Phased array antenna module, correction term calculation method, and inspection system

Abstract

This phased array antenna module comprises at least one antenna array having a plurality of antenna elements. The standard deviation of a phase shift of each of the antenna elements included in the antenna array is no more than 16.3 degrees, the phase shift being with respect to a reference phase of each of the antenna elements.

Description

Phased array antenna module, correction term calculation method, and inspection system

[0001] This application claims priority to Japanese Patent Application No. 2024-148508, filed on August 30, 2024, the contents of which are incorporated herein by reference.

[0002] A phased array antenna is an antenna that can freely change its beam pattern (antenna directivity) by adjusting at least one of the strength and phase of a signal (transmitted signal) supplied to a plurality of antenna elements or a signal (received signal) supplied from a plurality of antenna elements. In recent years, such phased array antennas have been used in various fields, including the automotive and communications fields.

[0003] In order to provide a beam pattern of a phased array antenna with a desired directivity, it is common to calibrate the phase of each antenna element. Patent Document 1 discloses that a predetermined calibration is performed on all pairs of antenna elements that are symmetrically positioned with respect to the central axis of the array.

[0004] Japanese Patent No. 5104938

[0005] In the calibration method of Patent Document 1, calibration is performed sequentially for all pairs of antenna elements that are symmetrically positioned with respect to the central axis. Therefore, as the number of antenna elements increases, the number of required calibrations increases, and the time required for calibration also increases.

[0006] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a phased array antenna module, a correction term calculation method, and an inspection system that can reduce the time required for calibration.

[0007] In order to solve the above problem, a phased array antenna module according to aspect 1 of the present invention includes at least one antenna array having a plurality of antenna elements, and the standard deviation of the phase shift of each of the antenna elements included in the antenna array relative to a reference phase is within 16.3 degrees.

[0008] A second aspect of the present invention relates to a phased array antenna module according to the first aspect, and further relates to a phase correction module that corrects the phase of each of the plurality of antenna arrays by using, as a correction term, a difference between an average value of the phase characteristics of each of the plurality of antenna arrays and the phase characteristics of each of the plurality of antenna arrays relative to the average value.

[0009] A third aspect of the present invention may be such that the phased array antenna module according to the second aspect further comprises at least one of a memory that stores the correction terms and a digital circuit unit that calculates the correction terms.

[0010] A fourth aspect of the present invention is a correction term calculation method for calculating correction terms for the phases of multiple antenna arrays included in a phased array antenna module, comprising: a phase characteristic measurement step of measuring the phase characteristics of each of the multiple antenna arrays; a characteristic average calculation step of calculating an average value of the phase characteristics of each of the multiple antenna arrays measured in the phase characteristic measurement step; and a phase difference calculation step of calculating a difference between the phase characteristic of each of the multiple antenna arrays and the average value calculated in the characteristic average calculation step, wherein the difference obtained in the phase difference calculation step is used as a correction term.

[0011] A testing system according to a fifth aspect of the present invention includes a phased array antenna module to which phase-synchronized LO signals and IF signals are input, a frequency conversion integrated circuit included in the phased array antenna module that generates an RF signal by performing frequency conversion using the LO signal and the IF signal, an antenna element included in the phased array antenna module that transmits the RF signal, and an inspector that inspects the phase of the antenna element in a transmission mode based on the RF signal, the LO signal, and the IF signal.

[0012] A sixth aspect of the present invention is the test system according to the fifth aspect, wherein the tester outputs the LO signal and the IF signal whose phases are synchronized.

[0013] A seventh aspect of the present invention may further comprise a synchronization device for synchronizing the phases of the LO signal and the IF signal input to the phased array antenna module in the inspection system according to the fifth aspect.

[0014] An inspection system according to an eighth aspect of the present invention includes a phased array antenna module to which phase-synchronized RF and LO signals are input, an antenna element included in the phased array antenna module that receives the RF signals, a frequency conversion integrated circuit included in the phased array antenna module that generates IF signals by performing frequency conversion using the RF and LO signals, and an inspector that inspects the phase of the antenna element in a receive mode based on the RF, LO, and IF signals.

[0015] A ninth aspect of the present invention may be the inspection system according to any one of the fifth to eighth aspects, further comprising a rotation table that rotates the phased array antenna module.

[0016] According to the above aspects of the present invention, it is possible to provide a phased array antenna module, a correction term calculation method, and an inspection system that can reduce the time required for calibration.

[0017] 1 is a system configuration diagram showing the configuration of a phased array antenna module according to a first embodiment. It is a block diagram showing the configuration of the beamformer integrated circuit of FIG. 1. It is a diagram explaining a coordinate system related to the phased array antenna module. It is an example of a correction term for canceling phase variations of antenna elements as a comparative example. It is an example of a correction term for explaining that phase variations of antenna elements are not canceled as an example. It is a graph showing the effect of presence or absence of phase correction on EIRP when θ is set to 0 degrees. It is a graph showing the effect of presence or absence of phase correction on EIRP when θ is set to -60 degrees. It is a graph showing the relationship between phase variations of antenna elements and relative power. It is an enlarged view of FIG. 6. It is a schematic diagram explaining a phased array antenna module according to a second embodiment. It is a sample obtained by acquiring phase characteristics for H-polarized waves of four antenna arrays (first to fourth antenna arrays). It is an enlarged view of FIG. 9. It is a diagram explaining an inspection system in a transmit mode according to a third embodiment. It is a diagram explaining an inspection system in a receive mode according to a third embodiment. It is a diagram explaining an inspection system including a turntable according to a modified example of the third embodiment. It is a diagram explaining an inspection system including a synchronizer according to a modified example of the third embodiment.

[0018] 1 is a system configuration diagram showing the configuration of a phased array antenna module 1 according to this embodiment. The phased array antenna module 1 is provided in a wireless communication device that uses, for example, a millimeter wave band and is capable of beamforming, which allows the beam pattern to be freely changed.

[0019] 1, the phased array antenna module 1 includes a plurality of beamformer integrated circuits 10, an antenna array 20, a frequency conversion integrated circuit 30, and an RF signal coupler / splitter 40. The antenna array 20 may be mounted on, for example, a first surface b1 (see FIG. 3 ) of a substrate B. The beamformer integrated circuit 10, the frequency conversion integrated circuit 30, and the like may be mounted on a second surface b2 of the substrate B.

[0020] The phased array antenna module 1 is connected to the control device 50 via a signal line 51, a control line 52, and a power line 53. RF signals and the like are transmitted and received between the control device 50 and the phased array antenna module 1 via the signal line 51. Control-related communication messages are transmitted and received between the control device 50 and the phased array antenna module 1 via the control line 52. Power is supplied from the control device 50 to the phased array antenna module 1 via the power line 53.

[0021] The beamformer integrated circuit 10 is an integrated circuit that controls the beam pattern of the antenna array 20. A plurality of antenna elements 21 that constitute the antenna array 20 are connected to each beamformer integrated circuit 10. The frequency conversion integrated circuit 30 performs frequency conversion between an intermediate frequency (IF) signal and an RF signal transmitted and received by the beamformer integrated circuit 10 and the antenna array 20.

[0022] The RF signal coupler / splitter 40 distributes the RF signals output from the frequency conversion integrated circuit 30 to each of the beamformer integrated circuits 10. The RF signal coupler / splitter 40 also combines the RF signals received by each of the beamformer integrated circuits 10 and inputs the combined signals to the frequency conversion integrated circuit 30.

[0023] 2 is a block diagram showing the configuration of the beamformer integrated circuit 10. The beamformer integrated circuit 10 includes a plurality of RF front ends (RFFEs) 5, a digital circuit 6, an analog circuit 7, and an RF signal coupler / splitter 8. There is a one-to-one correspondence between one antenna element 21 and one RF front end 5. In other words, each of the plurality of RF front ends 5 is connected to each of the plurality of antenna elements 21. Of the plurality of RF front ends 5 and the plurality of antenna elements 21, half may be for horizontal polarization, and the other half may be for vertical polarization.

[0024] The beamformer integrated circuit 10 sets the phase and intensity of each antenna element 21 for each of the horizontally polarized (H-polarized) radio waves and the vertically polarized (V-polarized) radio waves so that the direction of the composite radio waves transmitted or received from each antenna element 21 is a predetermined direction.

[0025] 2, the RF front end 5 includes a digital circuit unit 11 and an analog circuit unit 12. The digital circuit unit 11 transmits and receives control-related communication messages to and from the control device 50 via the control line 52 shown in FIG. 1. The digital circuit unit 11 controls the RF front end 5 based on the communication messages transmitted from the control device 50.

[0026] In this embodiment, communication messages related to control are transmitted and received between the phased array antenna module 1 and the control device 50 through parallel communication. That is, the digital circuit unit 11 transmits and receives communication messages related to control with the control device 50 through parallel communication. Note that the communication between the phased array antenna module 1 and the control device 50 is not limited to parallel communication. It may be serial communication such as SPI (Serial Peripheral Interface) or I2C (Inter-Integrated Circuit).

[0027] The digital circuit unit 11 is connected to the digital circuit 6 by wiring inside the beamformer integrated circuit 10. The digital circuit 6 relays communication between the digital circuit unit 11 and the control device 50. Alternatively, the digital circuit 6 communicates with the digital circuit unit 11 based on the contents of a communication message transmitted from the control device 50.

[0028] The digital circuit unit 11 includes a memory 13 serving as a storage area. The memory 13 stores a beam table used for beamforming. The beam table is a lookup table that stores multiple combinations of phase shift setting values ​​and intensity setting values ​​that are set according to the beam pattern of the antenna array 20 to be controlled.

[0029] The memory 13 is realized using, for example, a static random access memory (SRAM). Although it is preferable that the memory 13 be realized using an SRAM, the memory 13 may also be realized using a register, a dynamic random access memory (DRAM), a flash memory, or a read only memory (ROM).

[0030] The analog circuit unit 12 is a circuit that outputs an RF signal to the antenna element 21 connected to the RF front end 5 and receives an RF signal output from the antenna element 21. Under the control of the digital circuit unit 11, the analog circuit unit 12 adjusts the phase and intensity of the RF signal transmitted and received by the antenna element 21 connected to the RF front end 5.

[0031] As shown in FIG. 2 , the analog circuit unit 12 includes a phase shifter (PS) 61, a changeover switch (SW) 62, a variable gain amplifier (VGA) 63, a variable attenuator (ATT) 64, a phase inverter (PI) 65, a power amplifier (PA) 66, a changeover switch (SW) 67, a low noise amplifier (LNA) 68, a variable gain amplifier (VGA) 69, a variable attenuator (ATT) 70, and a phase inverter (PI) 71.

[0032] The phase shifter 61 adjusts the phase shift of the RF signal passing through the transmission path R1 or the RF signal passing through the reception path R2 according to the phase shift setting value in the beam table read from the memory 13 of the digital circuit unit 11. That is, the phase shifter 61 is provided in common to the transmission path R1 and the reception path R2. Alternatively, the phase shifter 61 common to the transmission path R1 and the reception path R2 may be omitted, and a phase shifter may be provided separately for the transmission path R1 and the reception path R2. The phase shifter 61 includes multiple phase shift circuits 61a. The phase adjustment amount changes by switching these phase shift circuits 61a ON / OFF. In the example of FIG. 3, one phase shifter 61 includes 46 phase shift circuits 61a, but the number of phase shift circuits 61a may be changed.

[0033] The variable gain amplifier 63 amplifies the RF signal passing through the transmission path R1 in accordance with the intensity setting value of the beam table read from the memory 13. The variable attenuator 64 attenuates the RF signal passing through the transmission path R1 in accordance with the intensity setting value of the beam table read from the memory 13. The phase inverter 65 inverts the phase of the RF signal passing through the transmission path R1 in accordance with the phase shift setting value of the beam table read from the memory 13. The power amplifier 66 amplifies the RF signal passing through the transmission path R1 by a predetermined amplification factor. By adjusting the phase shift and intensity of the RF signal passing through the transmission path R1, the beam pattern of the radio waves transmitted from the phased array antenna module 1 can be changed.

[0034] FIG. 3 is a diagram illustrating a coordinate system for the phased array antenna module 1. The X-axis direction and the Y-axis direction are directions in which multiple antenna elements 21 are arranged two-dimensionally. In this specification, the X-axis direction may be referred to as the first direction X, and the Y-axis direction may be referred to as the second direction Y. The first direction X and the second direction Y are perpendicular to each other. The first direction X and the second direction Y are also directions along the first surface b1 of the substrate B. In FIG. 3, the antenna array 20 has a total of 64 antenna elements 21, with eight rows in the first direction X and eight rows in the second direction Y. However, the number of antenna elements 21 is merely an example and may be changed.

[0035] The Z-axis direction is a direction perpendicular to the first surface b1. In this specification, the Z-axis direction may be referred to as the vertical direction Z. The vertical direction Z is perpendicular to both the first direction X and the second direction Y. The vertical direction Z is also the thickness direction of the substrate B. In Figure 3, the directivity of the beam pattern, i.e., the direction in which the transmitted and received signal strength is maximized, is represented by the vector r. The angle that the vector r makes with respect to the Z axis is referred to as the beam directivity angle θ. The angle that the vector r makes with respect to the X axis is referred to as the azimuth angle φ. The antenna directivity of the phased array antenna module 1 can be represented by the beam directivity angle θ and the azimuth angle φ.

[0036] Here, a reference phase is set for each antenna element 21 so as to obtain a predetermined antenna directivity. This reference phase is a value that ignores phase variations due to manufacturing for each antenna element 21. Actual antenna elements 21 have phase variations due to, for example, the length of the circuit connected to the antenna element 21. For this reason, if the reference phase is applied to each antenna element 21 as is, the antenna elements 21 will operate at a phase that is shifted from the reference phase. As a result, the antenna directivity of the phased array antenna module 1 will deviate from the predetermined direction. In order to operate the antenna elements 21 according to the reference phase, it is common to control the input / output signals of the antenna elements 21 at a phase obtained by adding a correction term to the reference phase so as to cancel out the phase variations for each antenna element 21.

[0037] For these reasons, in conventional phased array antenna modules, calibration is performed on each antenna element 21 to obtain a predetermined antenna directivity. Calibration is performed by determining in advance the phase variation of each antenna element 21 due to manufacturing and applying a correction term (degrees) that cancels out that phase variation. FIG. 4A is an example of a table showing correction terms for an 8-column x 8-column antenna array 20. In FIG. 4A, the numbers 0 to 7 on the vertical axis represent the numbers of the beamformer integrated circuits 10, and the numbers 0 to 7 on the horizontal axis represent the numbers of the antenna elements 21. In other words, eight beamformer integrated circuits 10 each control eight antenna elements 21, thereby controlling a total of 64 antenna elements 21.

[0038] The correction terms shown in Fig. 4A are examples of values ​​obtained by actually performing calibration on 8 columns x 8 columns of antenna elements 21. The correction terms are determined so as to cancel the phase variations in the input and output signals of each of the antenna elements 21. Calibration to obtain such correction terms can be performed by a well-known method.

[0039] The inventors of the present application investigated how the effective isotropically radiated power (EIRP) of each antenna element 21 changes when phase correction using a correction term is performed and when no correction is performed. Specifically, the power was obtained under two conditions, with and without phase correction, for each of the cases where the beam direction angle θ is set to −60 degrees and 0 degrees, and converted into EIRP. "With phase correction" refers to the case where signals input to and output from each antenna element 21 are corrected using correction terms previously acquired by calibration, as shown in FIG. 4A. "Without phase correction" refers to the case where all correction terms are set to 0 degrees or where no correction table is used, as shown in FIG. 4B.

[0040] Figure 5A shows the EIRP measurement results when aiming for θ = 0 degrees. Figure 5B shows the EIRP measurement results when aiming for θ = -60 degrees. In both Figures 5A and 5B, it can be seen that the presence or absence of phase correction has little effect on the accuracy of the beam direction and power fluctuations.

[0041] The results of extracting the maximum EIRP values ​​in FIGS. 5A and 5B are shown in Table 1 below.

[0042] As shown in Table 1, when θ = -60 degrees, the difference in EIRP between with and without phase correction was -0.1 dB. Furthermore, when θ = 0 degrees, the difference in EIRP between with and without phase correction was 0.3 dB. Here, it was assumed that there was a 0.5 dB measurement variation in power. In other words, in the example of Table 1, the difference in EIRP between with and without phase correction is equal to or less than the measurement variation. Thus, by defining an allowable range for the phase variation of the antenna element 21 such that the difference in EIRP between with and without phase correction is equal to or less than the measurement variation (0.5 dB), it is believed that the calibration work for the phased array antenna module 1 can be omitted.

[0043] Below, we will explain the conditions under which the difference in EIRP between with and without phase correction is 0.5 dB or less. A simulation was conducted to examine the degree of influence on the beam pattern by applying phase variation according to a normal distribution to antenna elements 21 arranged in an 8-element by 8-element array. As shown in FIG. 4A , the phase variation of the antenna elements 21 can be expressed as a numerical value of a correction term for canceling the variation. Furthermore, the magnitude of the phase variation of the antenna elements 21 included in one antenna array 20 can be expressed using the standard deviation σ of the correction term. A larger standard deviation σ indicates a larger phase variation of the antenna elements 21. When the standard deviation σ is 0 degrees, the phase variation of the antenna elements 21 is 0 degrees, and the difference in EIRP between with and without phase correction is also 0 dB.

[0044] For beam direction angles θ of −60 degrees and 0 degrees, 100 patterns were generated using a function that generates random numbers following a normal distribution, with the standard deviation σ of phase variation varied. For example, when θ = −60 degrees, 100 patterns were generated for σ = 5 degrees, 100 patterns for σ = 10 degrees, and 100 patterns for σ = 15 degrees. The power fluctuation value for each of the phase variation patterns of the antenna elements 21 generated in this manner was determined by simulation. Figure 6 shows the simulation results when the beam direction angle θ is set to −60 degrees. The horizontal axis of Figure 6 represents the standard deviation σ, i.e., the magnitude of phase variation of the antenna elements 21 included in one antenna array 20. The vertical axis of Figure 6 represents relative power. Relative power represents the difference in maximum EIRP at each σ value compared to the power at each direction angle when σ = 0 degrees. The larger the standard deviation σ, the greater the phase variation of the antenna element 21, which results in a tendency for the antenna directivity to decrease and the relative power to decrease.

[0045] On the vertical axis of Figure 6, the power at each directivity angle when σ = 0 degrees is taken as the reference power (0 dBr). If the relative power to the reference power is in the range of 0 dBr to -0.5 dBr, the power fluctuation at each directivity angle due to phase variation of the antenna element 21 is within the measurement variation and can be said to be sufficiently small. Curve L1 in Figure 6 is an approximation curve of the minimum value of relative power. In other words, curve L1 represents the relative power at which antenna directivity is most degraded with respect to the phase variation of the antenna element 21 under each condition, for which 100 patterns were generated. Figure 7 is an enlarged view of Figure 6. As shown in Figure 6, curve L1 has a relative power value of -0.5 dBr when σ = 16.3 degrees. From these results, the following can be said.

[0046] When the standard deviation σ of the phase variation of the antenna element 21 is 16.3 degrees, the reduction in EIRP is 0.5 dBr or less compared to when there is no phase variation at all (σ = 0 degrees). In other words, when the standard deviation σ is 16.3 degrees, the degradation of antenna directivity caused by the phase variation of the antenna element 21 becomes small enough to be indistinguishable from measurement variation. Furthermore, the smaller the standard deviation σ, the better the antenna directivity. In conclusion, when the standard deviation σ is 16.3 degrees or less, calibration to cancel the phase variation of the antenna element 21 can be omitted.

[0047] 6 etc. shows data when the beam direction angle θ is set to -60 degrees, but similar studies were also performed for θ = 0 degrees, -15 degrees, -30 degrees, and -45 degrees, and it was found that the same effect can be obtained if the standard deviation σ is 16.3 degrees or less. In other words, regardless of the value of the beam direction angle θ, if the standard deviation σ is within 16.3 degrees, calibration for canceling the phase variation of the antenna element 21 can be omitted.

[0048] For example, the substrate B may be designed so that the lengths of the feeder lines connected to each antenna element 21 are equal, so that the standard deviation σ is 16.3 degrees or less. Furthermore, as shown in FIG. 1 , the phased array antenna module 1 is composed of a frequency conversion integrated circuit 30, an RF signal coupler / splitter 40, a beamformer integrated circuit 10, antenna elements 21, and the like. Signals are split within each circuit and fed to each antenna element 21. The paths from these signal inputs between each circuit element and to each antenna may be designed to be equal in length. The range of the standard deviation σ can be determined based on design tolerances of the feeder lines, etc. In other words, the present disclosure clarifies the allowable range of the standard deviation σ, making it possible to design a phased array antenna module 1 that does not require calibration of the phase variation of the antenna elements 21.

[0049] As described above, the phased array antenna module 1 of this embodiment includes at least one antenna array 20 having a plurality of antenna elements 21. Furthermore, the standard deviation σ of the phase shift of each of the antenna elements 21 included in the antenna array 20 relative to a reference phase is set to within 16.3 degrees. With this configuration, antenna directivity can be ensured without correcting the phase shift of the transmitted and received signals of the antenna element 21. This reduces the time required for calibration work.

[0050] Second Embodiment Next, a second embodiment of the present invention will be described, which has the same basic configuration as the first embodiment. Therefore, the same components are denoted by the same reference numerals and their description will be omitted, and the following description will focus on the differences. In the first embodiment, it was described that the phase variation of the antenna elements 21 included in one antenna array 20 is within a predetermined range, making it possible to omit correction of the phase shift. In the second embodiment, a case in which multiple antenna arrays 20 are used will be described.

[0051] As shown in FIG. 8 , the phased array antenna module 1A of this embodiment includes multiple antenna arrays 20. The number of antenna arrays 20 is arbitrary. Nx antenna arrays 20 may be arranged side by side in the first direction X, and Ny antenna arrays 20 may be arranged side by side in the second direction Y, resulting in a two-dimensional arrangement overall. In this case, the phased array antenna module 1A includes Nx×Ny antenna arrays 20. Each antenna array 20 has multiple antenna elements 21. The configuration of the beamformer integrated circuit 10 for each antenna array 20 may be the same as that shown in FIGS. 1 and 2 .

[0052] When calibrating the phases of multiple antenna arrays 20, typically, one calibration signal is processed using a splitter, a balun, or the like, and then branched and supplied to the multiple antenna arrays 20. When processing the calibration signal in this manner, the splitter and balun can cause a phase difference in the calibration signal, resulting in inaccurate calibration. For example, a general-purpose splitter can cause a phase difference of approximately 4 degrees, and a general-purpose balun can cause a phase difference of approximately 5 degrees. Therefore, in this embodiment, a calibration method for more accurately calibrating the phases of multiple antenna arrays 20 will be described.

[0053] The calibration method of this embodiment includes a phase characteristic measuring step S1, a characteristic average calculating step S2, a phase difference calculating step S3, and a correction step S4.

[0054] In the phase characteristic measurement step S1, the phase characteristics of each antenna array 20 are measured. As a specific example, a phase shifter 61 (see FIG. 2) is used to change the phase of a signal input to each antenna array 20. In the example of FIG. 2, the phase shifter 61 has a total of 46 phase shift circuits 61a, and the phase of the input signal is changed by changing the number of phase shift circuits 61a that are turned on. In addition, the phase of the polarized wave (e.g., H polarization) output from each antenna array 20 is detected, and the phase characteristic of that antenna array 20 is obtained based on the phase of the input signal and the phase of the output polarized wave.

[0055] Fig. 9 shows samples of phase characteristics of the H-polarized waves of four antenna arrays 20 (first to fourth antenna arrays). The horizontal axis of Fig. 10 represents the number of active phase-shift circuits 61a. In other words, the horizontal axis of Fig. 10 represents the phase of the signal input to the antenna array 20. The vertical axis of Fig. 9 represents the phase of the H-polarized waves output from each antenna array 20.

[0056] Figure 10 is an enlarged view of Figure 9. As shown in Figure 10, the phase characteristics of the four antenna arrays 20 (first to fourth antenna arrays) have approximately the same slope, but different intercepts. The numerical values ​​of these intercepts are extracted and shown in Table 2 below.

[0057]

[0058] The "H polarization" in Table 2 is the intercept value in Fig. 10. The "V polarization" in Table 2 is the intercept value of the phase characteristic (graph omitted) for the V polarization obtained by the same method as for the H polarization. These intercept values ​​represent the phase characteristic of each antenna array 20.

[0059] Next, a characteristic average calculation step S2 is performed. In the characteristic average calculation step S2, the average value of the phase characteristics of each antenna array 20 measured in the phase characteristic measurement step S1 is calculated. The "average between antenna arrays" in Table 2 is the average value of the phase characteristics.

[0060] Next, a phase difference calculation step S3 is performed. In the phase difference calculation step S3, the difference in the phase characteristics of each antenna array 20 with respect to the average value calculated in the characteristic average calculation step S2 is calculated. For example, in the example of Table 2, for H polarization, the average between the antenna arrays is 40 degrees, and the phase characteristic of the first antenna array is 44 degrees. Therefore, the difference between the average value for H polarization (40 degrees) and the first antenna array (44 degrees) is -4 degrees. Similarly, when the difference in the phase characteristics of each antenna array 20 with respect to the average value is calculated for each of the H polarization and the V polarization, Table 3 is obtained. Note that the numerical values ​​in Tables 2 and 3 are rounded to the nearest integer.

[0061]

[0062] Next, a correction step S4 is performed. In the correction step S4, the value obtained in the phase difference calculation step S3 is used as a correction term to correct the phase of each antenna array 20. As a result, it is possible to cancel out the variation in phase characteristics for each antenna array 20.

[0063] As described above, this embodiment discloses a correction term calculation method for calculating correction terms for the phases of the multiple antenna arrays 20 included in the phased array antenna module 1A. The correction term calculation method includes a phase characteristic measurement step S1 for measuring the phase characteristics of the multiple antenna arrays 20, a characteristic average calculation step S2 for calculating an average value of the phase characteristics of the multiple antenna arrays 20 measured in the phase characteristic measurement step S1, and a phase difference calculation step S3 for calculating a difference between the phase characteristic of each antenna array 20 and the average value calculated in the characteristic average calculation step S2. The difference obtained in the phase difference calculation step S3 (e.g., a value shown in Table 3) is used as a correction term. By correcting the phases of the multiple antenna arrays 20 using such correction terms, it is possible to more accurately calibrate the phase variation among the antenna arrays 20.

[0064] The correction terms obtained by steps S1 to S4 may be stored, for example, in the memory 13 (see FIG. 2) of the digital circuit unit 11. Alternatively, the correction terms may be calculated by the digital circuit unit 11 (see FIG. 2) performing processing equivalent to steps S1 to S4.

[0065] Third Embodiment Next, a third embodiment of the present invention will be described, which has the same basic configuration as the first embodiment. Therefore, the same components are denoted by the same reference numerals, and the description thereof will be omitted, and the description will focus on the differences.

[0066] This embodiment contributes to solving problems caused by frequency conversion performed by the phased array antenna module 1. Specifically, the phased array antenna module 1 includes a frequency conversion integrated circuit 30 (see FIG. 2 ). For example, when testing the phased array antenna module 1 in transmission mode, a local oscillator (LO) signal and an IF signal are input to the frequency conversion integrated circuit 30, which then performs frequency conversion and upconversion to an RF signal of a predetermined radio frequency (e.g., 28 GHz band). The RF signal then passes through each component of the phased array antenna module 1 and propagates through space via the antenna elements 21.

[0067] Generally, when acquiring S-parameters for each component or circuit included in a single module, the input and output are set to the same frequency. By setting the input and output to the same frequency, when measuring the phase characteristics of a beamformer IC, for example, the difference between the input and output can be grasped as the characteristics of the components or circuits of the beamformer IC.

[0068] However, the input (IF signal) and output (RF signal) have different frequencies in the phased array antenna module 1. Unless the phases of the IF signal and the RF signal are synchronized, it becomes difficult to perform an inspection based on the difference in phase between the IF signal and the RF signal, and it also becomes difficult to measure the phase of the antenna element 21.

[0069] To solve these problems, this embodiment presents an inspection system 100 as shown in FIGS. 11 and 12. The inspection system 100 in FIG. 11 inspects a phased array antenna module 1 (PAAM) in transmit mode. The inspection system 100 in FIG. 12 inspects a phased array antenna module 1 in receive mode. The inspection system 100 measures the phase of an antenna element 21 included in the phased array antenna module 1 (PAAM). The inspection system 100 includes an inspector 110, a DC power supply 120, an FPGA 130, and a horn antenna 140. The inspection system 100 is housed in an anechoic chamber or the like for use.

[0070] The tester 110 is, for example, a network analyzer and has a first port 111, a second port 112, a third port 113, a fourth port 114, and a fifth port 115. The following description will be divided into a transmission mode test (FIG. 11) and a reception mode test (FIG. 12).

[0071] <Transmission Mode Inspection> As shown in FIG. 11 , the first port 111 of the inspector 110 inputs an H-polarized IF signal to the phased array antenna module 1. The second port 112 inputs a V-polarized IF signal to the phased array antenna module 1. The fifth port 115 inputs an LO signal to the phased array antenna module 1. A frequency conversion integrated circuit 30 and other components operate within the phased array antenna module 1, generating RF signals (H-polarized CW signal and V-polarized CW signal) based on the input signals. For example, the LO signal is 5 to 10 GHz, the H-polarized IF signal and the V-polarized IF signal are 2 to 8 GHz, and the H-polarized CW signal and the V-polarized CW signal are 24 to 30 GHz. The frequencies of the H-polarized CW signal and the V-polarized CW signal may be the same or different. As an example, the H-polarized CW signal is 28.0 GHz, and the V-polarized CW signal is 28.5 GHz.

[0072] The H polarized CW signal and the V polarized CW signal are transmitted from antenna array 20 of phased array antenna module 1, propagate through space, and are input to horn antenna 140. Horn antenna 140 inputs the H polarized and V polarized RF signals, respectively, to third port 113 and fourth port 114 of inspector 110.

[0073] Tester 110 detects the phase of antenna element 21 in transmit mode based on the signals input and output to each of ports 111 to 115. Here, since the H polarization IF signal, V polarization IF signal, and LO signal are generated and output by the same tester 110, the phases of each signal can be synchronized. Therefore, it is possible to accurately measure the phase of antenna element 21 based on the phase difference between the signal output from tester 110 and the signal input to tester 110. Note that tester 110 may be used to test not only the phase but also the power of the H polarization CW signal and the V polarization CW signal.

[0074] 12 , the third port 113 and the fourth port 114 of the inspector 110 input H-polarized and V-polarized RF signals to the horn antenna 140. The horn antenna 140 transmits H-polarized CW signals and V-polarized CW signals. The H-polarized CW signals and V-polarized CW signals propagate through space and are received by the antenna elements 21 of the phased array antenna module 1. The fifth port 115 of the inspector 110 inputs an LO signal to the phased array antenna module 1. Inside the phased array antenna module 1, the frequency conversion integrated circuit 30 and the like operate to generate H-polarized IF signals and V-polarized IF signals based on the input signals.

[0075] The H polarization IF signal and the V polarization IF signal are input to a first port 111 and a second port 112 of the inspector 110. For example, the LO signal is 5 to 10 GHz, the H polarization IF signal and the V polarization IF signal are 2 to 8 GHz, and the H polarization CW signal and the V polarization CW signal are 24 to 30 GHz. The frequencies of the H polarization CW signal and the V polarization CW signal may be the same or different. As an example, the H polarization CW signal is 28.0 GHz, and the V polarization CW signal is 28.5 GHz.

[0076] Tester 110 detects the phase of antenna element 21 in receive mode based on the signals input and output to each of ports 111 to 115. Here, because the RF signal and LO signal for each of the H polarization and V polarization are generated and output by the same tester 110, the phases of the signals can be synchronized. Therefore, it is possible to accurately measure the phase of antenna element 21 based on the phase difference between the signal output from tester 110 and the signal input to tester 110. Note that tester 110 may be used to test not only the phase but also the power of the H polarization CW signal and the V polarization CW signal.

[0077] <Inspection System with Rotating Table> As shown in Fig. 13, the inspection system 100A may include a rotating table 150. By using the rotating table 150 to change the attitude of the phased array antenna module 1, it is possible to inspect the performance of the phased array antenna module 1 not only when it is facing the horn antenna 140 directly, but also when it is tilted relative to the horn antenna 140. The rotating table 150 may be rotatable within a range of ±180 degrees or ±90 degrees, with the attitude facing the horn antenna 140 being set to 0 degrees, for example. Although Fig. 13 shows the case of inspecting the phased array antenna module 1 in the transmission mode, the phased array antenna module 1 in the reception mode may also be inspected.

[0078] In FIG. 11 , the tester 110 outputs an IF signal and an LO signal whose phases are synchronized. However, for example, the tester 110 may output one of the IF signal and the LO signal, and the other may be output from another signal source. For example, in FIG. 14 , the test system 100B includes a local oscillator 160 and a synchronizer 170. The local oscillator 160, which is different from the tester 110, outputs the LO signal. The synchronizer 170 includes a phase shift circuit and the like, and is capable of synchronizing the phases of multiple signals. The synchronizer 170 receives the IF signal for H polarization and the IF signal for V polarization output by the tester 110, and the LO signal output by the local oscillator 160.

[0079] The synchronizer 170 synchronizes the phases of the input signals and inputs them to the phased array antenna module 1. In this case, too, the IF signal and the LO signal whose phases are synchronized are input to the phased array antenna module 1, so that the same effect as in Fig. 11 can be obtained. Similarly, in the case of the receive mode (Fig. 12), the synchronizer 170 may be used so that the phases of the RF signals (H polarization CW signal and V polarization CW signal) and the LO signal input to the phased array antenna module 1 are synchronized.

[0080] As described above, the inspection system 100 may include: a phased array antenna module 1 to which phase-synchronized LO signals and IF signals are input; a frequency conversion integrated circuit 30 included in the phased array antenna module 1 that generates RF signals (H polarization CW signals and V polarization CW signals) by performing frequency conversion using the LO signals and IF signals (H polarization IF signals and V polarization IF signals); an antenna element 21 included in the phased array antenna module 1 that transmits the RF signals; and an inspector 110 that inspects the phase of the antenna element 21 in transmission mode based on the RF signals, the LO signals, and the IF signals.

[0081] The tester 110 may output the LO signal and the IF signal whose phases are synchronized. Alternatively, the test system 100B may include a synchronizer 170 that synchronizes the phases of the LO signal and the IF signal input to the phased array antenna module 1.

[0082] The inspection system 100 may also include a phased array antenna module 1 to which phase-synchronized RF and LO signals are input, an antenna element 21 included in the phased array antenna module 1 and which receives the RF signal, a frequency conversion integrated circuit 30 included in the phased array antenna module 1 and which generates an IF signal by performing frequency conversion using the RF and LO signals, and an inspector 110 which inspects the phase of the antenna element 21 in receive mode based on the RF, LO, and IF signals.

[0083] The inspection system 100A may also include a rotation table 150 that rotates the phased array antenna module 1.

[0084] The technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Within the spirit of the present invention, the components in the above-described embodiments can be replaced with well-known components as appropriate, and the above-described embodiments and modifications can be combined as appropriate.

[0085] According to the above aspects of the present invention, it is possible to provide a phased array antenna module, a correction term calculation method, and an inspection system that can reduce the time required for calibration.

[0086] REFERENCE SIGNS LIST 1, 1A... Phased array antenna module 11... Digital circuit section 13... Memory 20... Antenna array 21... Antenna element 30... Frequency conversion integrated circuit 100... Inspection system 110... Inspection device 150... Rotating table 170... Synchronization device

Claims

1. A phased array antenna module comprising at least one antenna array having a plurality of antenna elements, wherein the standard deviation of the phase shift of each of the antenna elements included in the antenna array relative to a reference phase is within 16.3 degrees.

2. The phased array antenna module according to claim 1, comprising a plurality of said antenna arrays, wherein the phase of each of said plurality of antenna arrays is corrected using, as a correction term, the difference between the average value of the phase characteristics of each of said plurality of antenna arrays and the phase characteristics of each of said plurality of antenna arrays relative to said average value.

3. The phased array antenna module according to claim 2, further comprising at least one of a memory that stores said correction terms and a digital circuit unit that calculates said correction terms.

4. A correction term calculation method for calculating correction terms for the phases of multiple antenna arrays included in a phased array antenna module, comprising: a phase characteristic measurement step for measuring the phase characteristics of each of the multiple antenna arrays; a characteristic average calculation step for calculating an average value of the phase characteristics of each of the multiple antenna arrays measured in the phase characteristic measurement step; and a phase difference calculation step for calculating the difference between the phase characteristic of each of the multiple antenna arrays and the average value calculated in the characteristic average calculation step, wherein the difference obtained in the phase difference calculation step is used as a correction term.

5. An inspection system comprising: a phased array antenna module to which phase-synchronized LO signals and IF signals are input; a frequency conversion integrated circuit included in the phased array antenna module that generates an RF signal by performing frequency conversion using the LO signal and the IF signal; an antenna element included in the phased array antenna module that transmits the RF signal; and an inspector that inspects the phase of the antenna element in transmission mode based on the RF signal, the LO signal, and the IF signal.

6. The test system of claim 5, wherein the tester outputs the LO signal and the IF signal in phase.

7. The inspection system of claim 5, further comprising a synchronizer for synchronizing the phases of the LO signal and the IF signal input to the phased array antenna module.

8. A test system comprising: a phased array antenna module to which phase-synchronized RF and LO signals are input; an antenna element included in the phased array antenna module and receiving the RF signal; a frequency conversion integrated circuit included in the phased array antenna module that generates an IF signal by performing frequency conversion using the RF signal and the LO signal; and a tester that tests the phase of the antenna element in a receive mode based on the RF signal, the LO signal, and the IF signal.

9. The inspection system according to any one of claims 5 to 8, further comprising a rotating table for rotating the phased array antenna module.

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