Electronically scanned antenna system and communication method

Abstract

The present invention provides an electronically scanned antenna system capable of continuous communication with a communication device. An electronic scanning antenna system (1) is an electronic scanning antenna system capable of communicating with a communication device (2). The electronically scanned antenna system includes a plurality of elements E1-E17 capable of receiving a reception signal transmitted from a communication device, a plurality of communication paths R1-R17 connected to the plurality of elements, respectively, and a communication unit 121 capable of communicating with the communication device via each of the plurality of elements and each of the plurality of communication paths. The plurality of communication paths include a first path and a second path different from the first path. The communication unit includes a receiving unit 121R that receives a reception signal from the communication device via each of the first path and the second path, and a transmitting unit 121T that transmits a transmission signal received by the communication device to the communication device via only one of the first path and the second path.

Description

[Technical Field]

[0001] The present invention relates to an electronically scanned antenna system and method of communication. [Background technology]

[0002] Conventionally, an electronically scanned antenna system (hereinafter referred to as a "conventional antenna") capable of communicating with a communication device (base station) has been known (see, for example, Patent Document 1). The conventional antenna includes, for example, a plurality of elements, a plurality of communication paths, and a communication unit. Each of the plurality of elements is capable of receiving a predetermined signal transmitted from the communication device. Each of the plurality of communication paths is connected to a corresponding element and communication unit. The communication unit receives a predetermined signal (hereinafter referred to as a "received signal") from the communication device via each of the plurality of elements and each of the plurality of communication paths, and transmits a predetermined signal (hereinafter referred to as a "transmitted signal") to the communication device. The conventional antenna communicates (transmits and receives) with the communication device, for example, only via a communication path (hereinafter referred to as a "first path") through which a received signal having the highest signal level among the received signals received by each of the plurality of elements is transmitted.

[0003] Here, when the relative positional relationship between the conventional antenna and the communication device changes, the signal level of the received signal transmitted via the first path (hereinafter referred to as the "first signal level") changes. If the changed signal level is smaller than a predetermined threshold, communication via the first path is disconnected, and the communication unit cannot communicate with the communication device via the first path. At this time, the conventional antenna searches for a communication path (hereinafter referred to as the "second path") through which a received signal having a signal level equal to or greater than the predetermined threshold is transmitted, and establishes communication via that communication path. The communication unit communicates (transmits and receives) with the communication device only via the second path. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-178051 Summary of the Invention [Problem to be solved by the invention]

[0005] However, there is a period of time between when communication via the first path is disconnected and when communication via the second path is established, i.e., a period of time during which the conventional antenna cannot communicate with the communication device. During this period of time, the communication unit cannot receive incoming signals from the communication device and cannot transmit outgoing signals to the communication device. In other words, the conventional antenna cannot continuously communicate (transmit and receive) with the communication device. In this case, the amount of signal (amount of data) per unit time that the conventional antenna can communicate (transmit and receive) with the communication device decreases due to an increase in the time required for signal processing (e.g., signal capture and decoding) and a decrease in downlink time (time during which a signal is transmitted).

[0006] Therefore, there is a demand for an electronically scanned antenna system that can communicate continuously with a communication device even when the relative positional relationship with the communication device changes.

[0007] An object of the present invention is to provide an electronically scanned antenna system and a communication method that are capable of communicating with a communication device continuously even when the relative positional relationship with the communication device changes. [Means for solving the problem]

[0008] The electronic scanning antenna system of the present invention is an electronic scanning antenna system capable of communicating with a communication device, and comprises a plurality of elements capable of receiving a received signal transmitted from the communication device, a plurality of communication paths connected to each of the plurality of elements, and a communication unit capable of communicating with the communication device via each of the plurality of elements and each of the plurality of communication paths, wherein the plurality of communication paths include a first path and a second path different from the first path, and the communication unit comprises a receiving unit that receives a received signal from the communication device via each of the first path and the second path, and a transmitting unit that transmits a transmitted signal received by the communication device to the communication device via only one of the first path and the second path. [Effects of the Invention]

[0009] The present invention can provide an electronically scanned antenna system and a communication method that can continuously communicate with a communication device even when the relative positional relationship with the communication device changes. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a network configuration diagram of an electronically scanned antenna system according to an embodiment of the present invention; [Figure 2] 2A and 2B are a schematic perspective view and a schematic plan view of the electronic scanning antenna system of FIG. 1; [Figure 3] FIG. 2 is a functional block diagram of the electronically scanned antenna system of FIG. 1. [Figure 4] 2A and 2B are a schematic front view and a schematic plan view of the electronic scanning antenna system of FIG. 1. [Figure 5] 1 is a flowchart illustrating an embodiment of a communication method according to the present invention. [Figure 6] 2A and 2B are a schematic front view and a schematic plan view of the electronically scanned antenna system of FIG. 1, showing an example of the operation of the antenna system. [Figure 7] 2 is a functional block diagram of the electronically scanned antenna system of FIG. 1, illustrating an example of the operation of the antenna system. [Figure 8] 2 is a schematic front view of the electronically scanned antenna system of FIG. 1, illustrating an example of the operation of the antenna system. FIG. [Figure 9] 2 is a functional block diagram of the electronically scanned antenna system of FIG. 1, illustrating an example of the operation of the antenna system. [Figure 10] 2 is a schematic front view of the electronically scanned antenna system of FIG. 1, illustrating an example of the operation of the antenna system. FIG. [Figure 11] 2 is a functional block diagram of the electronically scanned antenna system of FIG. 1, illustrating an example of the operation of the antenna system. [Figure 12] 2 is a schematic front view of the electronically scanned antenna system of FIG. 1, illustrating an example of the operation of the antenna system. FIG. [Figure 13]2 is a functional block diagram of the electronically scanned antenna system of FIG. 1, illustrating an example of the operation of the antenna system. [Figure 14] 2 is a schematic front view of the electronically scanned antenna system of FIG. 1, illustrating an example of the operation of the antenna system. FIG. [Figure 15] 2 is a functional block diagram of the electronically scanned antenna system of FIG. 1, illustrating an example of the operation of the antenna system. [Figure 16] 2 is a schematic front view of the electronically scanned antenna system of FIG. 1, illustrating an example of the operation of the antenna system. FIG. [Figure 17] 2 is a functional block diagram of the electronically scanned antenna system of FIG. 1, illustrating an example of the operation of the antenna system. [Figure 18] 2 is a schematic front view of the electronically scanned antenna system of FIG. 1, showing another example of the operation of the antenna system. FIG. [Figure 19] 2 is a functional block diagram of the electronically scanned antenna system of FIG. 1, illustrating another example of the operation of the antenna system. [Figure 20] FIG. 10 is a functional block diagram of a modified example of the electronically scanned antenna system according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Embodiments of an electronically scanned antenna system (hereinafter referred to as "the antenna") according to the present invention and a communication method (hereinafter referred to as "the method") according to the present invention will be described below with reference to the drawings. In each drawing, the same members and elements are designated by the same reference numerals, and duplicated explanations will be omitted. Furthermore, the dimensional proportions of each element may be exaggerated for the sake of convenience, and are not limited to the proportions shown in each drawing.

[0012] ●Embodiment of this antenna● ●Configuration of this antenna The configuration of this antenna is described below.

[0013] FIG. 1 is a network configuration diagram of the present antenna, showing an embodiment of the present antenna.

[0014] The antenna 1 is an electronically scanned antenna system capable of communicating with a communication device 2. The antenna 1 is connected to the communication device 2 via a communication line L. The antenna 1 is installed on a lunar rover (not shown) that travels on the surface of the moon. In other words, the antenna 1 is installed on the surface of the moon.

[0015] The communication device 2 is an artificial satellite that can communicate with the antenna 1. The communication device 2 is connected to the antenna 1 via a communication line L. The communication device 2 orbits the moon.

[0016] The communication line L is a wireless communication line that connects the antenna 1 and the communication device 2.

[0017] 2A and 2B are a schematic perspective view and a schematic plan view of the antenna 1. Specifically, (a) is a schematic perspective view of the antenna 1, and (b) is a schematic plan view of the antenna 1.

[0018] 3 is a functional block diagram of the antenna 1. In the figure, for the sake of convenience, the communication device 2 and the communication line L are both shown.

[0019] The antenna 1 includes a housing 11, a plurality (17) of elements E1, E2, E3, E4, E5, E6, E7, E8, E9, E10, E11, E12, E13, E14, E15, E16, and E17, a plurality (17) of communication paths R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, R16, and R17, a plurality (17) of switches SW1, SW2, SW3, SW4, SW5, SW6, SW7, SW8, SW9, SW10, SW11, SW12, SW13, SW14, SW15, SW16, and SW17, and a control unit 12.

[0020] In the following description, when elements E1 to E17 are not particularly distinguished from one another, they are collectively referred to as "element E." When communication paths R1 to R17 are not particularly distinguished from one another, they are collectively referred to as "communication path R." When switches SW1 to SW17 are not particularly distinguished from one another, they are collectively referred to as "switch SW."

[0021] The housing 11 houses the communication path R, the switch SW, and the control unit 12. The housing 11 has a plurality of (18) surfaces, specifically, an upper surface 111 facing upward, a lower surface 112 facing downward, a plurality of (8) side surfaces 113 perpendicular to the upper surface 111, and a plurality of (8) inclined surfaces 114 disposed between the upper surface 111 and each of the plurality of side surfaces 113. The inclined surfaces 114 are inclined at an angle of 45° with respect to the upper surface 111, the lower surface 112, and the side surfaces 113. The housing 11 is a polyhedron (octahedron) and has a regular octagonal shape when viewed from above.

[0022] The "upward direction" is the direction in which the upper surface 111 is disposed relative to the lower surface 112. The "downward direction" is the opposite direction to the upward direction.

[0023] Element E is capable of receiving a signal transmitted from communication device 2. Element E is a planar patch antenna element. Of the multiple (18) surfaces of housing 11, elements E are arranged on top surface 111, side surface 113, and inclined surface 114, excluding bottom surface 112, and are oriented in different directions. One element E corresponds to one surface (top surface 111, side surface 113, inclined surface 114). That is, elements E1 to E8 are arranged on the corresponding side surface 113, elements E9 to E16 are arranged on the corresponding inclined surface 114, and element E17 is arranged on top surface 111. The surface of element E1 is oriented upward. That is, top surface 111, multiple (8) side surfaces 113, and multiple (8) inclined surfaces 114 are surfaces (corresponding surfaces) corresponding to element E. The corresponding surfaces form a polyhedron (a heptahedron) that has a regular octagonal shape when viewed from above. The surfaces of elements E9 to E16 are inclined at an angle of 45° relative to the surfaces of elements E1 to E8 and E17. The surfaces of elements E1 to E8 are perpendicular to the surface of element E17. In this way, elements E form a polyhedron antenna. Details of received signals will be described later.

[0024] Element E1 is adjacent to elements E2, E8, and E9. Element E2 is adjacent to elements E1, E3, and E10. Element E3 is adjacent to elements E2, E4, and E11. Element E4 is adjacent to elements E3, E5, and E12. Element E5 is adjacent to elements E4, E6, and E13. Element E6 is adjacent to elements E5, E7, and E14. Element E7 is adjacent to elements E6, E8, and E15. Element E8 is adjacent to elements E7, E9, and E16. Element E9 is adjacent to elements E1, E10, and E16. Element E10 is adjacent to elements E2, E9, and E11. Element E11 is adjacent to elements E3, E10, and E12. Element E12 is adjacent to elements E4, E11, and E13. Element E13 is adjacent to elements E5, E12, and E14. Element E14 is adjacent to elements E6, E13, and E15. Element E15 is adjacent to elements E7, E14, and E16. Element E16 is adjacent to elements E8, E9, and E15. Element E17 is adjacent to elements E9 to E16.

[0025] The communication path R is a path corresponding to the element E. The communication path R is connected to the corresponding element E and the control unit 12 (the demultiplexing / multiplexing unit 124). That is, for example, the communication path R1 corresponds to the element E1 and is connected to the element E1 and the control unit 12.

[0026] Any one of the communication routes R can function as a main route. The "main route" is a route through which received signals and transmitted signals are transmitted.

[0027] Of the communication routes R, any one of the communication routes R other than the communication route R functioning as the main route can function as a sub-route. The "sub-route" is a route through which a received signal is transmitted.

[0028] The communication path R along which the received signal and the transmitted signal are transmitted is an example of the first path in the present invention. The communication path R along which the received signal is transmitted is an example of the second path in the present invention.

[0029] A "received signal" is a signal transmitted from the communication device 2 to the antenna 1 and received by the antenna 1. The received signal is, for example, a signal required to establish communication, a signal indicating the operation or state of the communication device 2, a signal indicating the position of the communication device 2, etc.

[0030] Adjacent elements E among the elements E can simultaneously receive the same reception signal. Note that "simultaneous" does not only mean that the times at which the signals are received by each element E (hereinafter referred to as "reception times") are completely the same (simultaneous), but also includes cases where the reception times are approximately the same, i.e., there is a time lag (for example, delay time due to differences in distance from the communication device 2 to each element E, other communication environments, etc.). Each reception signal received by an element E (reception signal transmitted via communication path R) is a signal indicating a common content.

[0031] In the following description, when the received signals received by elements E1 to E17 (received signals transmitted via communication paths R1 to R17) are to be distinguished from one another, "received signal" is appended with "(1)" to "(17)." That is, for example, the received signal received by element E1 is referred to as "received signal (1)," the received signal received by element E2 is referred to as "received signal (2)," and the received signal received by element E17 is referred to as "received signal (17)."

[0032] The "transmission signal" is a signal transmitted from this antenna 1 to the communication device 2 and received by the communication device 2. The transmission signal is, for example, a signal required to establish a communication line L, a signal indicating the operation or status of the rover, a signal indicating the status of the lunar surface, a signal indicating the position of the rover (this antenna 1), etc.

[0033] In the following description, when the transmission signals transmitted to elements E1 to E17 (transmission signals transmitted via communication paths R1 to R17) are to be distinguished from one another, "transmission signal" is appended with "(1)" to "(17)." That is, for example, the transmission signal transmitted to element E1 is referred to as "transmission signal (1)," the transmission signal transmitted to element E2 is referred to as "transmission signal (2)," and the transmission signal transmitted to element E17 is referred to as "transmission signal (17)."

[0034] The switch SW connects the corresponding element E with the control unit 12 (communication unit 121) to enable communication between the corresponding element E and the control unit 12 (communication unit 121). That is, the switch SW enables a received signal received by the corresponding element E to be transmitted to the communication unit 121 via the corresponding communication path R. The switch SW enables a transmitted signal to the corresponding element E based on the detection result of the level detection unit 122. The switch SW is arranged on the communication path R corresponding to the corresponding element E. Details of the operation of the switch SW will be described later.

[0035] The control unit 12 controls the overall operation of the antenna 1. The control unit 12 includes, for example, a processor (not shown) such as a CPU (Central Processing Unit), a volatile memory (not shown) such as a RAM (Random Access Memory) that functions as a work area for the CPU, and a non-volatile memory (not shown) such as a ROM (Read Only Memory) that stores various information. The "various information" includes, for example, a program that controls the overall operation of the antenna 1, a signal threshold value and a combining threshold value, which will be described later, and the like. The processor functions as a communication unit 121, a level detection unit 122, a path selection unit 123, and a multiplexing / demultiplexing unit 124. That is, the control unit 12 includes the communication unit 121, the level detection unit 122, the path selection unit 123, and the multiplexing / demultiplexing unit 124.

[0036] The communication unit 121 communicates with the communication device 2 via the element E, the communication path R, and the multiplexing / demultiplexing unit 124. The communication unit 121 includes a receiving unit 121R and a transmitting unit 121T.

[0037] The receiver 121R receives a signal from the communication device 2 via two elements E, two communication paths R (a main path and a sub-path), and the multiplexer / demultiplexer .

[0038] The transmitter 121T transmits a transmission signal to the communication device 2 via one element E, one communication path R (main path), and the multiplexer / demultiplexer .

[0039] The level detection unit 122 detects the signal level of the received signal transmitted via the element E, the communication path R, and the multiplexing / demultiplexing unit 124. The signal levels of the received signals received by the element E (the received signals transmitted via the communication path R) differ depending on the relative positional relationship between each element E and the communication device 2. Details of the operation of the level detection unit 122 will be described later.

[0040] In the following description, when the signal levels of the received signals (1) to (17) are to be distinguished, the "signal level" will be prefixed with "(1)" to "(17)." For example, the signal level of received signal (1) will be referred to as "signal level (1)," the signal level of received signal (2) as "signal level (2)," and the signal level of received signal (17) as "signal level (17)."

[0041] The path selection unit 123 selects one of the communication paths R as a main path based on the detection result of the level detection unit 122. The path selection unit 123 selects one of the communication paths R as a sub-path based on the detection result of the level detection unit 122. The path selection unit 123 is an example of a main path selection unit and also an example of a sub-path selection unit in the present invention. Each of the communication unit 121, the level detection unit 122, and the path selection unit 123 is realized by, for example, a software defined radio (SDR). Details of the operation of the path selection unit 123 will be described later.

[0042] The demultiplexing / combining unit 124 transmits to the receiving unit 121R, among the received signals transmitted from the elements E1 to E17 to the demultiplexing / combining unit 124, the received signals transmitted from the elements E connected to the main path and the elements E connected to the sub-path. The demultiplexing / combining unit 124 transmits the transmitted signal transmitted from the transmitting unit 121T to the demultiplexing / combining unit 124 via the main path to the elements E connected to the main path. Based on the detection result of the level detection unit 122, the demultiplexing / combining unit 124 combines multiple received signals having signal levels equal to or greater than a combination threshold and smaller than a signal threshold to generate a combined signal. The demultiplexing / combining unit 124 is connected to the communication path R. Details of the operation of the demultiplexing / combining unit 124 will be described later. The demultiplexing / combining unit 124 is an example of a combiner in the present invention.

[0043] The "signal threshold" is the minimum signal level at which stable communication is possible between the antenna 1 and the communication device 2. In other words, when the antenna 1 receives only signals with signal levels lower than the signal threshold, problems such as an increase in reception time or communication disconnection may occur. In other words, communication between the antenna 1 and the communication device 2 may become unstable. The signal threshold is stored, for example, in a non-volatile memory of the control unit 12.

[0044] The "composite signal" is a signal generated by the multiplexing / demultiplexing unit 124. The composite signal has the same content as that of each of the multiple received signals before being combined. The composite signal is transmitted to the receiving unit 121R and received by the receiving unit 121R. The signal level of the composite signal is equal to or greater than the signal threshold. In other words, the signal level of the composite signal is greater than the signal level of each of the multiple received signals before being combined.

[0045] When the signal levels of the multiple received signals combined by the demultiplexing / combining unit 124 are too low, the signal level of the combined signal generated by the demultiplexing / combining unit 124 is lower than the signal threshold. Therefore, the signal levels of the multiple received signals combined by the demultiplexing / combining unit 124 must be equal to or higher than a predetermined value (combining threshold). In other words, the "combining threshold" is the minimum signal level of the received signals that are the basis of the combined signal having a signal level equal to or higher than the signal threshold. When the signal levels of the multiple received signals combined by the demultiplexing / combining unit 124 are lower than the combining threshold, the signal level of the combined signal generated by the demultiplexing / combining unit 124 is lower than the signal threshold. The combining threshold is stored, for example, in a non-volatile memory of the control unit 12.

[0046] 4 shows a schematic front view and a schematic plan view of the antenna 1. Specifically, (a) is a schematic front view of the antenna 1 showing the communication space S of the antenna 1. (b) is a schematic plan view of the antenna 1 showing the communication space S of the antenna 1.

[0047] The communication space S is a substantially partially spherical space centered on the antenna 1, i.e., a part of the substantially spherical space centered on the antenna 1. When the communication device 2 is located in the communication space S, the signal level of the received signal received by the antenna 1 is equal to or greater than the signal threshold. On the other hand, when the communication device 2 is located outside the communication space S, the signal level of the received signal received by the antenna 1 is smaller than the signal threshold. Therefore, the antenna 1 can stably communicate with the communication device 2 located in the communication space S. The communication space S includes multiple (17) individual communication spaces IS.

[0048] The individual communication space IS is a space corresponding to the element E. The range of the individual communication space IS is determined based on the threshold angle of the corresponding element E. The "threshold angle" is the angle between the direction in which the signal level of the received signal is maximum (hereinafter referred to as the "reference direction") and the direction in which the signal level of the received signal is approximately the same as the signal threshold (hereinafter referred to as the "threshold direction"). The reference direction is a direction perpendicular to the surface of the element E. When the communication device 2 moves from the reference direction to the threshold direction while the distance between the antenna 1 and the communication device 2 remains constant, the signal level of the received signal decreases. The threshold angle of the element E is 40°. That is, for example, the range of the individual communication space IS corresponding to the element E1 is the range within an azimuth angle of 80° and an elevation angle of 80°. The range of the communication space S is the range within an azimuth angle of 360° and an elevation angle of 130°.

[0049] In the following description, when the individual communication spaces IS corresponding to the elements E1 to E17 are to be distinguished from one another, "(1)" to "(17)" are added to "individual communication space IS." That is, for example, the individual communication space IS corresponding to the element E1 is called "individual communication space IS(1)," the individual communication space IS corresponding to the element E2 is called "individual communication space IS(2)," and the individual communication space IS corresponding to the element E17 is called "individual communication space IS(17)."

[0050] In FIG. 4, the individual communication spaces IS(1) to IS(9), IS(13), and IS(17) are indicated by dashed lines, and the individual communication spaces IS(10) to IS(12), IS(14) to IS(16) are not shown.

[0051] When a communication device 2 is located in one individual communication space IS, the element E corresponding to the individual communication space IS can receive a received signal having a signal level equal to or greater than the signal threshold. That is, for example, when the communication device 2 is located in an individual communication space IS(1), the corresponding element E1 can receive a received signal (1) having a signal level equal to or greater than the signal threshold. On the other hand, when the communication device 2 is located outside the individual communication space IS(1), the corresponding element E1 receives a received signal (1) having a signal level smaller than the signal threshold.

[0052] An individual communication space IS overlaps with other individual communication spaces IS. For example, the individual communication space IS(1) overlaps with the individual communication space IS(2), the individual communication space IS(8), and the individual communication space IS(17).

[0053] One individual communication space IS, one surface (top surface 111, side surface 113, inclined surface 114) of the housing 11, one element E, one communication path R, and one switch SW correspond to one another. That is, for example, the individual communication space IS(1), one side surface 113, element E1, communication path R1, and switch SW1 correspond to one another. When the communication device 2 is located in the individual communication space IS(1), the communication unit 121 can communicate with the communication device 2 via the communication line L, element E1, communication path R1, and switch SW1.

[0054] ● Operation of this antenna The operation of the present antenna 1 will be described below. In the following description, the operation of the present antenna 1 is completed based on the operation of the user who uses the present antenna 1.

[0055] The operation of the antenna 1 includes a normal operation and a combining operation. The "normal operation" is an operation in which a receiving signal is received by the receiving unit 121R and a transmitting signal is transmitted by the transmitting unit 121T. The "combining operation" is an operation in which a combined signal is generated by the multiplexing / demultiplexing unit 124.

[0056] During operation of the antenna 1, the elements E constantly attempt to receive received signals. The switches SW constantly enable the transmission of received signals received by the corresponding elements E to the communication unit 121 via the corresponding communication path R, in order. That is, for example, switch SW1 enables transmission of received signal (1) to the communication unit 121, then switch SW2 enables transmission of received signal (2) to the communication unit 121, then switch SW3 enables transmission of received signal (3) to the communication unit 121, and finally switch SW17 enables transmission of received signal (17) to the communication unit 121, after which switch SW1 again enables transmission of received signal (1) to the communication unit 121. The level detection unit 122 constantly detects the signal levels of received signals received by the elements E (received signals transmitted via communication path R) in order. That is, for example, the level detection unit 122 detects signal level (1), then detects signal level (2), then detects signal level (3), and finally detects signal level (17), and then detects signal level (1) again.

[0057] ●Normal operation 5 is a flowchart showing an embodiment of a communication method according to the present invention, illustrating the operation (normal operation) of the present antenna 1. That is, the normal operation is an example of the present method.

[0058] An outline of normal operation of the present antenna 1 will be explained below with reference to Fig. 5. In the following explanation, Fig. 3 will be referred to as appropriate.

[0059] First, the level detection unit 122 detects the signal levels (1) to (17). Next, the path selection unit 123 selects, as the main path, the communication path R (first path) through which the received signal having the largest signal level that is equal to or greater than the signal threshold is transmitted (ST1: main path selection step). This communication path R functions as the main path.

[0060] At this time, the receiving unit 121R receives the reception signal from the communication device 2 via the main path (ST2).

[0061] Furthermore, the transmitting unit 121T transmits the transmission signal to the communication device 2 via the main path (ST3).

[0062] Next, the path selection unit 123 determines whether or not there is a communication path R (second path) through which a received signal having a signal level equal to or greater than the signal threshold and the second highest signal level is transmitted. That is, the path selection unit 123 determines whether or not there is a communication path R that can function as a sub-path (ST4: sub-path determination step).

[0063] If the communication route R exists (ST4: Yes), the route selection unit 123 selects the communication route R as a sub-route (ST5: sub-route selection step). The communication route R functions as a sub-route.

[0064] At this time, the receiving unit 121R receives the reception signal from the communication device 2 via both the main route and the sub-route (ST6: receiving step). The process (ST6) is an example of the receiving step in the present invention.

[0065] Furthermore, the transmitting unit 121T transmits the transmission signal to the communication device 2 via the main path (ST7: transmitting step). The process (ST7) is an example of the transmitting step in the present invention.

[0066] On the other hand, when there is no communication route R that can function as a sub-route (ST4: No), the operation of the antenna 1 returns to the process (ST4).

[0067] Next, the path selection unit 123 determines whether the "signal level of the received signal transmitted via the sub-path" is smaller than the signal threshold value (ST8).

[0068] If the "signal level of the received signal transmitted via the secondary route" is smaller than the signal threshold value (ST8: Yes), the route selection unit 123 cancels the selection of the secondary route (ST9).

[0069] Then, the operation of the antenna 1 returns to the process (ST2).

[0070] On the other hand, when the "signal level of the received signal transmitted via the sub-path" is equal to or greater than the signal threshold (ST8: No), the path selection unit 123 determines whether the "signal level of the received signal transmitted via the sub-path" is greater than the "signal level of the received signal transmitted via the main path" (ST10: main path determination step).

[0071] When the "signal level of the received signal transmitted via the sub-route" is greater than the "signal level of the received signal transmitted via the main route" (ST10: Yes), the route selection unit 123 selects the "communication route R that was functioning as the sub-route" as the new main route, and selects the "communication route R that was functioning as the main route" as the new sub-route (ST11: re-selection step).

[0072] Then, the operation of the antenna 1 returns to the process (ST6).

[0073] On the other hand, when the "signal level of the received signal transmitted via the secondary path" is equal to or lower than the "signal level of the received signal transmitted via the main path" (ST10: No), the control unit 12 determines whether the operation of the antenna 1 is terminated based on the user's operation (ST12).

[0074] Next, when the operation of the antenna 1 is ended based on the operation of the user (ST12: Yes), the operation of the antenna 1 ends.

[0075] On the other hand, if the operation of the antenna 1 is not terminated (ST12: No), the operation of the antenna 1 returns to the process (ST8).

[0076] Fig. 6(a) is a schematic front view of the antenna 1, showing an example of operation (normal operation) of the antenna 1. Fig. 6(b) is a schematic plan view of the antenna 1, showing an example of operation (normal operation) of the antenna 1. Fig. 6 shows a state in which the communication device 2 is located in the individual communication space IS(1).

[0077] Figures 6, 8, 10, 12, 14, and 16 show the communication device 2 moving around the moon's satellite orbit in the order of individual communication space IS(1), individual communication space IS(9), individual communication space IS(17), individual communication space IS(13), and individual communication space IS(5). In these figures, the individual communication spaces IS(1) to IS(9), IS(13), and IS(17) are indicated by dashed lines, and the individual communication spaces IS(10) to IS(12), IS(14) to IS(16) are not shown. In these figures, the current position of the communication device 2 is indicated by a solid line, and the positions of the communication device 2 before and after the movement are indicated by a two-dot chain line. In these figures, the direction in which the communication device 2 moves (the direction in which the communication device 2 rotates) is indicated by a thick arrow. In the following description, the direction indicated by the thick arrow is the "rotation direction."

[0078] 7 is a functional block diagram of the present antenna 1, showing an example of operation (normal operation) of the present antenna 1. The figure shows how the present antenna 1 communicates with the communication device 2 shown in FIG.

[0079] In Figures 7, 9, 11, 13, 15, and 17, the manner in which a received signal is transmitted via the main path and the manner in which a transmitted signal is transmitted are indicated by thick solid arrows. In Figures 9, 11, 15, and 17, the manner in which a received signal is transmitted via the sub-path is indicated by thick dashed arrows. In the following explanation of Figures 8 to 17, Figure 5 will be referred to as appropriate.

[0080] First, as shown in FIG. 6, the communication device 2 is located in an individual communication space IS(1).

[0081] At this time, the signal level (1) detected by the level detection unit 122 is equal to or greater than the signal threshold value and is the largest among the signal levels (1) to (17). The signal levels (2) to (17) are smaller than the signal threshold value.

[0082] Next, the path selection unit 123 selects, as the main path, the communication path R1 through which the received signal (1) having the highest signal level is transmitted (ST1). That is, the path selection unit 123 selects, as the main path, the communication path R1 from the communication paths R based on the detection result of the level detection unit 122. Of the communication paths R, the communication path R1 functions as the main path.

[0083] At this time, the switch SW1 enables transmission of the received signal (1) having the highest signal level to the communication unit 121 via the communication path R1 (main path) based on the detection result of the level detection unit 122. At this time, communication is established via the communication line L and the communication path R1.

[0084] 7, the receiving unit 121R is able to receive the reception signal (1) via the communication path R1 (main path) (ST2), and the transmitting unit 121T is able to transmit the transmission signal (1) to the communication device 2 via the communication path R1 (main path) (ST3).

[0085] 8 is a schematic front view of the antenna 1, showing an example of operation (normal operation) of the antenna 1. The figure shows a state in which the communication device 2 is located in the individual communication space IS(1) and the individual communication space IS(9).

[0086] 9 is a functional block diagram of the present antenna 1, showing an example of operation (normal operation) of the present antenna 1. The figure shows how the present antenna 1 communicates with the communication device 2 shown in FIG.

[0087] As shown in FIG. 8, the communication device 2 moves in the circular direction and is located in a space where the individual communication space IS(1) and the individual communication space IS(9) overlap.

[0088] At this time, as communication device 2 moves, signal level (9) increases. Meanwhile, signal level (1) decreases. As a result, signal level (1) is equal to or greater than the signal threshold and is the highest of signal levels (1) to (17). Signal level (9) is equal to or greater than the signal threshold and is the second highest of signal levels (1) to (17). Signal levels (2) to (8) and (10) to (17) are lower than the signal threshold.

[0089] Next, the route selection unit 123 selects, as the sub-route, the communication route R9 through which the received signal (9) having the second highest signal level is transmitted (ST4: Yes, ST5). That is, the route selection unit 123 selects, as the sub-route, the communication route R9 from the communication route R based on the detection result of the level detection unit 122. Here, the route selection unit 123 has already selected, as the main route, the communication route R1 through which the received signal (1) having the first highest signal level is transmitted. Therefore, of the communication routes R, the communication route R1 functions as the main route, and the communication route R9 functions as the sub-route.

[0090] At this time, the switch SW9 enables transmission of the received signal (9) having the second highest signal level to the communication unit 121 via the communication path R9 (sub-path) based on the detection result of the level detection unit 122. Here, the switch SW(1) has already enabled transmission of the received signal (1) to the communication unit 121 via the communication path R1 (main path). That is, the switch SW1 enables transmission of the received signal (1) having the first highest signal level to the communication unit 121, and the switch SW9 enables transmission of the received signal (9) having the second highest signal level to the communication unit 121. In this way, in addition to communication via the communication line L and the communication path R1, communication via the communication line L and the communication path R9 is established.

[0091] 9, the receiving unit 121R can receive the received signal (1) via the communication path R1 (main path) (ST6). The receiving unit 121R can also receive the received signal (9) via the communication path R9 (sub-path) (ST6). The transmitting unit 121T can also transmit the transmitted signal (1) to the communication device 2 via the communication path R1 (main path) (ST7). That is, even if the path selecting unit 123 selects the communication path R9 as the sub-path, the transmitted signal (1) is transmitted to the communication device 2 only via the communication path R1 (main path) through which the received signal (1) was previously transmitted (communication was established).

[0092] At this time, as described above, the signal level (9) is equal to or greater than the signal threshold (ST8: No). Also, the signal level (1) of the received signal (1) transmitted via the communication path R1 is greater than the signal level (9) of the received signal (9) transmitted via the communication path R9 (ST10: No).

[0093] 10 is a schematic front view of the antenna 1, illustrating an example of operation (normal operation) of the antenna 1. The figure shows a state in which the communication device 2 is located in the individual communication space IS(1) and the individual communication space IS(9). 11 is a functional block diagram of the present antenna 1, showing an example of operation (normal operation) of the present antenna 1. The figure shows how the present antenna 1 communicates with the communication device 2 shown in FIG.

[0094] As shown in FIG. 10, the communication device 2 further moves in the circular direction.

[0095] At this time, of the communication paths R, communication path R1 functions as the main path, and communication path R9 functions as the sub-path. Here, as communication device 2 moves, signal level (9) becomes even higher. On the other hand, signal level (1) becomes lower. As a result, signal level (9) is equal to or higher than the signal threshold and is the highest of signal levels (1) to (17) (ST8: No). Signal level (1) is equal to or higher than the signal threshold and is the second highest of signal levels (1) to (17). Signal levels (2) to (8) and (10) to (17) are lower than the signal threshold. In other words, as communication device 2 moves, signal level (9) becomes higher than signal level (1) (ST10: Yes). Also, signal level (1) becomes lower than signal level (9) (ST10: Yes).

[0096] Next, the path selection unit 123 selects the communication path R9, through which the received signal (9) having the highest signal level (a signal level greater than the signal level (1)) is transmitted, as the main path instead of the communication path R1 (ST11). The path selection unit 123 selects the communication path R1, through which the received signal (1) having the second highest signal level (a signal level smaller than the signal level (9)) is transmitted, as the sub-path instead of the communication path R9 (ST11). That is, based on the detection result of the level detection unit 122, the path selection unit 123 selects the communication path R9 as the new main path and the communication path R1 as the new sub-path. Of the communication paths R, the communication path R9 functions as the new main path, and the communication path R1 functions as the new sub-path. In other words, the path selection unit 123 switches the functions of the communication paths R1 and R9 based on the detection result of the level detection unit 122. That is, the path selection unit 123 switches between the main path and the sub-path based on the detection result of the level detection unit 122.

[0097] At this time, the switch SW1 has already enabled transmission of the received signal (1) to the communication unit 121, and the switch SW9 has already enabled transmission of the received signal (9) to the communication unit 121. In other words, communication via the communication line L and the communication path R1, and communication via the communication line L and the communication path R9 have already been established.

[0098] 11, the receiving unit 121R can receive the received signal (9) via the communication path R9 (main path) (ST6). The receiving unit 121R can also receive the received signal (1) via the communication path R1 (sub-path) (ST6). The transmitting unit 121T can also transmit the transmitted signal (9) to the communication device 2 via the communication path R9 (main path) (ST7). That is, even if the path selecting unit 123 selects the communication path R1 as the sub-path, the transmitted signal (9) is transmitted to the communication device 2 only via the communication path R9 (main path) through which the received signal (9) was previously transmitted (communication was established).

[0099] 12 is a schematic front view of the antenna 1, showing an example of operation (normal operation) of the antenna 1. The figure shows a state in which the communication device 2 is located in the individual communication space IS(9). 13 is a functional block diagram of the present antenna 1, showing an example of operation (normal operation) of the present antenna 1. The figure shows how the present antenna 1 communicates with the communication device 2 shown in FIG.

[0100] As shown in FIG. 12, the communication device 2 further moves in the circular direction and is located outside the individual communication space IS(1) and in the individual communication space IS(9).

[0101] At this time, as a result of the movement of communication device 2, signal level (9) is equal to or greater than the signal threshold and is the largest among signal levels (1) to (17). Signal levels (1) to (8) and (10) to (17) are smaller than the signal threshold (ST8: Yes).

[0102] Next, the route selection unit 123 cancels the selection of the sub-route for the communication route R1 (ST9). As a result, only the communication route R9 functions as the main route. In other words, communication via the communication line L and the communication route R9 has already been established.

[0103] 13, the receiving unit 121R can receive a reception signal (9) via the communication path R9 (main path) (ST2), and the transmitting unit 121T can transmit a transmission signal (9) to the communication device 2 via the communication path R9 (main path) (ST3).

[0104] 14 is a schematic front view of the antenna 1, illustrating an example of operation (normal operation) of the antenna 1. The figure shows a state in which the communication device 2 is located in a space where the individual communication space IS(9) and the individual communication space IS(17) overlap. 15 is a functional block diagram of the present antenna 1, showing an example of operation (normal operation) of the present antenna 1. The figure shows how the present antenna 1 communicates with the communication device 2 shown in FIG.

[0105] As shown in FIG. 14, the communication device 2 further moves in the circular direction and is positioned in a space where the individual communication space IS(9) and the individual communication space IS(17) overlap.

[0106] At this time, as a result of the movement of communication device 2, the signal level of received signal (9) is equal to or greater than the signal threshold and is the highest among the signal levels of received signals (1) to (17). The signal level of received signal (17) is equal to or greater than the signal threshold and is the second highest among the signal levels of received signals (1) to (17). The signal levels of received signals (1) to (8) (10) to (16) are lower than the signal threshold.

[0107] Next, the route selection unit 123 selects the communication route R17, which transmits the received signal (17) having the second highest signal level, as the sub-route (ST4: Yes, ST5). Here, the route selection unit 123 has already selected the communication route R1, which transmits the received signal (9) having the first highest signal level, as the main route. Therefore, of the communication routes R, the communication route R9 functions as the main route, and the communication route R17 functions as the sub-route.

[0108] At this time, the switch SW9 enables the transmission of the received signal (9) having the highest signal level to the communication unit 121, and the switch SW17 enables the transmission of the received signal (17) having the second highest signal level to the communication unit 121. At this time, in addition to the communication via the communication line L and the communication path R9, communication via the communication line L and the communication path R17 is established.

[0109] 15, the receiving unit 121R can receive a receiving signal (9) via communication path R9 (main path) (ST6). The receiving unit 121R can also receive a receiving signal (17) via communication path R17 (sub-path) (ST6). The transmitting unit 121T can also transmit a transmitting signal (9) to the communication device 2 via communication path R9 (main path) (ST7).

[0110] 16 is a schematic front view of the antenna 1, showing an example of operation (normal operation) of the antenna 1. The figure shows a state in which the communication device 2 is located in the individual communication space IS(9) and the individual communication space IS(17). 17 is a functional block diagram of the present antenna 1, showing an example of operation (normal operation) of the present antenna 1. The figure shows how the present antenna 1 communicates with the communication device 2 shown in FIG.

[0111] As shown in FIG. 16, the communication device 2 further moves in the circular direction.

[0112] Of the communication routes R, communication route R9 functions as a primary route, and communication route R17 functions as a secondary route. Here, as a result of communication device 2 moving in the circular direction, signal level (17) is equal to or greater than the signal threshold and is the highest of signal levels (1) to (17) (ST8: No). Signal level (9) is equal to or greater than the signal threshold and is the second highest of signal levels (1) to (17). Signal levels (1) to (8) and (10) to (16) are lower than the signal threshold. That is, as communication device 2 moves, signal level (17) becomes higher than signal level (9) (ST10: Yes). Also, signal level (9) becomes lower than signal level (17) (ST10: Yes).

[0113] Next, the route selection unit 123 selects, instead of the communication route R9, the communication route R17 through which the received signal (17) having the highest signal level (a signal level that is higher than the signal level (9)) is transmitted, as the main route (ST11). The route selection unit 123 selects, instead of the communication route R17, the communication route R9 through which the received signal (9) having the second highest signal level (a signal level that is lower than the signal level (17)) is transmitted, as the sub-route (ST11).

[0114] At this time, communication via the communication line L and communication route R9 and communication via the communication line L and communication route R17 have already been established.

[0115] 17, the receiving unit 121R can receive a receiving signal (17) via communication path R17 (main path) (ST6). The receiving unit 121R can also receive a receiving signal (9) via communication path R9 (sub-path) (ST6). The transmitting unit 121T can also transmit a transmitting signal (17) to the communication device 2 via communication path R17 (main path) (ST7).

[0116] Here, the control unit 12 constantly determines whether or not the normal operation of the antenna 1 is to be terminated based on the user's operation (ST12). When the user terminates the normal operation of the antenna 1 (ST12: Yes), the normal operation of the antenna 1 is terminated based on the user's operation. On the other hand, when the user does not terminate the normal operation of the antenna 1 (ST12: No), the normal operation of the antenna 1 continues (for example, ST8).

[0117] In this way, when the communication device 2 moves, for example, if the signal level of the received signal (9) transmitted via the communication path R9 (sub-path) is greater than the signal level of the received signal (1) transmitted via the communication path R1 (main path) and is the greatest among the signal levels of the received signals (1) to (17), the path selection unit 123 selects the communication path R9, which had been functioning as the sub-path, as the new main path instead of the communication path R1. Here, when the communication path R1 is functioning as the main path, the communication path R9 functions as the sub-path, and the received signal (9) is transmitted to the communication unit 121 via the communication path R9. In other words, when communication is established via the communication line L and the communication path R1, communication is also established via the communication line L and the communication path R9. Therefore, before the signal level of the received signal (1) becomes smaller than the signal threshold, the path selection unit 123 selects the communication path R9, which had been functioning as the sub-path, as the new main path. That is, before communication via communication path R1 (main path) becomes unstable (before communication is disconnected), the path selection unit 123 selects communication path R9, through which the received signal (9) was previously transmitted (communication was established), as a new main path. Therefore, the transmitter 121T can transmit the transmission signal (9) to the communication device 2 without delay via communication path R9, through which the received signal (9) was previously transmitted. Therefore, there is no time from when communication via one communication path R (main path) becomes unstable (when communication via one communication path R is disconnected) to when communication via another communication path R is established, i.e., no time during which communication between the antenna 1 and the communication device 2 is unstable. As a result, even if the relative positional relationship between the antenna 1 and the communication device 2 changes, the antenna 1 can continuously communicate with the communication device 2.

[0118] ● Composite operation The combining operation of this antenna 1 is explained below.

[0119] 18 is a schematic front view of the antenna 1, showing another example of operation (combining operation) of the antenna 1. The figure shows a state where the antenna 1 is located near the individual communication space IS(1)(9) and outside the communication space S.

[0120] In the following description, the distance between the communication device 2 and the individual communication space IS(1) is shorter than the distance between the communication device 2 and the individual communication space IS(9).

[0121] Fig. 19 is a functional block diagram of the present antenna 1, showing another example of operation (combining operation) of the present antenna 1. The figure shows how the present antenna 1 communicates with the communication device 2 shown in Fig. 18. In the figure, the transmission of a received signal via the main path is indicated by a thick solid arrow. In the figure, the transmission of a received signal via the sub-path is indicated by a thick dashed arrow. In the figure, the transmission of a combined signal is indicated by a thick double arrow.

[0122] When the combining operation is performed, signal level (1) is greater than or equal to the combining threshold and less than the signal threshold, and is the largest of signal levels (1) to (17). Signal level (9) is greater than or equal to the combining threshold and less than the signal threshold, and is the second largest of signal levels (1) to (17). Signal levels (2) to (8) and (10) to (17) are each less than the combining threshold and the signal threshold. That is, signal levels (1) to (17) are less than the signal threshold.

[0123] At this time, switch SW1 enables transmission of received signal (1) to communication unit 121, and switch SW9 enables transmission of received signal (9) to communication unit 121. However, even if receiver 121R receives received signals (1) and (9) via communication paths R1 and R9, and transmitter 121T transmits transmitted signal (1) to communication device 2 via communication path R1, communication between this antenna 1 and communication device 2 is not stable. In other words, communication via communication line L and communication path R1 and communication via communication line L and communication path R9 can be established, but these communications are not stable.

[0124] Therefore, the demultiplexing / combining unit 124 generates a composite signal by combining the received signal (1) and the received signal (9) transmitted to the demultiplexing / combining unit 124. That is, when the signal levels (1) to (17) are smaller than the signal threshold and the signal levels (1) and (9) are equal to or greater than the combining threshold, the demultiplexing / combining unit 124 combines the received signal (1) having the highest signal level with the received signal (9) having the second highest signal level to generate a composite signal. The receiving unit 121R can also receive the composite signal generated by the demultiplexing / combining unit 124.

[0125] In this way, when the signal levels (1) to (17) are smaller than the signal threshold, the demultiplexing / combining unit 124 The above Therefore, even when the communication device 2 is located outside the communication space S, the antenna 1 can communicate with the communication device 2 continuously.

[0126] Summary As described above, the antenna 1 includes an element E, a communication path R, a receiver 121R, and a transmitter 121T. The receiver 121R receives a reception signal from the communication device 2 via a first path (e.g., communication path R1) and a second path (e.g., communication path R9). The transmitter 121T transmits a transmission signal to the communication device 2 only via the first path. With this configuration, when communication via the first path is established, communication via the second path is also established. Therefore, before communication via the first path becomes unstable (before communication via the first path is disconnected), the transmitter 121T can transmit a transmission signal to the communication device 2 without delay via the second path through which the reception signal was previously transmitted. Therefore, there is no time during which communication via the first route becomes unstable (when communication via the first route is disconnected) until communication via another communication route R is established, i.e., no time during which communication between the antenna 1 and communication device 2 is unstable. As a result, even if the relative positional relationship between the antenna 1 and communication device 2 changes, the antenna 1 can continuously communicate with communication device 2.

[0127] As explained above, the antenna 1 includes the level detection unit 122. With this configuration, the level detection unit 122 detects the signal levels of the received signals (1) to (17) transmitted via the communication paths R1 to R17. As a result, the antenna 1 can operate (for example, select the main path, select the sub-path, operate the switch SW, operate the multiplexer / demultiplexer 124, etc.) based on the detection result of the level detection unit 122.

[0128] As described above, the antenna 1 includes a path selection unit 123. Of the communication paths R1 to R17, one communication path R functions as a main path through which a received signal and a transmitted signal are transmitted. Of the communication paths R1 to R17, one communication path R excluding the main path functions as a sub-path through which a received signal is transmitted. The path selection unit 123 selects a first path (e.g., communication path R9) as the main path based on the detection result of the level detection unit 122. With this configuration, when communication via the second path (main path) is established, communication via the first path (sub-path) is also established. Therefore, before communication via the second path becomes unstable (before communication via the second path is disconnected), the path selection unit 123 selects the first path through which a received signal was previously transmitted (communication was established) as a new main path. Therefore, the transmitter 121T can transmit the transmission signal to the communication device 2 without delay via the first route through which the received signal was previously transmitted. Therefore, there is no time from when communication via the second route becomes unstable (when communication via the second route is disconnected) to when communication via another communication route R is established, that is, no time when communication between the antenna 1 and the communication device 2 is unstable. As a result, even if the relative positional relationship between the antenna 1 and the communication device 2 changes, the antenna 1 can continuously communicate with the communication device 2.

[0129] As described above, the antenna 1 includes a path selection unit 123. Of the communication paths R1 to R17, one communication path R functions as a main path through which a received signal and a transmitted signal are transmitted. Of the communication paths R1 to R17, one communication path R other than the main path functions as a sub-path through which a received signal is transmitted. The path selection unit 123 selects a second path (e.g., communication path R1) as a sub-path based on the detection result of the level detection unit 122. According to this configuration, when communication via the first path (main path) is established, communication via the second path (sub-path) is also established. Here, the path selection unit 123 always selects an appropriate sub-path based on the detection result of the level detection unit 122. Therefore, before communication via the first path becomes unstable (before communication via the first path is disconnected), the path selection unit 123 can select the second path through which a received signal was previously transmitted (communication was established) as a new main path. Therefore, the transmitter 121T can transmit the transmission signal to the communication device 2 without delay via the second route through which the received signal was previously transmitted. Therefore, there is no time from when communication via the first route becomes unstable (when communication via the first route is disconnected) to when communication via another communication route R is established, that is, no time when communication between the antenna 1 and the communication device 2 is unstable. As a result, even if the relative positional relationship between the antenna 1 and the communication device 2 changes, the antenna 1 can continuously communicate with the communication device 2.

[0130] According to the above description, when the signal level of a received signal transmitted via the second path (e.g., communication path R9) becomes higher than the signal level of a received signal transmitted via the first path (e.g., communication path R1), the path selection unit 123 selects the second path as the main path instead of the first path. With this configuration, the communication unit 121 can communicate with the communication device 2 via the second path. At this time, the receiving unit 121R receives the received signal via the second path through which the received signal having a high signal level is transmitted. The transmitting unit 121T transmits the transmission signal to the communication device 2 via the second path through which the received signal having a high signal level is transmitted. Therefore, problems caused by a low signal level (e.g., noise generation, malfunction of the antenna 1 or the communication device 2, communication failure, etc.) are prevented. As a result, even if the relative positional relationship between the antenna 1 and the communication device 2 changes, the antenna 1 can communicate with the communication device 2 continuously and stably.

[0131] According to the above explanation, when the signal level of a received signal transmitted via a first path (e.g., communication path R1) becomes lower than the signal level of a received signal transmitted via a second path (e.g., communication path R9), the path selection unit 123 selects the first path as the sub-path instead of the second path. With this configuration, the second path does not function as the sub-path. The receiving unit 121R receives received signals via both the first path and the second path, and the transmitting unit 121T transmits transmitted signals via the second path. Therefore, the second path can function as the main path along which the received signal and transmitted signals are transmitted.

[0132] According to the above explanation, the signal level of the received signal transmitted via the main path (e.g., communication path R1) is the highest among the signal levels of the multiple received signals. That is, based on the detection result of the level detection unit 122, the path selection unit 123 selects, as the main path, the communication path R through which the received signal having the highest signal level is transmitted. This configuration prevents problems caused by low signal levels (e.g., noise generation, malfunction of the antenna 1 or communication device 2, communication failure, etc.). As a result, even if the relative positional relationship between the antenna 1 and communication device 2 changes, the antenna 1 can communicate with the communication device 2 continuously and stably.

[0133] According to the above description, the signal level of the received signal transmitted via the sub-path (e.g., communication path R9) is the second highest among the signal levels of the multiple received signals. That is, based on the detection result of the level detection unit 122, the path selection unit 123 selects, as the sub-path, the communication path R through which the received signal having the second highest signal level is transmitted. With this configuration, when communication via the main line is established, communication via the sub-path through which the received signal having the second highest signal level is transmitted is also established. As a result, even if the path selection unit 123 selects the second path, which was previously the sub-path, as the new main path, problems caused by a low signal level (e.g., noise generation, malfunction of the antenna 1 or communication device 2, communication failure, etc.) are prevented. Furthermore, the path selection unit 123 can select, as the main path, the communication path R through which the received signal having the highest signal level is transmitted.

[0134] According to the above description, the antenna 1 includes the multiplexer / demultiplexer 124. When the signal level of each of the multiple received signals is lower than the signal threshold, the multiplexer / demultiplexer 124 generates a composite signal by combining at least the received signals transmitted via the first path (e.g., communication path R1) and the received signals transmitted via the second path (e.g., communication path R9) among the multiple received signals. The receiver 121R receives the composite signal. With this configuration, the signal level of the composite signal is higher than the signal levels of each of the multiple received signals before being combined. Therefore, when the communication device 2 is located outside the communication space S or when the antenna 1 is affected by an obstacle (e.g., another satellite), problems caused by a low signal level (e.g., noise generation, malfunction of the antenna 1 or the communication device 2, communication failure, etc.) are prevented. As a result, the antenna 1 can continuously communicate with the communication device 2 even when the communication device 2 is located outside the communication space S.

[0135] According to the above description, the antenna 1 can communicate with a communication device 2 located in a communication space S. The communication space S includes an individual communication space IS in which a corresponding element E can communicate with the communication device 2. The elements E are planar patch antenna elements and form a polyhedral antenna. The elements E are oriented in different directions. With this configuration, the communication space S becomes wider depending on the number and orientation of the elements E. As a result, the coverage area of ​​the antenna 1 is wider. Furthermore, unlike conventional mechanically scanned antennas, the antenna 1 does not require the housing 11 to be driven to change the direction in which the element E is oriented. As a result, the antenna 1 does not require as much power as conventional mechanically scanned antennas. Furthermore, in conventional mechanically scanned antennas, the drive unit that drives the housing malfunctions due to the influence of regolith on the lunar surface. However, the antenna 1, which does not require the drive unit, does not malfunction due to the influence of regolith.

[0136] According to the above description, the antenna 1 is installed on a lunar rover that travels on the surface of the moon, i.e., on the surface of the moon (the earth's surface of a celestial body). The communication device 2 is an artificial satellite that orbits the moon (celestial body). With this configuration, the antenna 1 can continuously communicate with the artificial satellite (communication device 2) that moves around the moon. Furthermore, unlike conventional mechanically scanned antennas, the antenna 1 does not require driving the housing 11 to change the direction in which the element E is pointed. As a result, the antenna 1 does not require as much power as conventional mechanically scanned antennas. Furthermore, the antenna 1, which does not require a driving unit to drive the housing in a mechanically scanned antenna, does not malfunction due to the influence of regolith.

[0137] ●Variations● Next, a modified example of the present antenna 1 will be described, focusing on the differences from the embodiment of the present antenna 1 described above (hereinafter referred to as the "first embodiment"). In the following description, for convenience of explanation, the same components as those in the first embodiment and components having common functions are assigned the same reference numerals as those in the first embodiment, unless otherwise specified, and their explanation will be omitted. In addition, in the following description of the modified example, reference will be made to Figures 1, 2, 4, 8, and 10 as appropriate.

[0138] FIG. 20 is a block diagram of an antenna 1A, which is a modified example of the antenna 1. This figure shows how the antenna 1 communicates with the communication device 2 shown in FIG. In the figure, the transmission of the received signal (9) and the transmission of the transmitted signal (9) are indicated by thick solid arrows. In the figure, the transmission of the received signal (1) is indicated by thick dashed arrows. In the figure, the transmission of the received signals (2) to (8), (10) to (17) and the transmission signals (1) to (8), (10) to (17) is omitted from the illustration.

[0139] The modified example differs from the first embodiment in that the antenna 1A includes a plurality (17) of attenuation units AN1, AN2, AN3, AN4, AN5, AN6, AN7, AN8, AN9, AN10, AN11, AN12, AN13, AN14, AN15, AN16, and AN17 instead of the switch SW. In the following description, when the attenuation units AN1 to AN17 are not particularly distinguished from one another, they are collectively referred to as "attenuation unit AN." The attenuation units AN are, for example, known attenuators.

[0140] The attenuation unit AN can attenuate the received signal and the transmitted signal transmitted from the element E to the attenuation unit AN via the communication path R. The attenuation unit AN does not attenuate the received signal transmitted to the attenuation unit AN via each of the main path and the sub-path. The attenuation unit AN does not attenuate the transmitted signal transmitted to the attenuation unit AN via the main path. The attenuation unit AN attenuates the received signal and the transmitted signal transmitted to the attenuation unit AN via a communication path R that does not function as a main path or a sub-path. In other words, the attenuation unit AN attenuates the received signal having a signal level smaller than the signal threshold. The attenuation unit AN is disposed on the communication path R corresponding to the corresponding element E. The received signal received by the element E is transmitted to the corresponding attenuation unit AN via the corresponding communication path R. The transmitted signal transmitted by the communication unit 121 is transmitted to the attenuation unit AN.

[0141] The receiving unit 121R can receive a received signal transmitted from the element E to the corresponding attenuation unit AN. The transmitting unit 121T can transmit a transmitted signal to the communication device 2 via the communication path R, the corresponding attenuation unit AN, and the corresponding element E.

[0142] One individual communication space IS, one surface (top surface 111, side surface 113, inclined surface 114) of the housing 11, one element E, one communication path R, and one attenuation unit AN correspond to one another. That is, for example, the individual communication space IS(1), one side surface 113, element E1, communication path R1, and attenuation unit AN1 correspond to one another. When the communication device 2 is located in the individual communication space IS(1), the communication unit 121 can communicate with the communication device 2 via the communication line L, element E1, communication path R1, and attenuation unit AN1.

[0143] In the following description, the position of communication device 2 is the same as the position of communication device 2 shown in FIG. 8. Therefore, signal level (1) is greater than signal level (9). Of communication paths R, communication path R1 functions as a main path, and communication path R9 functions as a sub-path. Signal levels (2) to (8) and (10) to (17) are smaller than the signal threshold. Communication path R1 is an example of a first path in the present invention. Communication path R9 is an example of a second path in the present invention.

[0144] Next, as shown in FIG. 10, the communication device 2 moves further in the circular direction.

[0145] 20, the attenuation units AN1 and AN9 arranged on the communication paths R1 and R9 do not attenuate the received signals (1) and (9) based on the detection result of the level detection unit 122. That is, the attenuation units AN1 and AN9 do not attenuate the received signal (9) having the highest signal level and the received signal (1) having the second highest signal level based on the detection result of the level detection unit 122. On the other hand, the attenuation units AN2 to AN8 and AN10 to AN17 attenuate the received signals (2) to (8), (10) to (17) (for example, until the signal levels become almost 0) based on the detection result of the level detection unit 122. That is, based on the detection result of the level detection unit 122, the attenuation units AN2 to AN8, AN10 to AN17 attenuate the received signals (2) to (8), (10) to (17) having a signal level lower than the signal threshold and transmitted to the attenuation units AN2 to AN8, AN10 to AN17 via communication paths R2 to R8, R9 to R17 different from the communication paths R1 and R9.

[0146] 20, the attenuation unit AN9 disposed on the communication path R9 does not attenuate the transmission signal (9) based on the detection result of the level detection unit 122. That is, when the signal level (9) is equal to or greater than the signal threshold and is the largest, the attenuation units AN1 to AN8 and AN10 to AN17 attenuate the transmission signals (1) to (8), (10) to (17), and the attenuation unit AN9 does not attenuate the transmission signal (9). That is, when the signal level (9) is greater than the signal level (1), the attenuation unit AN1 attenuates the transmission signal (1), and the attenuation unit AN9 does not attenuate the transmission signal (9). On the other hand, the attenuation units AN1 to AN8 and AN10 to AN17 attenuate the transmission signals (1) to (8), (10) to (17) based on the detection result of the level detection unit 122. That is, when the signal level (9) becomes greater than the signal level (1), the attenuation units AN1 to AN8 and AN10 to AN17 attenuate the transmission signals (1) to (8) and (10) to (17). The communication paths R2 to R8 and R10 to R17 are an example of the third path in the present invention.

[0147] In this way, the received signals (1) and (9) transmitted to the attenuation units AN1 and AN9 are transmitted to the receiving unit 121R, and the received signals (2) to (8), (10) to (17) transmitted to the attenuation units AN2 to AN8 and AN10 to AN17 are not transmitted to the receiving unit 121R. Also, the transmitted signal (1) transmitted to the attenuation unit AN1 is transmitted to the communication device 2, and the transmitted signals (2) to (17) transmitted to the attenuation units AN2 to AN17 are not transmitted to the communication device 2. As a result, the receiving unit 121R can receive only the received signals (1) and (9) out of the received signals (1) to (17). Also, the transmitting unit 121T can transmit only the transmitted signal (1) out of the transmitted signals (1) to (17) to the communication device 2.

[0148] As explained above, the antenna 1A includes the attenuation unit AN. The attenuation unit AN attenuates at least one of the received signal and the transmitted signal transmitted to the attenuation unit AN based on the detection result of the level detection unit 122. With this configuration, the antenna 1 can transmit a desired received signal from the element E to the receiving unit 121R based on the detection result of the level detection unit 122. Furthermore, the antenna 1 can transmit a desired transmitted signal from the transmitting unit 121T to the element E based on the detection result of the level detection unit 122. As a result, the receiving unit 121R can receive the desired received signal. The transmitting unit 121T can transmit the desired transmitted signal.

[0149] According to the above description, when the signal level of the received signal transmitted via the second path (e.g., communication path R9) becomes higher than the signal level of the received signal transmitted via the first path (e.g., communication path R1), the attenuation unit AN attenuates the transmission signal transmitted to the attenuation unit AN via the first path, but does not attenuate the transmission signal transmitted to the attenuation unit AN via the second path. With this configuration, the transmitter 121T transmits the transmission signal to the communication device 2 only via the second path through which the received signal having a high signal level is transmitted. Therefore, problems caused by a low signal level (e.g., noise generation, malfunction of the antenna 1 or the communication device 2, communication failure, etc.) are prevented. As a result, the antenna 1 can communicate with the communication device 2 continuously and stably even if the relative positional relationship between the antenna 1 and the communication device 2 changes.

[0150] According to the above explanation, the communication path R includes a third path (communication paths R2 to R8, R10 to R17) that is different from each of the first path and the second path. The attenuation unit AN attenuates each of the received signal and the transmitted signal transmitted to the attenuation unit AN via the third path. According to this configuration, the received signal is not received by the receiving unit 121R via the third path. Furthermore, the transmitted signal is not received by the communication device 2 via the third path. As a result, the receiving unit 121R can receive the desired received signal. The transmitting unit 121T can transmit the desired transmitted signal.

[0151] ●Other embodiments●

[0152] The installation location of this antenna is not particularly limited. For example, this antenna may be installed on a celestial body other than the moon or on an artificial satellite (for example, an earth-orbiting satellite or a lunar-orbiting satellite).

[0153] The antenna may also communicate with two or more communication devices, or may communicate with other antenna systems (e.g., electronically scanned antenna systems, mechanically scanned antenna systems, etc.) That is, for example, the antenna may have two communication units, one of which communicates with a first communication device and the other of which communicates with a second communication device.

[0154] Furthermore, this antenna (polyhedral antenna) may be divided and arranged. That is, for example, of the multiple (17) elements in the present invention, 11 elements constituting a part of the polyhedral antenna and 6 elements constituting a part of the remaining polyhedral antenna may be arranged in physically separated positions. According to this configuration, this antenna is divided (for example, divided into two) and arranged at the installation location of this antenna (for example, a lunar rover). Therefore, this antenna does not require a large installation space. Furthermore, this antenna can be installed taking into consideration the positional relationship with other components (for example, solar cell paddles installed on a lunar rover) that will be installed at the installation location together with this antenna.

[0155] Furthermore, the communication device of the present invention is not limited to an artificial satellite orbiting a celestial body as long as it can communicate with the antenna via a wireless communication line. For example, the communication device of the present invention may be a radio station installed on the surface of the Earth, or an artificial satellite orbiting a celestial body other than the Moon.

[0156] Furthermore, the housing of the present invention is not particularly limited in shape as long as it allows the antenna to communicate continuously with the communication device. That is, for example, the housing of the present invention may be a tetradecahedron (a regular hexagonal shape when viewed from above) or a hexahedron (a regular heptagonal shape when viewed from above). The direction in which each face of the housing of the present invention faces is also not particularly limited.

[0157] Furthermore, the element in the present invention need only be capable of receiving a reception signal and transmitting a transmission signal, and does not have to be disposed on the surface of the housing. That is, for example, the present antenna does not need to have a housing.

[0158] Furthermore, the number of elements and communication paths in the present invention is not particularly limited as long as it is two or more. That is, for example, the number of elements in the present invention may be two or three or more. Also, the number of communication paths in the present invention may be two or three or more.

[0159] Furthermore, the number of sub-paths in the present invention is not limited to "1." That is, for example, the sub-path selection unit in the present invention may select "a communication path through which a received signal having the second highest signal level is transmitted" and "a communication path through which a received signal having the third highest signal level is transmitted" as sub-paths. In this case, of the multiple communication paths, the two communication paths excluding the main path function as sub-paths through which the received signal is transmitted.

[0160] Furthermore, the main path selection unit and the sub path selection unit in the present invention only need to select the main path and the sub path, respectively, based on the detection results of the level detection unit, and the operations of the main path selection unit and the sub path selection unit are not particularly limited.

[0161] Furthermore, the antenna may also include a diplexer that separates the transmission signal from the reception signal, an amplifier that amplifies the transmission signal and the reception signal, and a phase unit that controls the phase of the transmission signal and the reception signal.

[0162] Furthermore, the communication unit, level detection unit, and path selection unit of the present invention do not have to be realized by software defined radios, and the attenuation unit and synthesis unit of the present invention may be realized by software defined radios.

[0163] Furthermore, the number of switches and attenuation units in the present invention is not particularly limited. That is, for example, the number of switches and attenuation units may be "1" or may be the same as the number of elements. Also, one switch and one attenuation unit may correspond to multiple elements. Furthermore, the present antenna may or may not include both switches and attenuation units.

[0164] Furthermore, the attenuation unit of the present invention is not particularly limited as long as it attenuates at least one of the received signal and the transmitted signal transmitted to the attenuation unit based on the detection result of the level detection unit. That is, for example, the attenuation unit of the present invention may change the amount of attenuation based on the detection result of the level detection unit. Specifically, the amount of attenuation of the received signal transmitted via each of the main path and the sub-path may be greater than the amount of attenuation of the received signal transmitted via communication paths other than the main path and the sub-path.

[0165] Furthermore, the combining unit of the present invention is not particularly limited as long as it combines at least the received signal transmitted via the first path and the received signal transmitted via the second path among the multiple received signals. That is, for example, the number of received signals to be combined may be "3" or more. The combining unit may also determine the number of received signals to be combined based on the detection result of the level detection unit. The signal level of the received signals to be combined may be equal to or greater than a signal threshold.

[0166] Furthermore, the antenna does not need to include a combining section (multiplexing / demultiplexing section).

[0167] Furthermore, the predetermined threshold (signal threshold) in the present invention is not particularly limited. That is, for example, the predetermined threshold (signal threshold) in the present invention may be greater than the minimum signal level at which stable communication is possible between the antenna and the communication device. In this case, communication between the antenna and the communication device becomes even more stable. Furthermore, the signal threshold in the present invention may be smaller than the minimum signal level at which stable communication is possible between the antenna and the communication device, and may be equal to or greater than the minimum signal level at which stable communication is possible between the antenna and the communication device.

[0168] ●Features of this antenna and method● The features of the antenna and method described so far are summarized below.

[0169] ●Features of this antenna This antenna (for example, this antenna 1) 1. An electronically scanned antenna system capable of communicating with a communication device (e.g., communication device 2), comprising: A plurality of elements (for example, elements E1 to E17) capable of receiving a reception signal transmitted from the communication device; A plurality of communication paths (e.g., communication paths R1 to R17) connected to each of the plurality of elements; a communication unit (for example, a communication unit 121) capable of communicating with the communication device via each of the plurality of elements and each of the plurality of communication paths; and The plurality of communication paths include: a first path (e.g., communication path R1); a second route (e.g., communication route R9) different from the first route; Including, The communication unit a receiving unit (for example, receiving unit 121R) that receives the reception signal from the communication device via each of the first path and the second path; a transmitter (for example, transmitter 121T) that transmits a transmission signal received by the communication device to the communication device via only one of the first path and the second path; Equipped with It is characterized by:

[0170] This antenna is a level detection unit (e.g., level detection unit 122) that detects the signal level of the received signal transmitted via each of the plurality of communication paths; consisting of It can also be something like this.

[0171] In this antenna, Any one of the plurality of communication paths functions as a main path through which the reception signal and the transmission signal are transmitted, Among the plurality of communication paths, one path other than the main path functions as a sub-path through which the received signal is transmitted, the electronically scanned antenna system comprises: a main path selection unit (e.g., a path selection unit 123) that selects the first path as the main path from the plurality of communication paths based on the detection result of the level detection unit; consisting of It can also be something like this.

[0172] This antenna is Any one of the plurality of communication paths functions as a main path through which the reception signal and the transmission signal are transmitted, Among the plurality of communication paths, one path other than the main path functions as a sub-path through which the received signal is transmitted, the electronically scanned antenna system comprises: a sub-path selection unit (e.g., a path selection unit 123) that selects the second path as the sub-path from the plurality of communication paths based on the detection result of the level detection unit; consisting of It can also be something like this.

[0173] In this antenna, when the signal level of the received signal transmitted via the second path becomes greater than the signal level of the received signal transmitted via the first path, the main path selection unit selects the second path as the main path instead of the first path. It can also be something like this.

[0174] In this antenna, when the signal level of the received signal transmitted via the first path becomes smaller than the signal level of the received signal transmitted via the second path, the sub-path selection unit selects the first path as the sub-path instead of the second path. It can also be something like this.

[0175] In this antenna, the signal level of the received signal transmitted via the main path is the largest among the signal levels of the plurality of received signals; It can also be something like this.

[0176] In this antenna, the signal level of the received signal transmitted via the sub-path is the second largest among the signal levels of the plurality of received signals; It can also be something like this.

[0177] This antenna is a combiner (e.g., demultiplexer / combiner 124) that combines the plurality of received signals to generate a combined signal; and When the signal level of each of the plurality of received signals is smaller than a predetermined threshold, the combining unit combines at least the received signal transmitted via the first path and the received signal transmitted via the second path among the plurality of received signals to generate the combined signal, The receiving unit receives the composite signal. It can also be something like this.

[0178] This antenna (for example, this antenna 1A) attenuation units (for example, attenuation units AN1 to AN17) that are arranged in each of the plurality of communication paths and are capable of attenuating at least one of the reception signal and the transmission signal; and the attenuation unit attenuates at least one of the reception signal and the transmission signal transmitted to the attenuation unit based on the detection result of the level detection unit. It can also be something like this.

[0179] In this antenna, when the signal level of the received signal transmitted via the second path becomes greater than the signal level of the received signal transmitted via the first path, the attenuation unit attenuates the transmitted signal transmitted to the attenuation unit via the first path and does not attenuate the transmitted signal transmitted to the attenuation unit via the second path. It can also be something like this.

[0180] In this antenna, The plurality of communication paths include: a third route (for example, communication routes R2 to R8, R10 to R17) different from each of the first route and the second route; Including, the attenuation unit attenuates each of the received signal and the transmitted signal transmitted to the attenuation unit via the third path. It can also be something like this.

[0181] In this antenna, Each of the plurality of elements is a planar patch antenna element, forming a polyhedron antenna, the electronically scanned antenna system is capable of communicating with the communication device located in a communication space (e.g., communication space S); The communication space is a plurality of individual communication spaces (e.g., individual communication spaces IS1 to IS17) corresponding to each of the elements and capable of communicating with the communication device; Including, each of the elements is oriented in a different direction; It can also be something like this.

[0182] In this antenna, the electronically scanned antenna system is mounted on a celestial body; the communication device is an artificial satellite orbiting the celestial body; It can also be something like this.

[0183] ●Features of this method The method comprises: 1. A method of communications performed by an electronically scanned antenna system capable of communicating with a communications device, comprising: the electronically scanned antenna system comprises: a plurality of elements capable of receiving a reception signal transmitted from the communication device; a plurality of communication paths connected to each of the plurality of elements; a communication unit capable of communicating with the communication device via each of the plurality of elements and each of the plurality of communication paths; With The plurality of communication paths include: The first pathway, a second path different from the first path; Including, The communication method includes: a receiving step (e.g., process (ST6)) in which the electronically scanned antenna system receives the received signal from the communication device via each of the first path and the second path; a transmitting step (e.g., process (ST7)) in which the electronically scanned antenna system transmits a transmission signal to the communication device via only one of the first path and the second path, the transmission signal being received by the communication device; Including, It is characterized by: [Explanation of symbols]

[0184] 1 antenna (electronically scanned antenna system) 1A Main antenna (electronically scanned antenna system) 11. Housing 111 Top surface 112 Bottom surface 113 Side 114 Slope E1 element E2 element E3 element E4 element E5 element E6 element E7 element E8 element E9 element E10 element E11 element E12 element E13 element E14 element E15 element E16 element E17 element R1 communication path R2 communication path R3 communication path R4 communication path R5 communication path R6 communication path R7 Communication Path R8 communication path R9 communication path R10 communication path R11 communication path R12 communication path R13 Communication Path R14 Communication Path R15 Communication Path R16 Communication Path R17 Communication Path SW switch 12 Control Unit 121 Communications Department 121R receiver 121T Transmitter 122 Level detection unit 123 Route Selection Unit 124-minute multiplexing section 2. Communication equipment L communication line S Communication Space IS individual communication space AN1 attenuation section AN2 attenuation section AN3 attenuation section AN4 attenuation section AN5 attenuation section AN6 attenuation section AN7 attenuation section AN8 attenuation section AN9 Attenuation section AN10 Attenuation section AN11 damping section AN12 damping section AN13 damping section AN14 damping section AN15 damping section AN16 damping section AN17 Damping section

Claims

1. 1. An electronically scanned antenna system capable of communicating with a communication device, comprising: a plurality of elements capable of receiving a reception signal transmitted from the communication device; a plurality of communication paths connected to each of the plurality of elements; a communication unit capable of communicating with the communication device via each of the plurality of elements and each of the plurality of communication paths; a level detection unit that detects the signal level of the received signal transmitted via each of the plurality of communication paths; an attenuation unit disposed on each of the plurality of communication paths and capable of attenuating at least one of the received signal and a transmission signal received by the communication device based on a detection result of the level detection unit; and The plurality of communication paths include: The first pathway; a second path different from the first path; Including, The communication unit a receiving unit that receives the reception signal from the communication device via each of the first path and the second path; a transmitter that transmits the transmission signal to the communication device via only one of the first path and the second path; With the reception signal attenuated by the attenuation unit is not transmitted from the attenuation unit to the reception unit via the communication path, the transmission signal attenuated by the attenuation unit is not transmitted from the attenuation unit to the element via the communication path, The received signal that is not attenuated by the attenuation unit is transmitted from the attenuation unit to the receiving unit via the communication path, The transmission signal that is not attenuated by the attenuation unit is transmitted from the attenuation unit to the element via the communication path, when the signal level of the reception signal transmitted via the second path becomes greater than the signal level of the reception signal transmitted via the first path, the attenuation unit attenuates the transmission signal transmitted to the attenuation unit via the first path and does not attenuate the transmission signal transmitted to the attenuation unit via the second path, so that the transmission signal transmitted to the attenuation unit via the first path is not transmitted from the attenuation unit to the element via the first path, and the transmission signal transmitted to the attenuation unit via the second path is transmitted from the attenuation unit to the element via the second path.

1. An electronically scanned antenna system comprising:

2. One of the plurality of communication paths functions as a main path through which the reception signal and the transmission signal are transmitted, Among the plurality of communication paths, one path other than the main path functions as a sub-path through which the received signal is transmitted, the electronically scanned antenna system comprises: a main path selection unit that selects the first path as the main path from the plurality of communication paths based on a detection result of the level detection unit; consisting of 2. The electronically scanned antenna system of claim 1.

3. One of the plurality of communication paths functions as a main path through which the reception signal and the transmission signal are transmitted, Among the plurality of communication paths, one path other than the main path functions as a sub-path through which the received signal is transmitted, the electronically scanned antenna system comprises: a sub-path selection unit that selects the second path as the sub-path from the plurality of communication paths based on a detection result of the level detection unit; consisting of 2. The electronically scanned antenna system of claim 1.

4. when the signal level of the received signal transmitted via the second path becomes greater than the signal level of the received signal transmitted via the first path, the main path selection unit selects the second path as the main path instead of the first path.

3. The electronically scanned antenna system of claim 2.

5. when the signal level of the received signal transmitted via the first path becomes smaller than the signal level of the received signal transmitted via the second path, the sub-path selection unit selects the first path as the sub-path instead of the second path.

4. The electronically scanned antenna system of claim 3.

6. the signal level of the received signal transmitted via the main path is the largest among the signal levels of the plurality of received signals; 3. The electronically scanned antenna system of claim 2.

7. the signal level of the received signal transmitted via the sub-path is the second largest among the signal levels of the plurality of received signals; 4. The electronically scanned antenna system of claim 3.

8. a combining unit that combines a plurality of the received signals to generate a combined signal; and When the signal level of each of the plurality of received signals is smaller than a predetermined threshold, the combining unit combines at least the received signal transmitted via the first path and the received signal transmitted via the second path among the plurality of received signals to generate the combined signal, The receiving unit receives the composite signal.

7. The electronically scanned antenna system of claim 6.

9. When the signal level of each of the plurality of received signals is equal to or greater than the threshold, the combining unit does not combine the plurality of received signals, the signal level of the composite signal is equal to or greater than the threshold; the threshold value is a minimum signal level at which stable communication is possible between the electronically scanned antenna system and the communication device; 9. The electronically scanned antenna system of claim 8.

10. The plurality of communication paths include: a third path different from each of the first path and the second path; Including, the attenuation unit attenuates each of the received signal and the transmitted signal transmitted to the attenuation unit via the third path.

2. The electronically scanned antenna system of claim 1.

11. Each of the plurality of elements is a planar patch antenna element, forming a polyhedron antenna, the electronically scanned antenna system is capable of communicating with the communication device located in a communication space; The communication space is a plurality of individual communication spaces corresponding to the respective elements, in which the corresponding elements can communicate with the communication device; Including, each of the elements is oriented in a different direction; 2. The electronically scanned antenna system of claim 1.

12. the electronically scanned antenna system is mounted on a celestial body; the communication device is an artificial satellite orbiting the celestial body; 2. The electronically scanned antenna system of claim 1.

13. 1. A method of communications performed by an electronically scanned antenna system capable of communicating with a communications device, comprising: the electronically scanned antenna system comprises: a plurality of elements capable of receiving a reception signal transmitted from the communication device; a plurality of communication paths connected to each of the plurality of elements; a communication unit capable of communicating with the communication device via each of the plurality of elements and each of the plurality of communication paths; a level detection unit that detects the signal level of the received signal transmitted via each of the plurality of communication paths; an attenuation unit disposed on each of the plurality of communication paths and capable of attenuating at least one of the received signal and a transmission signal received by the communication device based on a detection result of the level detection unit; With The plurality of communication paths include: The first pathway; a second path different from the first path; Including, The communication unit a receiving unit that receives the reception signal from the communication device via each of the first path and the second path; a transmitter that transmits the transmission signal to the communication device via only one of the first path and the second path; With The communication method includes: a receiving step in which the electronically scanned antenna system receives the received signal from the communication device via each of the first path and the second path; a transmitting step in which the electronically scanned antenna system transmits the transmission signal to the communication device via only one of the first path and the second path; Including, The transmitting step includes: an attenuation step in which, when the signal level of the received signal transmitted via the second path becomes greater than the signal level of the received signal transmitted via the first path, the attenuation unit attenuates the transmitted signal transmitted via the first path to the attenuation unit and does not attenuate the transmitted signal transmitted via the second path to the attenuation unit; Including, the received signal attenuated by the attenuation unit is not transmitted from the attenuation unit to the receiving unit via the communication path, the transmission signal attenuated by the attenuation unit is not transmitted from the attenuation unit to the element via the communication path, The received signal that is not attenuated by the attenuation unit is transmitted from the attenuation unit to the receiving unit via the communication path, The transmission signal that is not attenuated by the attenuation unit is transmitted from the attenuation unit to the element via the communication path, By performing the attenuation step, the transmission signal transmitted to the attenuation unit via the first path is not transmitted from the attenuation unit to the element via the first path, and the transmission signal transmitted to the attenuation unit via the second path is transmitted from the attenuation unit to the element via the second path. A communication method comprising:

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