Reception device

Abstract

A reception device (1) comprises: a plurality of antenna elements (11); a plurality of phase shifters (13); a plurality of gain adjusters (14); and a synthesis circuit (15). A phase shifter (13), which corresponds to an antenna element (11b) operating as a cross-polarization element, adjusts the phase of a reception signal on the basis of a phase adjustment amount. The phase adjustment causes the phase of the reception signal generated by the antenna element (11b) to be the opposite of the phase of a cross-polarization component included in a reception signal generated by an antenna element (11a). A gain adjuster (14), which corresponds to the antenna element (11a) operating as a main polarization element, adjusts the amplitude of the reception signal on the basis of a gain suppression amount. The gain suppression amount causes the amplitude of the cross-polarization component of the reception signal generated by the antenna element (11a) to approach the amplitude of the reception signal generated by the antenna element (11b).

Description

Receiving device

[0001] The present disclosure relates to a receiving device.

[0002] Radio waves received by a phased array receiving device include a primary polarization component and a cross-polarization component that intersects with the primary polarization component. As the scanning range of the receiving device becomes wider, the cross-polarization component increases. If the amplitude of the cross-polarization component increases relative to the amplitude of the primary polarization component, the communication quality of the receiving device deteriorates. Some receiving devices have a function to reduce the cross-polarization component to prevent deterioration of communication quality. An example of this type of receiving device is disclosed in Patent Document 1.

[0003] The antenna device disclosed in Patent Document 1 has a circularly polarized element antenna and a cross-polarized element antenna, and generates a signal with the same amplitude and opposite phase as the cross-polarized component contained in the output of the circularly polarized element antenna in the cross-polarized element antenna, and suppresses the cross-polarized component by combining the generated signal with the output of the circularly polarized element antenna.

[0004] JP 2011-91625 A

[0005] In the antenna device disclosed in Patent Document 1, the amplitude and phase of the signal output by the cross-polarized element antenna are determined in order to reduce the cross-polarized component included in the output of the circularly polarized element antenna. In detail, the amplitude of the cross-polarized component included in the output of the circularly polarized element antenna is made close to the amplitude of the output of the cross-polarized element antenna, and the output of the cross-polarized element antenna is made to have the opposite phase to the cross-polarized component included in the output of the circularly polarized element antenna, thereby canceling out the cross-polarized component included in the output of the circularly polarized element antenna.

[0006] In order to bring the amplitude of the cross-polarized component included in the output of the circularly polarized element antenna closer to the amplitude of the output of the cross-polarized element antenna, it is necessary to adjust the ratio of the number of circularly polarized element antennas to the number of cross-polarized element antennas or to attenuate the output of the circularly polarized element antenna. However, if the number of circularly polarized element antennas is reduced relative to the number of cross-polarized element antennas, the antenna gain decreases. Furthermore, attenuating the output of the circularly polarized element antenna increases noise. Therefore, depending on the ratio of the number of circularly polarized element antennas to the number of cross-polarized element antennas and the degree of attenuation of the output of the circularly polarized element antenna, the communication quality of the antenna device may deteriorate.

[0007] The present disclosure has been made in consideration of the above circumstances, and aims to provide a receiving device with high communication quality.

[0008] To achieve the above object, a receiving device according to the present disclosure is a receiving device for receiving radio waves including a primary polarization component and a cross-polarization component that crosses the primary polarization component, and includes a plurality of antenna elements, a plurality of phase shifters, a plurality of gain adjusters, and a combining circuit. The antenna elements operate as primary polarization elements that receive the primary polarization component or as cross-polarization elements that receive the cross-polarization component, and receive the radio waves to generate a received signal. The phase shifters are associated with the antenna elements, and when the corresponding antenna elements operate as primary polarization elements, they adjust the phase of the received signal generated by the corresponding antenna element based on a predetermined phase shift amount, and when the corresponding antenna elements operate as cross-polarization elements, they adjust the predetermined phase shift amount in accordance with a phase adjustment amount, and adjust the phase of the received signal generated by the corresponding antenna element based on the adjusted phase shift amount. The gain adjuster is provided corresponding to the antenna element, and when the corresponding antenna element operates as a primary polarization element, adjusts a predetermined gain in accordance with a gain suppression amount, and adjusts the amplitude of a received signal generated by the corresponding antenna element based on the adjusted gain. When the corresponding antenna element operates as a cross-polarized element, adjusts the amplitude of the received signal generated by the corresponding antenna element based on the predetermined gain. The combining circuit combines the received signals whose phases have been adjusted by the phase shifters and whose amplitudes have been adjusted by the gain adjuster. The gain suppression amount is a gain suppression amount that brings the amplitude of the cross-polarized component included in the received signal generated by the antenna element operating as a primary polarization element closer to the amplitude of the received signal generated by the antenna element operating as a cross-polarized element, within a range in which the degradation of a figure of merit indicating the communication quality of the receiving device falls within a target range. The phase adjustment amount is a phase adjustment amount that makes the phase of the received signal generated by the antenna element operating as a cross-polarized element opposite the phase of the cross-polarized component included in the received signal generated by the antenna element operating as a primary polarization element.

[0009] A receiving device according to the present disclosure adjusts the phase of a received signal generated by an antenna element operating as a cross-polarized element based on a phase shift amount adjusted in accordance with a phase adjustment amount. The receiving device adjusts the amplitude of a received signal generated by an antenna element operating as a primary polarization element based on a gain adjusted in accordance with a gain suppression amount. The gain suppression amount is a gain suppression amount that brings the amplitude of the cross-polarized component included in the received signal generated by the antenna element operating as a primary polarization element closer to the amplitude of the received signal generated by the antenna element operating as a cross-polarized element, within a range in which the degradation of a figure of merit indicating the communication quality of the receiving device falls within a target range. By combining the received signals that have been adjusted in phase and amplitude, the cross-polarized component included in the received signal generated by the antenna element operating as a primary polarization element is canceled out, resulting in a receiving device with high communication quality.

[0010] FIG. 1 is a block diagram showing the configuration of a receiving device according to an embodiment; FIG. 2 is a diagram showing an example of a method for arranging antenna elements in an embodiment; FIG. 3 is a diagram showing another example of a method for arranging antenna elements in an embodiment; FIG. 4 is a diagram showing another example of a method for arranging antenna elements in an embodiment; FIG. 5 is a diagram showing a hardware configuration of a control unit of a receiving device according to an embodiment;

[0011] Hereinafter, a receiving device according to an embodiment of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or equivalent parts are designated by the same reference numerals, and their description will not be repeated in principle.

[0012] A receiving device according to an embodiment will be described using an active phased array antenna as an example of a receiving device. The receiving device 1 shown in Fig. 1 captures radio waves from a satellite, for example, linearly polarized waves emitted from the satellite. Capturing radio waves here means receiving the radio waves. The receiving device 1 includes a plurality of antenna elements 11 that receive the radio waves and generate received signals, an antenna unit 10 that adjusts the phase and amplitude of the received signals and outputs a composite signal, and a control unit 20 that controls each unit of the receiving device 1.

[0013] The antenna unit 10 includes a plurality of low-noise amplifiers 12 that amplify received signals, a plurality of phase shifters 13 that adjust the phase of the received signals, a plurality of gain adjusters 14 that adjust the amplitude of the received signals, and a combining circuit 15 that combines the received signals whose phases have been adjusted by the phase shifters 13 and whose amplitudes have been adjusted by the gain adjusters 14, and outputs a combined signal. The antenna unit 10 is configured on a single board. Note that the low-noise amplifiers 12, phase shifters 13, and gain adjusters 14 may each be discrete components, or may be configured on a single IC (Integrated Circuit) chip.

[0014] The control unit 20 includes an amplitude detection unit 21 that detects the amplitude of the combined signal, a gain suppression amount determination unit 22 that determines a gain suppression amount indicating the amount of amplitude adjustment in the gain adjuster 14 from the amplitude of the combined signal, an element control unit 23 that controls the antenna elements 11, a phase detection unit 24 that detects the phase of the combined signal, and a phase adjustment amount determination unit 25 that determines a phase adjustment amount indicating the amount of phase adjustment in the phase shifter 13 from the phase of the combined signal. In FIG. 1 , to avoid complexity of the diagram, lines connecting the control unit 20 to other components of the receiving device 1 are simplified or omitted. Note that a separate device may be used to detect the amplitude and phase of the combined signal and determine the gain suppression amount and phase adjustment amount before operation of the receiving device 1 begins. In this case, the amplitude detection unit 21, the gain suppression amount determination unit 22, the phase detection unit 24, and the phase adjustment amount determination unit 25 are not necessarily required as components of the receiving device 1. The predetermined gain suppression amount and phase adjustment amount are stored in a memory 82 (described later) by the control unit 20 and supplied to the gain adjuster 14 and the phase shifter 13, respectively.

[0015] The radio waves received by the receiving device 1 include a main polarization component and a cross polarization component that crosses the main polarization component. As an example, in a receiving device 1 that receives vertically polarized waves, the main polarization component is vertically polarized and the cross polarization component is horizontally polarized. As another example, in a receiving device 1 that receives horizontally polarized waves, the main polarization component is horizontally polarized and the cross polarization component is vertically polarized.

[0016] The antenna element 11 operates as a primary polarization element that receives the primary polarization component or a cross polarization element that receives the cross polarization component. In the example of FIG. 1 , the antenna element 11 that operates as the primary polarization component is designated as antenna element 11a, and the antenna element 11 that operates as the cross polarization component is designated as antenna element 11b. In FIG. 1 , the antenna element 11a is shown in white, and the antenna element 11b is shown in black. The antenna element 11a and the antenna element 11b each receive radio waves and generate a received signal. The antenna element 11a receives the primary polarization component, but the received signal generated by the antenna element 11a includes a cross polarization component in addition to the primary polarization component.

[0017] The antenna elements 11 are preferably arranged at positions where they can suppress the occurrence of grating lobes in the antenna pattern of the main polarization, thereby suppressing an increase in the side lobe level. As an example, as shown in Fig. 2, the antenna elements 11 are arranged at equal intervals in a predetermined arrangement region 101 on a substrate 100 made of, for example, a dielectric material. The arrangement region 101 has, for example, a square shape, specifically, a rectangular shape.

[0018] In Fig. 2, antenna element 11a, which is an antenna element 11 operating as a primary polarization element, is indicated by a white circle, and antenna element 11b, which is an antenna element 11 operating as a cross polarization element, is indicated by a black circle. At least one of the antenna elements 11 arranged adjacent to the boundary line of arrangement area 101 is antenna element 11b operating as a cross polarization element. In particular, at least one of the antenna elements 11 arranged adjacent to at least one side of rectangular arrangement area 101 is antenna element 11b. In the example of Fig. 2, the antenna element 11 arranged adjacent to the upper side of arrangement area 101 in the drawing is antenna element 11b.

[0019] By arranging the antenna elements 11b as described above, the arrangement shape of the antenna elements 11a, which are the antenna elements 11 operating as the main polarization elements, becomes approximately square, approximately circular, or approximately elliptical. As a result, the aperture shape of the main polarization becomes a shape that can be considered to be square, circular, or elliptical, and the occurrence of grating lobes is suppressed. In the example of Figure 2, by arranging the antenna elements 11a in a shape that can be considered to be rectangular, the occurrence of grating lobes is suppressed and an increase in the side lobe level is suppressed.

[0020] As another example, as shown in Fig. 3, at least one of the antenna elements 11 arranged adjacent to each vertex of a rectangular arrangement area 101 is an antenna element 11b that operates as a cross-polarized element. In the example of Fig. 3, the antenna elements 11 arranged adjacent to the four corners of the arrangement area 101 are antenna elements 11b. By arranging the antenna elements 11b in this manner, the arrangement shape of the antenna elements 11a becomes approximately circular or approximately elliptical. As a result, the aperture shape of the main polarization becomes a shape that can be considered circular or elliptical, and the occurrence of grating lobes is suppressed.

[0021] 4, among the antenna elements 11b that function as cross-polarized elements, the distance d between adjacent antenna elements 11b is equal to or greater than a threshold determined in accordance with the number of antenna elements 11a and 11b. By making the distance d between adjacent antenna elements 11b equal to or greater than the threshold, the antenna elements 11b are dispersed and arranged in the arrangement area 101. As a result, the occurrence of grating lobes is suppressed.

[0022] 1, the low-noise amplifier 12 is provided in correspondence with the antenna element 11. The low-noise amplifier 12 amplifies the received signal input from the antenna element 11 and outputs the amplified received signal. The low-noise amplifier 12 that receives the received signal from the antenna element 11a is referred to as low-noise amplifier 12a, and the low-noise amplifier 12 that receives the received signal from the antenna element 11b is referred to as low-noise amplifier 12b.

[0023] The phase shifters 13 are provided corresponding to the antenna elements 11. The phase shifter 13 corresponding to the antenna element 11a is referred to as phase shifter 13a, and the phase shifter 13 corresponding to the antenna element 11b is referred to as phase shifter 13b. The phase shifter 13a adjusts the phase of the received signal generated by the corresponding antenna element 11a based on a predetermined phase shift amount. Specifically, the phase shifter 13a adjusts the phase of the received signal generated by the corresponding antenna element 11a and amplified by the low-noise amplifier 12a.

[0024] Phase shifter 13b adjusts the predetermined phase shift amount in accordance with the phase adjustment amount supplied from control unit 20, and adjusts the phase of the received signal generated by corresponding antenna element 11b based on the adjusted phase shift amount. When no phase adjustment amount is supplied from control unit 20, phase shifter 13b adjusts the phase of the received signal generated by corresponding antenna element 11b based on the predetermined phase shift amount, and reduces the gain of low-noise amplifier 12b or gain adjuster 14b to sufficiently reduce the amplitude of the received signal.

[0025] The phase shifters 13a and 13b receive and store information about a predetermined phase shift amount for obtaining a desired antenna directivity in the receiving device 1 from the control unit 20 or an external device other than the receiving device 1. In detail, the phase shifter 13a adjusts the phase by a predetermined phase shift amount for obtaining a desired antenna directivity, and the phase shifter 13b adjusts the phase by a phase shift amount obtained by changing the predetermined phase shift amount to a predetermined phase adjustment amount for obtaining the desired antenna directivity. By performing the phase adjustment described above by the phase shifters 13a and 13b, the phase of the received signal generated by the antenna element 11b, amplified by the low-noise amplifier 12b, and phase-adjusted by the phase shifter 13b is the opposite phase to the phase of the cross-polarized component included in the received signal generated by the antenna element 11a, amplified by the low-noise amplifier 12a, and phase-adjusted by the phase shifter 13a.

[0026] The gain adjusters 14 are provided corresponding to the antenna elements 11. The gain adjuster 14 corresponding to the antenna element 11a is referred to as the gain adjuster 14a, and the gain adjuster 14 corresponding to the antenna element 11b is referred to as the gain adjuster 14b. The gain adjuster 14a adjusts a predetermined gain in accordance with a gain suppression amount supplied from the control unit 20, and adjusts the amplitude of the received signal generated by the corresponding antenna element 11a based on the adjusted gain. Specifically, the gain adjuster 14a adjusts the amplitude of the received signal generated by the antenna element 11a, amplified by the low-noise amplifier 12a, and whose phase is adjusted by the phase shifter 13a, based on the gain adjusted in accordance with the gain suppression amount. When the gain suppression amount is not supplied from the control unit 20, the gain adjuster 14a adjusts the amplitude of the received signal generated by the corresponding antenna element 11a based on the predetermined gain.

[0027] The gain adjuster 14b adjusts the amplitude of the received signal generated by the corresponding antenna element 11b based on a predetermined gain. Specifically, the gain adjuster 14b adjusts the amplitude of the received signal generated by the antenna element 11b, amplified by the low-noise amplifier 12b, and whose phase has been adjusted by the phase shifter 13b.

[0028] The gain adjusters 14a and 14b store information about gains that are predetermined based on the amplitude of the received signal, the linearity of the amplifier, etc. The gain adjusters 14a and 14b each have, for example, a variable amplifier with an adjustable gain. The variable amplifier included in the gain adjuster 14a adjusts the gain in accordance with the gain suppression amount supplied from the control unit 20, and amplifies the input received signal.

[0029] As a result of the gain adjusters 14a and 14b adjusting the amplitude as described above, the amplitude of the cross-polarized component contained in the received signal that is generated by the antenna element 11a, amplified by the low-noise amplifier 12a, has its phase adjusted by the phase shifter 13a, and has its amplitude adjusted by the gain adjuster 14a approaches the amplitude of the received signal that is generated by the antenna element 11b, amplified by the low-noise amplifier 12b, has its phase adjusted by the phase shifter 13b, and has its amplitude adjusted by the gain adjuster 14b.

[0030] The combining circuit 15 combines the input received signals. Specifically, the combining circuit 15 combines the received signal generated by the antenna element 11a, amplified by the low-noise amplifier 12a, phase-adjusted by the phase shifter 13a, and amplitude-adjusted by the gain adjuster 14a, with the received signal generated by the antenna element 11b, amplified by the low-noise amplifier 12b, phase-adjusted by the phase shifter 13b, and amplitude-adjusted by the gain adjuster 14b. The combining circuit 15 transmits the signal obtained by combining the received signals to a receiving circuit (not shown).

[0031] By combining the received signals whose phases have been adjusted by the phase shifters 13 a and 13 b and whose amplitudes have been adjusted by the gain adjusters 14 a and 14 b as described above, the cross-polarized component contained in the received signal generated by the antenna element 11 a is canceled by the received signal generated by the antenna element 11 b. As a result, the cross-polarized component contained in the output of the combining circuit 15 is sufficiently reduced.

[0032] In order to sufficiently reduce the cross-polarized components contained in the received signal generated by antenna element 11a by the received signal generated by antenna element 11b, the control unit 20 adjusts the amount of gain suppression supplied to gain adjuster 14a, the amount of phase adjustment supplied to phase shifter 13b, and the ratio between the number of antenna elements 11a and the number of antenna elements 11b.

[0033] 5 shows the hardware configuration of the control unit 20 included in the receiving device 1 having the above configuration. The control unit 20 includes a processor 81, a memory 82, and an interface 83. The processor 81, the memory 82, and the interface 83 are connected to one another via a bus 80. The processor 81 includes any electronic circuit including a transistor, and is considered to be a circuit or a processor circuit.

[0034] The functions of the control unit 20 are realized by software, firmware, which is software built into the electronic device, or a combination of software and firmware. The software is written as a program and stored in the memory 82. The processor 81 reads and executes the program stored in the memory 82, thereby realizing the functions of the above-mentioned units. In other words, the memory 82 stores a program for executing the processing of the control unit 20.

[0035] The memory 82 includes, for example, non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read-Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable and Programmable Read-Only Memory), magnetic disk, flexible disk, optical disk, compact disk, mini disk, DVD (Digital Versatile Disc), etc.

[0036] The control unit 20 is connected to the antenna unit 10 via an interface 83. The interface 83 has an interface module that complies with one or more standards depending on the connection destination.

[0037] The control unit 20 included in the receiving device 1 having the above configuration performs the gain suppression amount determination process shown in FIG. 6 . To perform the gain suppression amount determination process, the element control unit 23 operates each antenna element 11 as a primary polarization element. In particular, the element control unit 23 operates each antenna element 11 as a primary polarization element, by setting the phase conditions of the V (Vertical) port and H (Horizontal) port of each antenna element 11, which is a circular antenna element, to 0 degrees and 90 degrees, respectively. Furthermore, when operating each antenna element 11 as a cross-polarized element, the element control unit 23 sets the phase conditions of the V port and H port of each antenna element 11, which is a circular antenna element, to 0 degrees and −90 degrees, respectively.

[0038] The control unit 20 calculates the cross polarization discrimination degree γ from the radiation pattern of the main polarization component and the cross polarization component when each antenna element 11 operates as a main polarization element. ０ (Step S11). Specifically, the amplitude detector 21 detects the amplitudes of the main polarization component and the cross polarization component of the received signal generated by each antenna element 11 when the antenna element 11 operates as a main polarization element. Specifically, the amplitude detector 21 detects the amplitudes of the main polarization component and the cross polarization component from the result of combining the outputs of the gain adjusters 14a. When combining the outputs of the gain adjusters 14a, the gain of the gain adjuster 14b or the low-noise amplifier 12b is reduced to make the output of the gain adjuster 14b sufficiently small.

[0039] The radiation pattern shown in Fig. 7 is obtained from the amplitudes of the main polarization component and the cross polarization component detected by the amplitude detector 21. The horizontal axis of Fig. 7 indicates the angle (unit: degrees) from the front direction of the receiving device 1, and the vertical axis indicates the amplitude (unit: dB). In the example of Fig. 7, the difference between the amplitude of the main polarization component and the amplitude of the cross polarization component at a scan angle of 45 degrees is 10 dB. The gain suppression amount determiner 22 obtains the amplitude difference between the main polarization component and the cross polarization component detected by the amplitude detector 21 for each scan angle, and calculates the maximum value of the amplitude difference obtained for each scan angle as the cross polarization discrimination degree γ ０ Let's say.

[0040] When some of the antenna elements 11 are operated as cross-polarized elements without amplitude adjustment by the gain adjuster 14a, the antenna gain is reduced compared to when each antenna element 11 operates as a primary polarization element. The amount of reduction G in antenna gain caused by operating some of the antenna elements 11 as cross-polarized elements is expressed by the following equation (1). In the following equation (1), N ｃ indicates the number of antenna elements 11a, and N ｘ indicates the number of antenna elements 11b. When at least one of the antenna elements 11 operates as a cross-polarized element, the number N of antenna elements 11b in the following formula (1) is ｘ is 1 or more, and N ｃ / (N ｃ +N ｘ ) is less than 1, the amount of reduction G in the antenna gain is a negative value. ｘ As the value of θ increases, the absolute value of the reduction amount G of the antenna gain increases.

[0041]

[0042] As described above, when the gain adjuster 14a adjusts the amplitude, specifically, when the amplitude is attenuated, the antenna gain further decreases. ｘ As a function of the gain suppression amount, the amount of antenna gain reduction caused by an increase in the number of cross-polarized elements can be obtained when some of the antenna elements 11 are operated as cross-polarized elements and the gain adjuster 14a attenuates the amplitude of the received signal generated by the antenna element 11a operating as the main polarization element. In other words, the relationship between the amount of gain suppression and the amount of antenna gain reduction caused by an increase in the number of cross-polarized elements can be obtained. In particular, the gains of the main polarization and cross-polarized waves at the antenna elements 11a and 11b and the number N of antenna elements 11b can be calculated based on the formula for calculating the cross polarization discrimination. ｘ is expressed by the following formula (3) using a variable X expressed by the following formula (2). ｍ denotes the amount of gain suppression supplied to the gain adjuster 14a, and γ ｓindicates a predetermined target value of cross polarization discrimination. The gain suppression amount is, for example, a numerical value representing the amount of attenuation in the gain adjuster 14a, and is 1 when no attenuation is performed. In the following formula (3), N is the total number of antenna elements 11, and N is the number of antenna elements 11a. ｃ and the number N of antenna elements 11b ｘ is the sum of the above.

[0043]

[0044]

[0045] As shown in FIG. 6 , the gain suppression amount determination unit 22 applies the above equations (2) and (3) to the above equation (1) to determine the relationship between the gain suppression amount and the amount of antenna gain reduction due to an increase in the number of cross-polarized elements (step S12). An example of the relationship between the gain suppression amount and the amount of antenna gain reduction due to an increase in the number of cross-polarized elements is shown in FIG. 8 . The horizontal axis of FIG. 8 represents the amount of gain suppression (unit: dB), and the vertical axis represents the amount of antenna gain reduction due to an increase in the number of cross-polarized elements (unit: dB). FIG. 8 also shows the absolute value of the amount of antenna gain reduction due to an increase in the number of cross-polarized elements. If the ratio of the number of antenna elements 11a to the total number of antenna elements 11 remains the same, the absolute value of the amount of antenna gain reduction due to an increase in the number of cross-polarized elements decreases as the gain suppression amount increases. In other words, as the gain suppression amount of the gain adjuster 14a increases, the contribution of the increase in cross-polarized elements to the amount of antenna gain reduction decreases. As the gain suppression amount of the gain adjuster 14a decreases, the contribution of the increase in cross-polarized elements to the amount of antenna gain reduction increases.

[0046] The gain adjuster 14a includes a low noise amplifier and at least one variable amplifier. １ , the noise figure is NF １ The gain of the first variable amplifier is G ２ , the noise figure is NF ２ The gain of the third variable amplifier is G ３ , the noise figure is NF ３ Then, the noise figure NF by the gain adjuster 14a is expressed by the following equation (4): ２ , G ３is adjusted according to the amount of gain suppression.

[0047]

[0048] As shown in Fig. 6, the gain suppression amount determination unit 22 determines the relationship between the gain suppression amount and the deterioration amount of the noise figure NF based on the above equation (4) (step S13). An example of the relationship between the gain suppression amount and the deterioration amount of the noise figure NF is shown in Fig. 9. The horizontal axis of Fig. 9 represents the gain suppression amount (unit: dB), and the vertical axis represents the absolute value of the deterioration amount of the noise figure NF (unit: dB). When the gain suppression amount in the gain adjuster 14a increases, the deterioration amount of the noise figure NF also increases.

[0049] As shown in FIG. 6 , the gain suppression amount determination unit 22 determines the relationship between the amount of gain suppression and the degradation of a figure of merit (G / T) ratio, which indicates the communication quality of the receiving device 1, from the relationship between the amount of gain suppression calculated in step S12 and the amount of antenna gain reduction due to an increase in the number of cross-polarized elements, and the relationship between the amount of gain suppression and the degradation of the noise figure NF calculated in step S13 (step S14). More specifically, an example of the relationship between the amount of gain suppression and the amount of antenna gain reduction and the relationship between the amount of gain suppression and the degradation of the noise figure is shown in FIG. 10 . The horizontal axis of FIG. 10 represents the amount of gain suppression (unit: dB), the vertical axis on the right represents the amount of antenna gain reduction (unit: dB) due to an increase in the number of cross-polarized elements, and the vertical axis on the left represents the degradation of the noise figure NF (unit: dB). In FIG. 10 , the relationship between the amount of gain suppression and the amount of antenna gain reduction due to an increase in the number of cross-polarized elements is shown by a thin solid line, and the relationship between the amount of gain suppression and the degradation of the noise figure is shown by a thick solid line.

[0050] The gain suppression amount determination unit 22 obtains the relationship between the gain suppression amount and the degradation amount of the G / T ratio by multiplying the antenna gain reduction amount corresponding to the same gain suppression amount by the degradation amount of the noise figure. An example of the relationship between the gain suppression amount and the degradation amount of the G / T ratio is shown in Fig. 11. The horizontal axis of Fig. 11 represents the gain suppression amount (unit: dB), and the vertical axis represents the degradation amount of the G / T ratio (unit: dB).

[0051] 6, the gain suppression amount determination unit 22 determines whether or not there is a gain suppression amount that brings the degradation amount of the G / T ratio into the target range (step S15). If the gain suppression amount determination unit 22 determines that there is no gain suppression amount that brings the degradation amount of the G / T ratio into the target range (step S15; No), the element control unit 23 controls the antenna elements 11 to adjust the ratio of the number of antenna elements 11 operating as primary polarization elements to the total number of antenna elements 11 (step S16). As an example, the element control unit 23 controls one of the antenna elements 11 operating as a primary polarization element to operate it as a cross polarization element.

[0052] If the gain suppression amount determiner 22 determines that there is a gain suppression amount that brings the G / T ratio degradation amount into the target range (step S15; Yes), it selects one of the gain suppression amounts that brings the G / T ratio degradation amount into the target range (step S17). As an example, the gain suppression amount determiner 22 selects a gain suppression amount that brings the G / T ratio degradation amount into the minimum value. As another example, the gain suppression amount determiner 22 selects a gain suppression amount that corresponds to a range where the G / T ratio degradation amount is equal to or greater than the minimum value and equal to or less than the minimum value plus 0.1 dB. The target range of the G / T ratio degradation amount may be determined according to the communication quality required for the receiving device 1. The gain suppression amount determiner 22 supplies the selected gain suppression amount to the gain adjuster 14a corresponding to the antenna element 11a operating as the main polarization element. After completing step S17, the control unit 20 included in the receiving device 1 terminates the gain suppression amount determination process.

[0053] Once the gain suppression amount is determined as described above, the control unit 20 included in the receiving device 1 shown in FIG. 1 calculates a phase adjustment amount. Specifically, the phase detection unit 24 detects the phase of the combined signal. The phase adjustment amount determiner 25 calculates, from the phase detected by the phase detection unit 24, a phase adjustment amount for adjusting the phase of the received signal output by the gain adjuster 14b corresponding to the antenna element 11b to the opposite phase of the cross-polarized component included in the received signal output by the gain adjuster 14a corresponding to the antenna element 11a. The phase adjustment amount may be any value included in a phase target range that includes a phase target value for adjusting the phase of the received signal output by the gain adjuster 14b corresponding to the antenna element 11b to the opposite phase of the cross-polarized component included in the received signal output by the gain adjuster 14a corresponding to the antenna element 11a. For example, the phase target range is a range of ±15° of the phase target value. The phase adjustment amount determiner 25 stores the calculated phase adjustment amount in the memory 82 and supplies it to the phase shifter 13b corresponding to the antenna element 11b.

[0054] As described above, the gain suppression amount determiner 22 included in the receiving device 1 according to the embodiment determines a gain suppression amount that brings the amplitude of the cross-polarized component included in the received signal generated by the antenna element 11a operating as the primary polarization element closer to the amplitude of the received signal generated by the antenna element 11b operating as the cross-polarized element, within a range in which the degradation of the figure of merit G / T ratio falls within a target range. The gain adjuster 14a included in the receiving device 1 adjusts a predetermined gain according to the gain suppression amount determined as described above, and adjusts the amplitude of the received signal generated by the antenna element 11a operating as the primary polarization element based on the adjusted gain. As a result, the amplitude of the cross-polarized component included in the received signal generated by the antenna element 11a approaches the amplitude of the received signal generated by the antenna element 11b operating as the cross-polarized element.

[0055] The phase adjustment amount determiner 25 included in the receiving device 1 determines a phase adjustment amount for making the phase of the received signal generated by the antenna element 11b operating as a cross-polarized element the opposite phase of the cross-polarized component contained in the received signal generated by the antenna element 11a operating as a main polarization element. The phase shifter 13b adjusts the determined phase shift amount in accordance with the phase adjustment amount calculated as described above, and adjusts the phase of the received signal generated by the antenna element 11b based on the adjusted phase shift amount.

[0056] By combining the received signals in the combining circuit 15, the cross-polarized component contained in the received signal generated by the antenna element 11a and the received signal generated by the antenna element 11b cancel each other out, thereby achieving a receiving device 1 with high communication quality.

[0057] The present disclosure is not limited to the above-described embodiment. The receiving device 1 may receive not only linearly polarized waves but also circularly polarized waves. Fig. 12 shows an example of a receiving device 2 that receives circularly polarized waves including a main polarization component and a cross polarization component. As one example, in a receiving device 2 that is intended to receive right-handed circularly polarized waves, the main polarization component is right-handed circularly polarized waves and the cross polarization component is left-handed circularly polarized waves. As another example, in a receiving device 2 that is intended to receive left-handed circularly polarized waves, the main polarization component is left-handed circularly polarized waves and the cross polarization component is right-handed circularly polarized waves.

[0058] The receiving device 2 comprises a plurality of antenna elements 31 that operate as main polarization elements or cross polarization elements, receive radio waves, and generate received signals, an antenna unit 10 that adjusts the phase and amplitude of the received signals and outputs a composite signal, and a control unit 20 that controls each part of the receiving device 2 described above.

[0059] The antenna unit 10 includes a plurality of low-noise amplifiers 12 that amplify the received signals, a plurality of phase shifters 13 that adjust the phase of the received signals, a plurality of gain adjusters 14 that adjust the amplitude of the received signals, and a combining circuit 15 that combines the received signals.

[0060] Two low-noise amplifiers 12, two phase shifters 13, and two gain adjusters 14 are provided corresponding to each antenna element 31. As in Fig. 1, the antenna elements 31 operating as main polarization elements are designated as antenna elements 31a, and the antenna elements 31 operating as cross polarization elements are designated as antenna elements 31b. The arrangement of the antenna elements 31 is the same as the arrangement of the antenna elements 11 shown in Figs. 2 to 4.

[0061] A circular patch antenna is equipped with a port for receiving vertically polarized waves and a port for receiving horizontally polarized waves, and by creating a 90-degree phase difference between the vertically polarized waves and the horizontally polarized waves, right-handed circular polarization is obtained, and by creating a -90-degree phase difference between the vertically polarized waves and the horizontally polarized waves, left-handed circular polarization is obtained.

[0062] Of the two low-noise amplifiers 12 associated with the same antenna element 31a, the low-noise amplifier 12 that amplifies the vertical component of the received signal is referred to as low-noise amplifier 121a, and the low-noise amplifier 12 that amplifies the horizontal component of the received signal is referred to as low-noise amplifier 122a. Of the two low-noise amplifiers 12 associated with the same antenna element 31b, the low-noise amplifier 12 that amplifies the vertical component of the received signal is referred to as low-noise amplifier 121b, and the low-noise amplifier 12 that amplifies the horizontal component of the received signal is referred to as low-noise amplifier 122b. The operation of the low-noise amplifiers 121a and 122a is the same as that of the low-noise amplifier 12a. The operation of the low-noise amplifiers 121b and 122b is the same as that of the low-noise amplifier 12b.

[0063] Of the two phase shifters 13 associated with the same antenna element 31a, the phase shifter 13 that adjusts the phase of the vertical component of the received signal will be referred to as phase shifter 131a, and the phase shifter 13 that adjusts the phase of the horizontal component of the received signal will be referred to as phase shifter 132a. Of the two phase shifters 13 associated with the same antenna element 31b, the phase shifter 13 that adjusts the phase of the vertical component of the received signal will be referred to as phase shifter 131b, and the phase shifter 13 that adjusts the phase of the horizontal component of the received signal will be referred to as phase shifter 132b. The operation of phase shifters 131a and 132a is the same as that of phase shifter 13a. The operation of phase shifters 131b and 132b is the same as that of phase shifter 13b. As an example, when right-handed circularly polarized waves are the main polarization components, the phase shift amount that will result in a phase difference of 90 degrees between the outputs of phase shifters 131a and 132a is set in advance in phase shifters 131a and 132a, and the phase shift amount that will result in a phase difference of -90 degrees between the outputs of phase shifters 131b and 132b is set in advance in phase shifters 131b and 132b.

[0064] Of the two gain adjusters 14 associated with the same antenna element 31a, the gain adjuster 14 that adjusts the amplitude of the vertical component of the received signal will be referred to as gain adjuster 141a, and the gain adjuster 14 that adjusts the amplitude of the horizontal component of the received signal will be referred to as gain adjuster 142a. Of the two gain adjusters 14 associated with the same antenna element 31b, the gain adjuster 14 that adjusts the amplitude of the vertical component of the received signal will be referred to as gain adjuster 141b, and the gain adjuster 14 that adjusts the amplitude of the horizontal component of the received signal will be referred to as gain adjuster 142b. The operation of the gain adjusters 141a and 142a is similar to that of the gain adjuster 14a. The operation of the gain adjusters 141b and 142b is similar to that of the gain adjuster 14b.

[0065] The vertical component of the received signal generated by antenna element 31a operating as the main polarization element is amplified by low-noise amplifier 121a, its phase is adjusted by phase shifter 131a, its amplitude is adjusted by gain adjuster 141a, and then supplied to combining circuit 15. The horizontal component of the received signal generated by antenna element 31a operating as the main polarization element is amplified by low-noise amplifier 122a, its phase is adjusted by phase shifter 132a, its amplitude is adjusted by gain adjuster 142a, and then supplied to combining circuit 15.

[0066] The vertical component of the received signal generated by antenna element 31b operating as a cross-polarized element is amplified by low-noise amplifier 121b, has its phase adjusted by phase shifter 131b, its amplitude adjusted by gain adjuster 141b, and is supplied to combining circuit 15. The horizontal component of the received signal generated by antenna element 31b operating as a cross-polarized element is amplified by low-noise amplifier 122b, has its phase adjusted by phase shifter 132b, its amplitude adjusted by gain adjuster 142b, and is supplied to combining circuit 15.

[0067] The operation of the control unit 20 provided in the receiving device 2 is the same as the operation performed by the control unit 20 provided in the receiving device 1. The amplitude detection unit 21 detects the amplitudes of the main polarization component and the cross polarization component from the result of combining the outputs of the gain adjusters 141a and 142a. The phase adjustment amount determination unit 25 determines the phase adjustment amount from the result of combining the outputs of the gain adjusters 141a and 142a. As described above, even in the receiving device 2 that receives circularly polarized waves, the cross polarization component included in the received signal generated by the antenna element 31a operating as the main polarization element is canceled out, resulting in a receiving device 2 with high communication quality.

[0068] The receiving device according to the embodiment of the present disclosure is not limited to receiving linearly polarized waves, but may also receive obliquely polarized waves. Also, the receiving device according to the embodiment of the present disclosure may be used in a satellite communication system including, for example, an antenna, a transceiver, a frequency converter, a modem, and a controller.

[0069] The arrangement method of the antenna elements 11 and 31 is not limited to the above example, and any arrangement method can be used as long as it can suppress the occurrence of grating lobes. As an example, the antenna element 11b may be arranged along each side of the arrangement area 101. In this way, the antenna elements 11a are arranged in a rectangular shape, thereby suppressing the occurrence of grating lobes. Furthermore, the shape of the arrangement area 101 is not limited to a rectangle, and may be any shape. In a circular or elliptical arrangement area 101, the antenna element 11b may be arranged along the boundary. In this way, the antenna elements 11a are arranged in a circular or elliptical shape, thereby suppressing the occurrence of grating lobes.

[0070] The configuration of the receiving devices 1 and 2 is not limited to the above example. As an example, the connection order of the low-noise amplifier 12, the phase shifter 13, and the gain adjuster 14 may be reversed in the receiving devices 1 and 2. For example, the received signal generated by the antenna elements 11 and 31 may be amplified by the low-noise amplifier 12, the amplitude may be adjusted by the gain adjuster 14, and then the phase may be adjusted by the phase shifter 13.

[0071] As another example, the receiving device according to the embodiment of the present disclosure does not need to include the low noise amplifier 12 .

[0072] As another example, the gain adjusters 14 a and 14 b may each include an amplifier with a fixed gain and a variable attenuator with an adjustable attenuation amount. The amplifier amplifies the input received signal and supplies the amplified signal to the variable attenuator. The variable attenuator attenuates the received signal amplified by the amplifier in accordance with the gain suppression amount supplied from the control unit 20.

[0073] Cross-polarization discrimination γ ０ is not limited to the maximum value of the amplitude difference between the main polarization component and the cross polarization component obtained for each scan angle. As an example, the amplitude difference between the main polarization component and the cross polarization component detected by the amplitude detector 21 is obtained for each scan angle, and the obtained amplitude difference is used as the cross polarization discrimination factor γ ０ In this case, the element control unit 23 controls the antenna elements 11 in a range in which the deterioration of the figure of merit falls within a target range according to the scan angle, and adjusts the ratio of the number of antenna elements 11 operating as primary polarization elements to the total number of antenna elements 11. The same applies to the antenna element 31.

[0074] The configuration of the receiving devices 1 and 2 is not limited to the above example. As an example, the received signals may be converted from analog to digital, and a combined signal may be generated by the control unit 20. In detail, the received signals generated by the antenna elements 11 and 31 are amplified by the low-noise amplifier 12, their phases adjusted by the phase shifter 13, their amplitudes adjusted by the gain adjuster 14, converted into digital received signals by the analog-to-digital converter, and transmitted to the control unit 20. The control unit 20 combines the received digital received signals to generate a combined signal.

[0075] The above hardware configuration is one example, and can be changed and modified as desired. As another example of the hardware configuration, a modified hardware configuration of the control unit 20 provided in the receiving devices 1 and 2 is shown in Fig. 13. The control unit 20 may be realized by a processing circuit 84, as shown in Fig. 13. The processing circuit 84 provided in the control unit 20 shown in Fig. 13 is connected to the antenna unit 10 via an interface circuit 85.

[0076] When the processing circuitry 84 is dedicated hardware, the processing circuitry 84 includes, for example, a single circuit, a composite circuit, a processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. Each unit of the control unit 20 may be realized by an individual processing circuit 84, or each unit of the control unit 20 may be realized by a common processing circuit 84.

[0077] Some of the functions of the control unit 20 may be realized by dedicated hardware, and other parts may be realized by software or firmware. For example, in the control unit 20, the amplitude detection unit 21, the phase detection unit 24, and the element control unit 23 may be realized by a processing circuit 84 shown in Fig. 13, and the gain suppression amount determination unit 22 and the phase adjustment amount determination unit 25 may be realized by a processor 81 shown in Fig. 5 reading and executing a program stored in a memory 82. Furthermore, all of the functions of the control unit 20 may be realized by software or firmware.

[0078] Various aspects of the present disclosure are collectively described below as appendices. (Appendix 1) A receiving device for receiving radio waves including a primary polarization component and a cross polarization component that crosses the primary polarization component, comprising: a plurality of antenna elements that operate as primary polarization elements that receive the primary polarization component or cross polarization elements that receive the cross polarization component, and receive the radio waves to generate received signals; a plurality of phase shifters that are provided in correspondence with the antenna elements, and that adjust the phase of the received signal generated by the corresponding antenna element based on a predetermined phase shift amount when the corresponding antenna element operates as the primary polarization element, and adjust the predetermined phase shift amount in accordance with a phase adjustment amount when the corresponding antenna element operates as the cross polarization element, and adjust the phase of the received signal generated by the corresponding antenna element based on the adjusted phase shift amount; a plurality of gain adjusters provided in correspondence with the antenna elements, the adjusters adjusting a predetermined gain in accordance with a gain suppression amount when the corresponding antenna element operates as the main polarization element, and adjusting the amplitude of the reception signal generated by the corresponding antenna element based on the adjusted gain, and adjusting the amplitude of the reception signal generated by the corresponding antenna element based on the predetermined gain when the corresponding antenna element operates as the cross polarization element; and a combining circuit combining the reception signals whose phases have been adjusted by the phase shifters and whose amplitudes have been adjusted by the gain adjusters, wherein the gain suppression amount is a gain suppression amount that brings the amplitude of the cross polarization component included in the reception signal generated by the antenna element operating as the main polarization element closer to the amplitude of the reception signal generated by the antenna element operating as the cross polarization element, within a range in which a deterioration amount of a figure of merit indicating communication quality of the receiving device is within a target range, A receiving device, wherein the phase adjustment amount is a phase adjustment amount that makes the phase of the received signal generated by the antenna element operating as the cross-polarized element opposite to the phase of the cross-polarized component contained in the received signal generated by the antenna element operating as the main polarization element.(Supplementary Note 2) The receiving device according to Supplementary Note 1, wherein the receiving device uses a G / T (Gain to Noise Temperature) ratio as the figure of merit, and calculates the amount of gain suppression from the relationship between the amount of gain suppression and the amount of degradation of the G / T ratio, within a range in which the amount of degradation of the G / T ratio is included in the target range. (Supplementary Note 3) The receiving device according to Supplementary Note 2, wherein the receiving device calculates the amount of gain suppression from the relationship between the amount of gain suppression and the amount of degradation of the G / T ratio, which is obtained from the relationship between the amount of gain suppression and an amount of reduction in antenna gain of the receiving device and the relationship between the amount of gain suppression and an amount of degradation of a noise figure. (Supplementary Note 4) The receiving device according to Supplementary Note 2, wherein the receiving device calculates the amount of gain suppression so that the amount of degradation of the G / T ratio is equal to or greater than a minimum value of the amount of degradation of the G / T ratio and is equal to or less than a value obtained by adding 0.1 dB to the minimum value of the amount of degradation of the G / T ratio. (Supplementary Note 5) The receiving device according to any one of Supplementary Notes 1 to 4, further comprising an element control unit that determines the number of each of the main polarization elements and the cross polarization elements within a range in which a degradation amount of the figure of merit falls within the target range, and controls each of the antenna elements based on the determined numbers of each of the main polarization elements and the cross polarization elements to operate as the main polarization element or the cross polarization element. (Supplementary Note 6) The receiving device according to Supplementary Note 5, wherein the element control unit determines the number of each of the main polarization elements and the cross polarization elements for each scan angle, and controls the antenna elements to achieve the determined numbers of each of the main polarization elements and the cross polarization elements according to the scan angle. (Supplementary Note 7) The receiving device according to any one of Supplementary Notes 1 to 6, further comprising: a gain suppression amount determiner that supplies the gain suppression amount to the gain adjuster corresponding to the antenna element operating as the main polarization element; and a phase adjustment amount determiner that supplies the phase adjustment amount to the phase shifter corresponding to the antenna element operating as the cross polarization element. (Supplementary Note 8) The receiving device according to any one of Supplementary Notes 1 to 7, wherein the antenna elements receive the radio waves that are linearly polarized waves to generate the received signals, the phase shifter is provided for each of the antenna elements, and the gain adjuster is provided for each of the antenna elements.(Supplementary Note 9) The receiving device according to any one of Supplementary Notes 1 to 7, wherein the antenna elements receive the radio waves which are circularly polarized waves and generate the received signal, wherein two of the phase shifters are provided corresponding to each of the antenna elements, wherein two of the gain adjusters are provided corresponding to each of the antenna elements, wherein one of the two phase shifters associated with the same antenna element adjusts the phase of a horizontal component of the received signal and the other adjusts the phase of a vertical component of the received signal, and wherein one of the two gain adjusters associated with the same antenna element adjusts the amplitude of the horizontal component of the received signal and the other adjusts the amplitude of the vertical component of the received signal. (Supplementary Note 10) The receiving device according to any one of Supplementary Notes 1 to 9, wherein the plurality of antenna elements are arranged at equal intervals in a predetermined arrangement area on a substrate, and at least one of the antenna elements arranged adjacent to a boundary line of the arrangement area operates as the cross-polarized element. (Supplementary Note 11) The receiving device according to Supplementary Note 10, wherein the placement area has a rectangular shape, and at least one of the antenna elements placed adjacent to at least one side of the rectangle operates as the cross-polarized element. (Supplementary Note 12) The receiving device according to Supplementary Note 10, wherein the placement area has a rectangular shape, and at least one of the antenna elements placed adjacent to each vertex of the rectangle operates as the cross-polarized element. (Supplementary Note 13) The receiving device according to any of Supplements 1 to 9, wherein the plurality of antenna elements are placed at equal intervals in a predetermined placement area on a substrate, and among the plurality of antenna elements operating as the cross-polarized elements, the interval between adjacent antenna elements is equal to or greater than a threshold determined in accordance with the respective numbers of the main polarization elements and the cross-polarized elements.

[0079] The present disclosure allows various embodiments and modifications without departing from the broad spirit and scope of the present disclosure. Furthermore, the above-described embodiments are intended to illustrate the present disclosure and do not limit the scope of the present disclosure. That is, the scope of the present disclosure is defined by the claims, not the embodiments. Various modifications made within the scope of the claims and the meaning of equivalent disclosures are considered to be within the scope of the present disclosure.

[0080] This application is based on Japanese Patent Application No. 2024-148651, filed on August 30, 2024. The entire specification, claims, and drawings of Japanese Patent Application No. 2024-148651 are incorporated herein by reference.

[0081] 1, 2 receiving device, 10 antenna unit, 11, 11a, 11b, 31, 31a, 31b antenna elements, 12, 12a, 12b, 121a, 121b, 122a, 122b low noise amplifiers, 13, 13a, 13b, 131a, 131b, 132a, 132b phase shifters, 14, 14a, 14b, 141a, 141b, 142a, 142b gain adjusters, 15 combining circuit, 20 control unit, 21 amplitude detection unit, 22 gain suppression amount determination unit, 23 element control unit, 24 phase detection unit, 25 phase adjustment amount determination unit, 80 bus, 81 processor, 82 memory, 83 interface, 84 processing circuit, 85 interface circuit, 100 substrate, 101 placement area.

Claims

1. A receiving device for receiving radio waves including a primary polarization component and a cross polarization component that crosses the primary polarization component, comprising: a plurality of antenna elements that operate as primary polarization elements that receive the primary polarization component or cross polarization elements that receive the cross polarization component, and that receive the radio waves and generate received signals; and a plurality of phase shifters that are provided in correspondence with the antenna elements, and that, when the corresponding antenna element operates as the primary polarization element, adjust the phase of the received signal generated by the corresponding antenna element based on a predetermined phase shift amount, and, when the corresponding antenna element operates as the cross polarization element, adjust the predetermined phase shift amount in accordance with a phase adjustment amount, and adjust the phase of the received signal generated by the corresponding antenna element based on the adjusted phase shift amount. a plurality of gain adjusters provided in correspondence with the antenna elements, the adjusters adjusting a predetermined gain in accordance with a gain suppression amount when the corresponding antenna element operates as the main polarization element, and adjusting the amplitude of the reception signal generated by the corresponding antenna element based on the adjusted gain, and adjusting the amplitude of the reception signal generated by the corresponding antenna element based on the predetermined gain when the corresponding antenna element operates as the cross polarization element; and a combining circuit combining the reception signals whose phases have been adjusted by the phase shifters and whose amplitudes have been adjusted by the gain adjusters, wherein the gain suppression amount is a gain suppression amount that brings the amplitude of the cross polarization component included in the reception signal generated by the antenna element operating as the main polarization element closer to the amplitude of the reception signal generated by the antenna element operating as the cross polarization element, within a range in which a deterioration amount of a figure of merit indicating communication quality of the receiving device is within a target range, A receiving device, wherein the phase adjustment amount is a phase adjustment amount that makes the phase of the received signal generated by the antenna element operating as the cross-polarized element opposite to the phase of the cross-polarized component contained in the received signal generated by the antenna element operating as the main polarization element.

2. The receiving device according to claim 1, wherein the receiving device uses a G / T (Gain to Noise Temperature) ratio as the performance index, and calculates the amount of gain suppression from the relationship between the amount of gain suppression and the amount of deterioration of the G / T ratio within a range in which the amount of deterioration of the G / T ratio is included in the target range.

3. The receiving device according to claim 2, wherein the receiving device determines the amount of gain suppression within a range in which the amount of degradation of the G / T ratio is included in the target range, based on the relationship between the amount of gain suppression and the amount of reduction in antenna gain of the receiving device and the relationship between the amount of gain suppression and the amount of degradation of the G / T ratio, which is obtained from the relationship between the amount of gain suppression and the amount of degradation of the noise figure.

4. The receiving device according to claim 2, wherein the receiving device calculates the gain suppression amount in a range where the deterioration amount of the G / T ratio is equal to or greater than the minimum value of the deterioration amount of the G / T ratio and is equal to or less than the minimum value of the deterioration amount of the G / T ratio plus 0.1 dB.

5. A receiving device as described in any one of claims 1 to 4, further comprising an element control unit that determines the number of each of the main polarization elements and the cross polarization elements within a range in which the deterioration amount of the figure of merit falls within the target range, and controls each of the antenna elements based on the determined number of each of the main polarization elements and the cross polarization elements to operate as the main polarization element or the cross polarization element.

6. The receiving device according to claim 5, wherein the element control unit determines the number of main polarization elements and cross polarization elements for each scanning angle, and controls the antenna elements so that the determined numbers of main polarization elements and cross polarization elements are achieved according to the scanning angle.

7. A receiving device as claimed in any one of claims 1 to 6, further comprising: a gain suppression amount determination unit that supplies the gain suppression amount to the gain adjuster corresponding to the antenna element operating as the main polarization element; and a phase adjustment amount determination unit that supplies the phase adjustment amount to the phase shifter corresponding to the antenna element operating as the cross polarization element.

8. A receiving device according to any one of claims 1 to 7, wherein the antenna elements receive the radio waves which are linearly polarized waves to generate the received signals, the phase shifter is provided for each of the antenna elements, and the gain adjuster is provided for each of the antenna elements.

9. A receiving device as claimed in any one of claims 1 to 7, wherein the antenna elements receive the radio waves which are circularly polarized waves and generate the received signal, two phase shifters are provided corresponding to each of the antenna elements, two gain adjusters are provided corresponding to each of the antenna elements, one of the two phase shifters associated with the same antenna element adjusts the phase of the vertical component of the received signal, and the other adjusts the phase of the horizontal component of the received signal, and one of the two gain adjusters associated with the same antenna element adjusts the amplitude of the vertical component of the received signal, and the other adjusts the amplitude of the horizontal component of the received signal.

10. A receiving device as claimed in any one of claims 1 to 9, wherein the plurality of antenna elements are arranged at equal intervals in a defined arrangement area on a substrate, and at least one of the antenna elements arranged adjacent to the boundary line of the arrangement area operates as the cross-polarized element.

11. The receiving device according to claim 10, wherein the arrangement area has a rectangular shape, and at least one of the antenna elements arranged adjacent to at least one side of the rectangle operates as the cross-polarized element.

12. The receiving device according to claim 10, wherein the arrangement area has a rectangular shape, and at least one of the antenna elements arranged adjacent to each vertex of the rectangle operates as the cross-polarized element.

13. A receiving device as described in any one of claims 1 to 9, wherein the plurality of antenna elements are arranged at equal intervals in a predetermined arrangement area on a substrate, and among the plurality of antenna elements operating as the cross-polarized elements, the interval between adjacent antenna elements is equal to or greater than a threshold determined according to the respective numbers of the main polarization elements and the cross-polarized elements.

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