases, from the viewpoint of evaluation efficiency, it is preferable to simultaneously evaluate the H polarization and the V polarization. Hereinafter, the direction in which the H polarization vibrates will be referred to as the H polarization direction, and the direction in which the V polarization vibrates will be referred to as the V polarization direction.

[0005] In order to simultaneously evaluate the H polarization and the V polarization in the evaluation device of Patent Document 1, one of the multiple reference antennas (hereinafter referred to as the first reference antenna) and another of the multiple reference antennas (hereinafter referred to as the second reference antenna) can be arranged as follows: That is, the first reference antenna and the second reference antenna can be arranged so that the reference direction of the first reference antenna coincides with the H polarization direction, and the reference direction of the second reference antenna coincides with the V polarization direction. With this arrangement, the H polarization can be evaluated using the first reference antenna, and the V polarization can be evaluated using the second reference antenna at the same time.

[0006] In order for the two reference antennas to properly transmit and receive radio waves, the two reference antennas must be placed at different positions parallel to the phased array antenna, which creates a problem in that both the first and second reference antennas cannot be positioned opposite the center of the phased array antenna.

[0007] The present invention has been made in consideration of the above circumstances, and has an object to provide a phased array antenna evaluation method that can simultaneously evaluate two mutually orthogonal polarized waves using a single reference antenna. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, a phased array antenna evaluation method according to a first aspect of the present invention is a phased array antenna evaluation method for evaluating a phased array antenna having a plurality of antennas that transmit or receive first polarized waves and second polarized waves whose vibration directions are orthogonal to each other, using a reference antenna that is arranged opposite the phased array antenna and transmits or receives radio waves that vibrate in a reference direction, and simultaneously evaluating the first polarized wave and the second polarized wave in a state in which a first direction in which the first polarized wave vibrates is not parallel to the reference direction when viewed from the opposing direction in which the phased array antenna and the reference antenna face each other, and a second direction in which the second polarized wave vibrates is not parallel to the reference direction when viewed from the opposing direction.

[0009] According to the first aspect of the present invention, since the reference direction is not parallel to either the first direction or the second direction, the first polarization and the second polarization can be simultaneously evaluated by the reference antenna. Also, this method can be realized by a single reference antenna.

[0010] According to a second aspect of the present invention, in the phased array antenna evaluation method of the first aspect, the relative angle between the first direction and the reference direction when viewed from the opposing direction is not less than 35° and not more than 55°.

[0011] According to a third aspect of the present invention, in the phased array antenna evaluation method of the first or second aspect, the center of the phased array antenna and the center of the reference antenna coincide with each other when viewed from the opposing direction.

[0012] Furthermore, a fourth aspect of the present invention relates to a phased array antenna evaluation method according to any one of the first to third aspects, wherein the first polarized wave having a first frequency and the second polarized wave having a second frequency different from the first frequency are simultaneously transmitted from the phased array antenna, and the first polarized wave and the second polarized wave are simultaneously received by the reference antenna.

[0013] Furthermore, a fifth aspect of the present invention is a phased array antenna evaluation method according to any one of the first to third aspects, in which a first radio wave having a first frequency is transmitted from the reference antenna, and the first radio wave is received by the phased array antenna.

[0014] Furthermore, a sixth aspect of the present invention relates to the phased array antenna evaluation method of the fifth aspect, in which the first radio wave and a second radio wave having a second frequency different from the first frequency are transmitted from the reference antenna, and the first radio wave and the second radio wave are simultaneously received by the phased array antenna. [Effects of the Invention]

[0015] According to the above aspect of the present invention, it is possible to provide a phased array antenna evaluation method that can simultaneously evaluate two mutually orthogonal polarized waves using a single reference antenna. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 2 is a diagram illustrating the positional relationship between a phased array antenna and a reference antenna according to an embodiment of the present invention. [Figure 2A] FIG. 2 is a diagram showing a first example of a specific method for simultaneously evaluating H polarization and V polarization using a phased array antenna and a reference antenna positioned as shown in FIG. [Figure 2B] FIG. 2 is a diagram showing a second example of a specific method for simultaneously evaluating H polarization and V polarization using a phased array antenna and a reference antenna positioned as shown in FIG. [Figure 2C] FIG. 10 is a diagram showing a third example of a specific method for simultaneously evaluating H polarization and V polarization using a phased array antenna and a reference antenna positioned as shown in FIG. [Figure 3] FIG. 10 is a diagram showing a modified example of the present invention. [Figure 4] 10 is a graph showing the measurement results obtained by a spectrum analyzer for each of the cases of (a) α=0° and (b) α=45°. [Figure 5]10 is a graph showing the effective radiated power of H polarization and V polarization for each of a plurality of antennas included in a phased array antenna. [Figure 6] 10 is a graph showing the beam pattern of a phased array antenna when (a) the beam direction angle θ is −60°, (b) the beam direction angle θ is −30°, (c) the beam direction angle θ is 0°, (d) the beam direction angle θ is 30°, and (e) the beam direction angle θ is 60°. [Figure 7] 10 is a graph showing beam patterns of a tiled phased array antenna for each of the cases where (a) the beam direction angle θ is −60°, (b) the beam direction angle θ is −30°, (c) the beam direction angle θ is 0°, (d) the beam direction angle θ is 30°, and (e) the beam direction angle θ is 60°. [Figure 8A] 10 is a graph showing the change in intensity of H-polarized waves when the value of α is changed in the range of −90°≦α≦90°. [Figure 8B] 8B is a graph obtained by extracting the range of −55°≦α≦−35° from the graph of FIG. 8A. [Figure 8C] This is a graph obtained by extracting the range of 35°≦α≦55° from the graph of FIG. 8A. DETAILED DESCRIPTION OF THE INVENTION

[0017] A phased array antenna evaluation method according to an embodiment of the present invention will be described below with reference to the drawings.

[0018] As shown in Fig. 1, an evaluation system (phased array antenna evaluation system) 1 according to this embodiment includes a phased array antenna 10 and a reference antenna 20. The phased array antenna 10 is mounted on a substrate B. The evaluation system 1 is a system that evaluates the phased array antenna 10 using the reference antenna 20.

[0019] The phased array antenna 10 has multiple antennas 11. Each antenna 11 transmits and receives first and second polarized waves whose vibration directions are orthogonal to each other. Hereinafter, the direction in which the first polarized wave oscillates will be referred to as the first direction, and the direction in which the second polarized wave oscillates will be referred to as the second direction. One of the first and second polarized waves is H polarization, and the other of the first and second polarized waves is V polarization. Hereinafter, the first polarization will be described as H polarization and the second polarization as V polarization. The first direction will be referred to as the H polarization direction (H pol. (H polarization)) and is represented by the symbol H in the drawings. The second direction will be referred to as the V polarization direction (V pol. (V polarization)) and is represented by the symbol V in the drawings.

[0020] The multiple antennas 11 are arranged two-dimensionally in the V polarization direction and the H polarization direction. In the illustrated example, eight antennas 11 are arranged in each of the V polarization direction and the H polarization direction. This results in a total of 64 antennas 11 arranged two-dimensionally.

[0021] The reference antenna 20 transmits and receives radio waves to and from the phased array antenna 10. The reference antenna 20 has a reference direction (electric field direction) E. The reference direction E is a single direction determined by the design of the reference antenna 20. The reference antenna 20 can transmit or receive radio waves that oscillate in the reference direction E.

[0022] A horn antenna, for example, can be used as the reference antenna 20. In the illustrated example, a rectangular horn antenna having a pair of long sides 20a and a pair of short sides 20b in a plan view is used as the reference antenna 20. In this reference antenna 20, the reference direction E is, for example, a direction parallel to the short sides 20b. However, the reference direction E may also be inclined with respect to the short sides 20b.

[0023] The reference antenna 20 is disposed so as to face the phased array antenna 10 in a facing direction orthogonal to both the V polarization direction and the H polarization direction. In other words, the reference antenna 20 is disposed so as to overlap with the phased array antenna 10 in a plan view seen from the facing direction. In particular, it is desirable that the phased array antenna 10 and the reference antenna 20 are disposed so that the center O1 of the phased array antenna 10 and the center O2 of the reference antenna 20 overlap in a plan view. Note that the "facing direction" is also a direction orthogonal to the in-plane direction of the substrate B on which the phased array antenna 10 is mounted (the in-plane direction of the phased array antenna 10).

[0024] In this embodiment, as shown in FIG. 1 , the reference antenna 20 is disposed at an angle with respect to the phased array antenna 10. That is, the phased array antenna 10 and the reference antenna 20 are disposed so that the H polarization direction and the reference direction E are non-parallel (the relative angle α is not 0°) and the V polarization direction and the reference direction E are non-parallel in a planar view. More specifically, the phased array antenna 10 and the reference antenna 20 are disposed so that the relative angle α between the H polarization direction and the reference direction E is approximately 45° in a planar view. The specific range of the relative angle α will be described later. The phrase "the relative angle α is 45°" includes both the first and second cases described below. In the first case, the angle measured with the counterclockwise direction from the H polarization direction as the positive direction in a planar view is 45° (the orientation shown in FIG. 1 ). In the second case, the angle measured with the clockwise direction from the H polarization direction as the positive direction in a planar view is 45° (the opposite orientation to the orientation shown in FIG. 1 ). In the illustrated example, the relative angle between the H polarization direction and the short side 20b of the reference antenna 20 is about 45°.

[0025] By setting the relative angle α between the phased array antenna 10 and the reference antenna 20 to approximately 45°, the angle between the H polarization direction and the reference direction E and the angle between the V polarization direction and the reference direction E become approximately the same. As a result, the intensity of the radio waves received by the reference antenna 20 becomes approximately the same when the phased array antenna 10 transmits H polarization and when the reference antenna 20 transmits V polarization. Furthermore, when radio waves oscillating in the reference direction E are transmitted from the reference antenna 20 to the phased array antenna 10, the radio waves are received with approximately the same intensity by the phased array antenna 10 due to the sensitivity in a direction parallel to the H polarization and the sensitivity in a direction parallel to the V polarization. In this way, by setting the relative angle α between the phased array antenna 10 and the reference antenna 20 to approximately 45°, H polarization and V polarization can be transmitted and received between the phased array antenna 10 and the reference antenna 20 with approximately the same intensity. This allows the single reference antenna 20 to simultaneously evaluate the H polarization and the V polarization, which are orthogonal to each other.

[0026] Hereinafter, a specific example of an evaluation system 1 and an evaluation method for simultaneously evaluating H polarization and V polarization using a single reference antenna 20 will be described with reference to FIGS. 2A to 2C.

[0027] 2A includes, in addition to the phased array antenna 10 and the reference antenna 20, a signal generator (SG) 41, two vector signal generators (VSG) 42 and 43, and a measuring instrument 51. Hereinafter, the two vector signal generators 42 and 43 will be referred to as a first vector signal generator 42 and a second vector signal generator 43, respectively.

[0028] The signal generator 41 and each of the vector signal generators 42 and 43 are electrically connected to the phased array antenna 10. The signal generator 41 outputs an LO signal to the phased array antenna 10. The first vector signal generator 42 outputs an IF signal corresponding to H polarization to the phased array antenna 10. The second vector signal generator 43 outputs an IF signal corresponding to V polarization to the phased array antenna 10. Here, the frequency of the IF signal output by the first vector signal generator 42 and the frequency of the IF signal output by the second vector signal generator 43 are different from each other.

[0029] The phased array antenna 10 frequency-converts (up-converts) the IF signal received from the first vector signal generator 42 using the LO signal received from the signal generator 41. As a result, the phased array antenna 10 generates an H polarized wave. Furthermore, the phased array antenna 10 frequency-converts (up-converts) the IF signal received from the second vector signal generator 43 using the LO signal received from the signal generator 41. As a result, the phased array antenna 10 generates a V polarized wave. Then, the phased array antenna 10 simultaneously transmits the generated H polarized wave and V polarized wave to the reference antenna 20.

[0030] The reference antenna 20 simultaneously receives the H polarized waves and V polarized waves transmitted from the phased array antenna 10. Because the relative angle α between the phased array antenna 10 and the reference antenna 20 is approximately 45°, the reference antenna 20 receives the H polarized waves and V polarized waves with approximately the same intensity. The reference antenna 20 outputs the received H polarized waves and V polarized waves to a measuring instrument 51 electrically connected to the reference antenna 20. The measuring instrument 51 is, for example, a spectrum analyzer (SA) or the like that measures the intensity of the radio waves received by the reference antenna 20 for each frequency.

[0031] Here, the IF signals output by signal generators 42 and 43 have different frequencies, and therefore the frequency (first frequency) of the H polarization transmitted by phased array antenna 10 and the frequency (second frequency) of the V polarization transmitted by phased array antenna 10 are different. Therefore, measuring instrument 51 can distinguish between the H polarization and the V polarization based on the difference in frequency. In this way, evaluation system 1A shown in FIG. 2A can simultaneously evaluate the H polarization and the V polarization when phased array antenna 10 transmits radio waves.

[0032] Evaluation system 1B shown in Fig. 2B has a configuration obtained by partially modifying evaluation system 1A shown in Fig. 2A. That is, evaluation system 1B has a configuration in which vector signal generators 42 and 43 of evaluation system 1A are replaced with two measuring instruments 44 and 45, and measuring instrument 51 is replaced with vector signal generator 52. Hereinafter, the two measuring instruments 44 and 45 will be referred to as first measuring instrument 44 and second measuring instrument 45, respectively.

[0033] The vector signal generator 52 is electrically connected to the reference antenna 20. The vector signal generator 52 outputs an RF signal having a single frequency (first frequency) to the reference antenna 20. Based on the RF signal received from the vector signal generator 52, the reference antenna 20 transmits radio waves oscillating in the reference direction E to the phased array antenna 10.

[0034] The phased array antenna 10 receives the radio waves transmitted from the reference antenna 20 with sensitivity in a direction parallel to the H polarization and sensitivity in a direction parallel to the V polarization. In other words, of the radio waves oscillating in the reference direction E, the H polarization direction component is received as H polarization and the V polarization direction component is received as V polarization. Since the relative angle α between the phased array antenna 10 and the reference antenna 20 is around 45°, the phased array antenna 10 receives the H polarization and the V polarization with approximately the same intensity.

[0035] The phased array antenna 10 frequency-converts (down-converts) the RF signal using the LO signal received from the signal generator 41, converting it into an IF signal. The phased array antenna 10 can perform this frequency conversion independently for each of the H polarization and the V polarization, and therefore outputs the IF signals for the H polarization and the V polarization to the first measuring instrument 44 and the second measuring instrument 45, respectively. That is, the IF signal for the H polarization is output to the first measuring instrument 44, and the IF signal for the V polarization is output to the second measuring instrument 45. The measuring instruments 44 and 45 are, for example, the above-mentioned spectrum analyzer or a power sensor (PS) that measures the intensity of the IF signal. With this configuration, the first measuring instrument 44 and the second measuring instrument 45 can independently evaluate the H polarization and the V polarization. As such, the evaluation system 1B shown in FIG. 2B can simultaneously evaluate the H polarization and the V polarization when the phased array antenna 10 receives radio waves.

[0036] The evaluation system 1C shown in Fig. 2C has a configuration obtained by partially modifying the evaluation system 1B shown in Fig. 2B. That is, the evaluation system 1C has a configuration in which the second measuring instrument 45 is removed from the evaluation system 1B and a vector signal generator 53 and two combiners 54 and 46 are added. Hereinafter, the two vector signal generators 52 and 53 will be referred to as the first vector signal generator 52 and the second vector signal generator 53, respectively. Furthermore, the two combiners 54 and 46 will be referred to as the first combiner 54 and the second combiner 46, respectively.

[0037] The first vector signal generator 52 outputs an RF signal having a single frequency (first frequency) to the first combiner 54. The second vector signal generator 53 outputs an RF signal having a single frequency (second frequency) different from the first frequency to the first combiner 54. The first combiner 54 combines the RF signal received from the first vector signal generator 52 and the RF signal received from the second vector signal generator 53, and outputs the combined wave to the reference antenna 20. The reference antenna 20 simultaneously transmits a first radio wave having the first frequency and a second radio wave having the second frequency to the phased array antenna 10 based on the combined RF signal.

[0038] The phased array antenna 10 receives the first and second radio waves from the reference antenna 20 with sensitivity in a direction parallel to the H polarization and sensitivity in a direction parallel to the V polarization. The phased array antenna 10 then frequency-converts (down-converts) the RF signal using the LO signal received from the signal generator 41, converting it into an IF signal. The phased array antenna 10 can perform this frequency conversion independently for the H polarization and the V polarization. Therefore, the phased array antenna 10 outputs an IF signal for the H polarization, having a frequency corresponding to the first frequency, from a first port P1 to a second combiner 46. The phased array antenna 10 then outputs an IF signal for the V polarization, having a frequency corresponding to the second frequency, from a second port P2 to the second combiner 46.

[0039] The second combiner 46 combines the H polarized wave having a frequency corresponding to the first frequency received from the first port P1 and the V polarized wave having a frequency corresponding to the second frequency received from the second port P2. The second combiner 46 outputs the combined wave to the measuring instrument 44. As with the above-described evaluation system 1B, this evaluation system 1C can simultaneously evaluate the H polarized wave and the V polarized wave when the phased array antenna 10 receives radio waves. Compared to evaluation system 1B, evaluation system 1C has the advantage of being able to reduce the number of measuring instruments and making it easier to miniaturize the entire evaluation system.

[0040] The evaluation system 1 described above is a system that evaluates a phased array antenna 10 using a reference antenna 20. However, as in the evaluation system 2 shown in FIG. 3, a phased array antenna group 30 may be evaluated using a reference antenna 20. The phased array antenna group 30 has a plurality of phased array antennas 10 (four in the illustrated example). The plurality of phased array antennas 10 are arranged (tiled) in the V polarization direction and the H polarization direction. In this case, it is desirable that the phased array antenna group 30 and the reference antenna 20 are arranged so that the center O3 of the phased array antenna group 30 and the center O2 of the reference antenna 20 overlap in a planar view. Note that the phased array antenna group 30 in the illustrated example can also be considered as a phased array antenna having 16 antennas 11 arranged in both the V polarization direction and the H polarization direction, for a total of 256 antennas 11. [Example]

[0041] The above embodiment will be described below using specific examples, but the present invention is not limited to the following examples.

[0042] Example 1 Using the evaluation system 1A shown in Fig. 2A, H polarized waves and V polarized waves were simultaneously transmitted from the phased array antenna 10, and both polarized waves were simultaneously evaluated. The specific conditions were as follows. Frequency of the LO signal output by the signal generator 41 (f1): 6.1 (GHz) Frequency (f2) of the IF signal output by the first vector signal generator 42: 3.0 (GHz) Frequency (f3) of the IF signal output by the second vector signal generator 43: 3.5 (GHz) H-polarized wave frequency (fh): 27.4 (GHz) V-polarized wave frequency (fv): 27.9 (GHz) Measuring Instrument 51: Spectrum Analyzer In this embodiment, the frequency fh of the H polarization is not simply the sum of the frequency f1 of the LO signal and the frequency f2 of the IF signal, because the phased array antenna 10 in this embodiment generates a quadruple wave of the LO signal and mixes the quadruple wave with the IF signal to frequency convert the IF signal to an RF signal. That is, the following two equations hold: fh=f2+4×f1 fv=f3+4×f1

[0043] Fig. 4(a) shows the measurement results obtained by the measuring instrument 51 (spectrum analyzer) when the relative angle between the phased array antenna 10 and the reference antenna 20 is set to α = 0°. Fig. 4(b) shows the measurement results obtained by the measuring instrument 51 when the relative angle between the phased array antenna 10 and the reference antenna 20 is set to α = 45°. The horizontal axis units are the same in Figs. 4(a) and 4(b).

[0044] As shown in FIG. 4(a), when α = 0°, the detected intensity of the V polarization is significantly lower than that of the H polarization. This is because, at α = 0°, the reference direction E is parallel to the H polarization, whereas the reference direction E is perpendicular to the V polarization. On the other hand, as shown in FIG. 4(b), when α = 45° is set, the detected intensity of the V polarization is dramatically improved compared to when α = 0°. Specifically, in this example, the detected intensity of the V polarization improved by 26.8 dB. As a result, the detected intensities of the H polarization and the V polarization are approximately the same. Note that the detected intensity of the H polarization decreased by 2.7 dB compared to when α = 0°. However, this decrease is small enough to be addressed by prior measurements and does not significantly affect the measurement. Thus, it was confirmed that simultaneous evaluation of the H polarization and the V polarization is possible by setting the relative angle between the phased array antenna 10 and the reference antenna 20 to α = 45°.

[0045] 5 is a graph showing the results of measuring the effective isotropic radiated power (EIRP) of H polarization and the effective isotropic radiated power of V polarization for each of the 64 antennas 11 included in the phased array antenna 10. The horizontal axis represents the serial numbers (0 to 63) assigned to the antennas 11. For example, when measuring antenna 11 number 0, only antenna 11 number 0 was turned ON and all antennas 11 other than antenna 0 were turned OFF.

[0046] 5, the detected strength of the H polarized wave and the V polarized wave were approximately the same for all antennas 11. Thus, according to the method of this embodiment, it is possible to simultaneously evaluate whether each antenna 11 can normally transmit and receive both the H polarized wave and the V polarized wave.

[0047] 6(a) to 6(e) are graphs showing beam patterns of the phased array antenna 10 according to this embodiment. Note that the units of the horizontal axis are the same in FIGS. 6(a) to 6(e). FIG. 6(a) shows the case where the beam directivity angle (beam direction angle) θ is −60°. FIG. 6(b) shows the case where the beam directivity angle θ is −30°. FIG. 6(c) shows the case where the beam directivity angle θ is 0°. FIG. 6(d) shows the case where the beam directivity angle θ is 30°. FIG. 6(e) shows the case where the beam directivity angle θ is 60°. Note that the numbers such as “4.85 dB” shown on the right side of each figure indicate the difference between the maximum effective isotropic radiated power of H polarization and the maximum effective radiated power of V polarization.

[0048] 6, no significant difference was observed between the beam pattern of H polarization and the beam pattern of V polarization at any beam directivity angle θ. As described above, according to the method of this embodiment, the beam pattern of H polarization and the beam pattern of V polarization can be simultaneously evaluated in the phased array antenna 10.

[0049] Example 2 The phased array antenna 10 of the evaluation system 1A shown in Fig. 2A was replaced with a phased array antenna group 30 (see Fig. 3). Then, the beam pattern of the phased array antenna group 30 was measured under the condition of α = 45°. The conditions for each frequency were the same as those in Example 1.

[0050] 7(a) to 7(e) are graphs showing beam patterns of the phased array antenna group 30 according to this embodiment. Note that the horizontal axis units are the same in FIGS. 7(a) to 7(e). FIG. 7(a) shows the case where the beam direction angle θ is −60°. FIG. 7(b) shows the case where the beam direction angle θ is −30°. FIG. 7(c) shows the case where the beam direction angle θ is 0°. FIG. 7(d) shows the case where the beam direction angle θ is 30°. FIG. 7(e) shows the case where the beam direction angle θ is 60°. Note that the numbers such as “0.31 dB” shown on the right side of each figure indicate the difference between the maximum effective radiated power of H polarization and the maximum effective radiated power of V polarization.

[0051] 7, no significant difference was observed between the beam pattern of H polarization and the beam pattern of V polarization at any beam directivity angle θ. As described above, according to the method of this embodiment, the beam pattern of H polarization and the beam pattern of V polarization can be simultaneously evaluated in the phased array antenna group 30.

[0052] Example 3 In the evaluation system 1A shown in Fig. 2A, the value of α was changed within the range of -90°≦α≦90°, and the intensity of the H-polarized wave was measured for each α. Fig. 8A is a graph showing the measured values ​​(example) and calculated values. Fig. 8B is a graph obtained by extracting the range of -55°≦α≦-35° from the graph of Fig. 8A. Fig. 8C is a graph obtained by extracting the range of 35°≦α≦55° from the graph of Fig. 8A.

[0053] As shown in Figure 8A, for example, when the absolute value of α exceeds 75°, the intensity of the H polarization is confirmed to decrease rapidly. On the other hand, as shown in Figures 8B and 8C, when the absolute value of α is within the range of 35° to 55° (35° ≦ |α| ≦ 55°), the effective radiated power of the H polarization is within a 3 dB range centered around α = 45°, and no significant change is observed. Therefore, in simultaneous evaluation of the H polarization and the V polarization, the value of α does not necessarily need to be exactly 45°; it is sufficient if the value of α is within the range of 35° to 55°. In other words, by setting α within the range of 35° to 55°, it is believed that simultaneous evaluation of the H polarization and the V polarization can be performed accurately.

[0054] However, even when α is less than 35° or greater than 55°, it is possible to simultaneously evaluate H polarization and V polarization as long as |α|≠0° and |α|≠90°.

[0055] In light of the above, in this embodiment, a phased array antenna evaluation method is proposed for evaluating a phased array antenna 10 having a plurality of antennas 11 that transmit or receive a first polarized wave (H polarized wave) and a second polarized wave (V polarized wave) whose vibration directions are orthogonal to each other, in which a reference antenna 20 is arranged opposite the phased array antenna 10 and transmits or receives radio waves that vibrate in a reference direction E, and in which the first polarized wave and the second polarized wave are simultaneously evaluated in a state in which the first direction (H polarized wave direction) in which the first polarized wave vibrates is not parallel to the reference direction E when viewed from the opposing direction in which the phased array antenna 10 and the reference antenna 20 are opposed, and the second direction (V polarized wave direction) in which the second polarized wave vibrates is not parallel to the reference direction E when viewed from the opposing direction.

[0056] With this configuration, since the reference direction E is not parallel to either the H polarization direction or the V polarization direction, it is possible to simultaneously evaluate the H polarization and the V polarization. In other words, compared to when the reference direction E is parallel to either the H polarization direction or the V polarization direction (when α = 0° or α = 90°), the intensity of both the H polarization and the V polarization can be ensured. This allows the H polarization and the V polarization to be simultaneously evaluated by the reference antenna 20. Furthermore, this method can be realized using a single reference antenna 20.

[0057] Furthermore, the relative angle α between the first direction and the reference direction E may be 35° or more and 55° or less when viewed from the opposing direction. With this configuration, the angle between the H polarization direction and the reference direction E and the angle between the V polarization direction and the reference direction E can be made approximately equal. This allows the H polarization and the V polarization to be transmitted and received at approximately the same intensity between the phased array antenna 10 and the reference antenna 20. In other words, it is possible to measure the H polarization and the V polarization at approximately the same intensity level while maintaining a sufficient S / N ratio based on the noise level of the measuring instrument. This allows the H polarization and the V polarization to be evaluated simultaneously with high accuracy.

[0058] Furthermore, the center O1 of the phased array antenna 10 and the center O2 of the reference antenna 20 may coincide when viewed from the opposing direction. According to the above-described method that enables evaluation of the H polarization and the V polarization using a single reference antenna 20, it is also possible to perform the evaluation with both centers O1 and O2 coincident in this way.

[0059] Alternatively, a first polarized wave having a first frequency and a second polarized wave having a second frequency different from the first frequency may be simultaneously transmitted from the phased array antenna 10, and the first polarized wave and the second polarized wave may be simultaneously received by the reference antenna 20. With this configuration, when the phased array antenna 10 transmits radio waves, evaluation of the H polarized wave and evaluation of the V polarized wave can be performed simultaneously.

[0060] Alternatively, a first radio wave having a first frequency may be transmitted from the reference antenna 20, and the first radio wave may be received by the phased array antenna 10. According to this configuration, when the phased array antenna 10 receives radio waves, evaluation of the H polarization and evaluation of the V polarization can be performed simultaneously.

[0061] Alternatively, a first radio wave and a second radio wave having a second frequency different from the first frequency may be transmitted from the reference antenna 20, and the first radio wave and the second radio wave may be simultaneously received by the phased array antenna. This configuration also makes it possible to perform the above-described simultaneous evaluation when the phased array antenna 10 receives radio waves.

[0062] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0063] For example, the type of reference antenna 20 is not limited to a horn antenna and can be changed as appropriate as long as it is capable of transmitting and receiving radio waves to and from the phased array antenna 10. Even in this case, by setting the relative angle α between the reference direction E of reference antenna 20 and the H polarization direction within the range of 35° to 55°, the same effects as those of the above embodiment can be obtained.

[0064] Furthermore, the phased array antenna 10 may perform only one of transmitting and receiving radio waves. Similarly, the reference antenna 20 may perform only one of transmitting and receiving radio waves.

[0065] Furthermore, the evaluation systems 1 and 2 may be provided with an angle adjustment mechanism for adjusting α. In this case, the angle adjustment mechanism may be a mechanism for rotating the phased array antenna 10 or the phased array antenna group 30, a mechanism for rotating the reference antenna 20, or a mechanism for rotating both of them.

[0066] In addition, it is possible to replace the components in the above-described embodiments with well-known components as appropriate, and the above-described embodiments and variations may be combined as appropriate, without departing from the spirit of the present invention. [Explanation of symbols]

[0067] 10...Phased array antenna 11...Antenna 20...Reference antenna E...Reference direction α...Relative angle

Claims

1. 1. A phased array antenna evaluation method for evaluating a phased array antenna having a plurality of antennas that transmit or receive first polarized waves and second polarized waves whose vibration directions are orthogonal to each other, comprising: a reference antenna that is arranged opposite the phased array antenna and transmits or receives radio waves that oscillate in a reference direction; evaluating the first polarized wave and the second polarized wave simultaneously in a state in which a first direction in which the first polarized wave oscillates is not parallel to the reference direction as viewed from a facing direction in which the phased array antenna and the reference antenna are facing each other, and a second direction in which the second polarized wave oscillates is not parallel to the reference direction as viewed from the facing direction; Phased array antenna evaluation methods.

2. When viewed from the opposing direction, the relative angle between the first direction and the reference direction is equal to or greater than 35° and equal to or less than 55°. The phased array antenna evaluation method according to claim 1 .

3. When viewed from the opposing direction, the center of the phased array antenna and the center of the reference antenna coincide with each other. The phased array antenna evaluation method according to claim 1 .

4. simultaneously transmitting the first polarized wave having a first frequency and the second polarized wave having a second frequency different from the first frequency from the phased array antenna; receiving the first polarized wave and the second polarized wave simultaneously by the reference antenna; The phased array antenna evaluation method according to any one of claims 1 to 3.

5. transmitting a first radio wave having a first frequency from the reference antenna; receiving the first radio wave by the phased array antenna; The phased array antenna evaluation method according to any one of claims 1 to 3.

6. transmitting the first radio wave and a second radio wave having a second frequency different from the first frequency from the reference antenna; receiving the first radio wave and the second radio wave simultaneously by the phased array antenna; The phased array antenna evaluation method according to claim 5.

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