JP2007221303A - Satellite communication antenna device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a satellite communication antenna device capable of controlling a signal property variable machine for changing the signal property of a received signal according to posture change of a satellite, and moving an angle of a null point or suppressing its occurrence to expand a transmission enabled angle region, when a desired antenna pattern is acquired for enabling communication with an earth station by combination of a plurality of antenna patterns. <P>SOLUTION: The satellite communication antenna device comprises a communication antenna 4 mounted on a satellite for permanently turning to a communication directional plane side 6, a communication antenna 5 mounted on the satellite for permanently turning to a communication inverse directional plane side 7, and a signal property variable machine connected respectively to each of the communication antennas for changing the signal property of a received signa outputted from each of the communication antennas. In addition, the satellite communication antenna device comprises a power optical multiplexer for compounding the received signal outputted from each of the signal property variable machines and inputing it into a transceiver, and a control unit for detecting received signal power outputted from the power optical multiplexer and controlling at least one of the signal property variable machines, based on change in the received power due to posture change of the satellite. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an antenna device for an artificial satellite applied to, for example, a telemetry tracking command system mounted for transmitting a telemetry signal to a ground station and a direct transmission system for transmitting mission data to the ground station. It is.

When communication is performed between the artificial satellite and the ground station, it is necessary to arrange an antenna so that communication with the ground station can be performed even if the attitude of the artificial satellite changes. For example, when the satellite is in the orbit, or when the satellite is in an attitude that rotates with respect to the ground station in the orbiting satellite, the satellite's attitude is unstable. If only the earth-oriented surface side (described later) is installed, the required power of the communication line with the ground station cannot be satisfied.
Therefore, communication may be interrupted.

  In order to solve such a problem, as an example of an antenna device intended to obtain a necessary antenna radiation pattern when communicating between an artificial satellite and a ground station, a switch and a multiplexer / demultiplexer are provided. A combined conventional technique is known (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 2001-211027 (page 3-4, FIG. 1)

  In the case of Patent Document 1, a desired antenna pattern is obtained using a combination of a plurality of antennas, a plurality of switches, and a plurality of multiplexers / demultiplexers, thereby preventing communication interruption. However, because the desired antenna pattern is obtained by combining the patterns using multiple antennas so that it can communicate with the ground station, the antenna pattern null corresponding to the change in attitude angle as the satellite rotates. There is a problem that even if it is desired to move the angle of the point to expand the communicable angle region, it cannot be expanded. A desired antenna pattern is obtained by switching the switch. Accordingly, switching the switch while the power is on causes a switch failure and makes communication impossible.

  The present invention has been made to solve such problems, and controls a signal characteristic variable device that changes a signal characteristic of a received signal in response to a change in attitude of an artificial satellite to move or generate an angle of a null point. The purpose is to expand the communicable angle region.

The satellite communication antenna device according to the present invention is
A communication antenna mounted on a satellite and facing the communication target directivity plane side at all times,
A communication antenna that is mounted on a satellite and faces the opposite direction surface of the communication target,
A signal characteristic variable device that is connected to each of the communication antennas and changes a signal characteristic of a reception signal output from each of the communication antennas;
A power multiplexer / demultiplexer that synthesizes the received signals output from each of the signal characteristic variablers and inputs them to a transceiver;
A control unit that detects received signal power output from the power multiplexer and controls at least one of the signal characteristic variablers based on a change in the received power due to a change in attitude of the satellite;

  According to the present invention, the received signal power of the power multiplexer / demultiplexer is detected, and based on the change in the received power due to the change in the attitude of the satellite, the angle of the null point is changed by changing the characteristics of the received signal by the signal characteristic variable device. The communicable angle region can be expanded by suppressing the movement or the occurrence thereof. Therefore, it is easy to secure a communication line, and it is possible to prevent communication from being interrupted. Moreover, since it is not the structure which uses a switch, there is no possibility of causing the failure of a switch.

Embodiment 1 FIG.
FIG. 1 is a diagram for explaining an operation example using the first embodiment. The communication target of the artificial satellite 1 is a ground station 3 installed on the earth 2. When the artificial satellite 1 is in the satellite orbit and faces the ground station 3, the artificial antenna 1 has the first antenna 4 and the second antenna 5 in the direction of the earth-oriented plane side 6 and the direction of the earth-reverse-oriented plane side 7, respectively. Mount the antenna so that it is placed in

  Here, a straight line connecting the artificial satellite 1 and the ground station 3 is defined as the Z axis. In the Z axis, the direction from the artificial satellite 1 to the ground station 3 is defined as a positive direction. When the artificial satellite 1 is used as a base point, the direction in which the ground station 3 can be seen, that is, the positive direction with respect to the Z axis is the earth-oriented surface side 6, and the negative direction with respect to the Z-axis is the earth reverse direction surface side 7. . Therefore, in this case, the communication target directivity surface side is the earth directivity surface side 6, and the communication target reverse directivity surface side is the earth reverse directivity surface side 7. By arranging in this way, the first antenna 4 arranged in the direction of the earth-oriented plane side 6 transmits and receives the RF signal 8 to communicate with the ground station 3.

  On the other hand, when the artificial satellite 1 is in the satellite orbit or when the artificial satellite 1 is rotated with respect to the ground station 3, the first antenna 4 is directed toward the earth reverse direction plane side 7. Sometimes. Therefore, in this case, there is the second antenna 5 in the direction of the earth-oriented surface side 6, and communication with the ground station 3 is performed with the second antenna 5.

  FIG. 2 is an internal block diagram of the satellite communication device 9 mounted on the artificial satellite 1 in the first embodiment. In FIG. 2, reference numeral 4 denotes a first antenna that is arranged on the earth directivity plane side 6 and transmits / receives an RF signal 8 to / from the ground station 3, and 5 is arranged on the earth reverse directivity plane side 7 and has the same function as the first antenna 4. Is a second antenna. The received signal output from the first antenna 4 is attenuated in power by a first power attenuator 10 having a function of attenuating power. The received signal output from the second antenna 5 is attenuated in power by a second power attenuator 11 having a function of attenuating power. The reception signals output from the first power attenuator 10 and the second power attenuator 11 are combined with the reception signal by the power multiplexer / demultiplexer 12.

  The combined received signal is input to the transmission / reception unit 13. The transmission / reception unit 13 includes a filter 14, a diplexer 15, a transmission unit 16, and a reception unit 17. The filter 14 attenuates a signal in a desired frequency band with respect to the reception signal output from the power multiplexer / demultiplexer 12. The diplexer 15 separates the transmission signal and the reception signal, and outputs the reception signal output from the filter 14 to the reception unit 17 at the time of reception. The receiving unit 17 demodulates the received signal output from the diplexer 15.

  At the time of transmission, the transmission unit 16 creates a transmission signal and the like and outputs it to the diplexer 15. The diplexer 15 separates the reception signal and the transmission signal and outputs the transmission signal to the filter 14. The filter 14 attenuates a signal in a desired frequency band. The power multiplexer / demultiplexer 12 demultiplexes the transmission signal so that the transmission signal output from the filter 14 is output from the first antenna 4 and the second antenna 5. The transmission signal output from the power multiplexer / demultiplexer 12 is output from the first antenna 4 and the second antenna 5 via the first power attenuator 10 and the second power attenuator 11.

  Further, the control unit 18 receives a signal for controlling the power attenuation amount of the first power attenuator 10 and the second power attenuator 11 from the ground station 3, and receives the first power attenuator 10 and the second power attenuator 10. A control signal for controlling the power attenuation amount of the power attenuator 11 is output.

  Here, the amplitude and phase of the electric field input to the first antenna 4 are Ap (θ) and φp (θ), and the amplitude and phase of the electric field input to the second antenna 5 are Am (θ) and φm ( θ). Here, θ is an angle formed with respect to the positive direction of the Z-axis, and θ = 0 ° when the first antenna 4 is facing the direction of the earth-oriented plane 6 and is directly facing the ground station 3. In addition, when the second antenna 5 is directed toward the earth-oriented plane side 6 and is directly facing the ground station 3, θ = ± 180 °.

  For example, the first power attenuator 10 does not attenuate the power, only the second power attenuator 11 attenuates the power, and the amplitude of the electric field output from the second antenna 5 is reduced by ΔAm (θ). Think about the case. At that time, as shown in FIG. 2, when the output of the first power attenuator 10 is point A, the output of the second power attenuator 11 is point B, and the output of the power multiplexer / demultiplexer 12 is point C, The electric fields at points A, B, and C are expressed as follows using a complex display (imaginary unit j).

  FIG. 3 is a power characteristic diagram in the case where the first power attenuator 10 and the second power attenuator 11 are not applied to the first antenna 4 and the second antenna 5, respectively. Is shown. In FIG. 3, the horizontal axis indicates the antenna viewing angle θ (deg), and the vertical axis indicates the relative power (dB). In FIG. 3, 19 indicates power at point A, 20 indicates power at point B, 21 indicates power at point C, and 22 indicates a null point.

  FIG. 3A is a power characteristic diagram in the case where the first power attenuator 10 and the second power attenuator 11 are not applied to the reception signals of the first antenna 4 and the second antenna 5. is there. FIG. 3B shows power characteristics when the first power attenuator 10 and the second power attenuator 11 are applied to the received signals of the first antenna 4 and the second antenna 5. FIG. Also, the communication line required power shown in FIGS. 3A and 3B indicates the power at the point C required for communication between the artificial satellite 1 and the ground station 3. Therefore, power lower than the communication line required power indicates that communication between the artificial satellite 1 and the ground station 3 is cut off.

  In order to explain FIG. 3, a description will be given based on FIG. 4, for example, corresponding to the attitude change of the artificial satellite 1 rotating with respect to the ground station 3. FIG. 4A shows a case where the first antenna 4 mounted on the artificial satellite 1 faces the earth-oriented surface side 6 and faces the ground station 3. At this time, θ = 0 ° as viewed from the Z-axis. Also in this case, the second antenna 5 is on the earth reverse direction plane side 7. FIG. 4B shows a case where the artificial satellite 1 starts to rotate and assumes an attitude of, for example, 0 ° <θ <90 ° as viewed from the Z axis. In this case, although the first antenna 4 is on the earth directivity plane side 6, it is tilted to the earth reverse direction plane side 7. In this case, the second antenna 5 is tilted to the earth-oriented surface side 6 although it is on the earth-inverted surface side 7.

  FIG. 4C shows a case where the artificial satellite 1 is further rotated and the first antenna 4 is in the posture of θ = 90 ° as viewed from the Z axis. Further, in this case, since the second antenna 5 is θ = −90 ° as viewed from the Z-axis, the received signals input to the first antenna 4 and the second antenna 5 as shown in FIG. The power is almost equal.

  FIG. 4D shows a case where the artificial satellite 1 further rotates and assumes an attitude of 90 ° <θ <180 ° as viewed from the Z axis. In this case, the first antenna 4 is inclined to the earth reverse direction plane side 7. The second antenna 5 is inclined toward the earth-oriented surface side 6. FIG. 4E shows a case where the artificial satellite 1 is further rotated and the first antenna 4 is directed to the earth reverse direction plane side 7 and has an attitude of θ = 180 ° as viewed from the Z axis. . In this case, communication with the ground station 3 is performed by the second antenna 5.

  As shown in FIG. 4A, when the first antenna 4 faces the ground station 3 and performs communication at θ = 0 °, the power 19 at point A in FIG. 3A is maximized. When the attitude of the artificial satellite 1 changes as time passes from FIG. 4B to FIG. 4D, the power 19 at point A in FIG. In FIG. 4E, that is, when θ = 180 °, the first antenna 4 is directed to the earth reverse direction plane side 7, and the power 19 at point A in FIG. 3A is minimum.

  On the other hand, since the second antenna 5 faces the direction of the earth reverse direction surface side 7, when FIG. 4A, that is, θ = 0 °, the power 20 at the point B in FIG. become. When the attitude of the artificial satellite 1 changes as time passes from FIG. 4B to FIG. 4D, the power 20 at point B in FIG. 3A increases. In FIG. 4 (e), that is, when θ = 180 °, the second antenna 5 is directed to the earth-oriented plane side 6, and therefore the power 20 at point B in FIG. 3 (a) is maximum.

  As the power 21 at point C in FIG. 3A, the power when the phases φp (θ) and φm (θ) of the received signals input to the first antenna 4 and the second antenna 5 differ by approximately 180 °. Is shown. When communicating with the ground station 3, as shown in FIG. 3 (a), the angle θ until the absolute value of θ is close to 90 ° centering on θ = 0 ° is the power 21 at the point C. Since the contribution of the received signal power at the antenna 4 is large, the communicable angle region of the first antenna is shown.

  Also, when the absolute value of θ is between 90 ° and 180 °, the power 21 at point C has a large contribution of the received signal power at the second antenna 5, and therefore indicates the communicable angle region of the second antenna. Yes. When the power from the first antenna 4 and the second antenna 5 is approximately equal, that is, when the absolute value of θ is near 90 °, both radio waves interfere with each other, a null point 22 is generated, and the power is extremely reduced. . This corresponds to the case where the attitude of the artificial satellite 1 is as shown in FIG. Therefore, as shown in FIG. 3 (a), communication is impossible at an angle θ where the power is reduced and the communication line required power is not satisfied.

  On the other hand, consider FIG. 3B, which is a power characteristic diagram when the output power of the second antenna 5 is attenuated by the second power attenuator 11. In this case, the absolute value of the angle θ at which the output signal powers of the first antenna 4 and the second antenna 5 are substantially equal is 90 ° in order to reduce the power from the point B as shown in FIG. A large angle.

  For example, a posture as shown in FIG. That is, since the first antenna 4 is facing the earth reverse direction plane side 7, the power 19 at the point A is further reduced as compared with the case where the absolute value of θ is 90 °. However, since the power 20 at the point B is reduced by the second power attenuator 11, the power 19 at the point A and the power 20 at the point B are substantially the same at an angle larger than θ = 90 °. . Therefore, the generation position of the null point 22 in the power C at the point C moves to an angle where the absolute value of θ is larger than 90 ° as shown in FIG.

  Thus, by attenuating the power from the second antenna 5, a relative difference is caused in the power from the first antenna 4 and the second antenna 5, and the position of the null point 22 is changed to the angle. It is moved in the direction that increases the absolute value of θ. As a result, the communicable angular area between the ground station 3 and the first antenna 4 of the artificial satellite 1 can be expanded as shown in FIG. Further, since this is not a configuration using a switch or the like, there is no possibility of inducing a switch failure.

  Further, when the first power attenuator 10 and the second power attenuator 11 are used, the transmission power of the artificial satellite 1 is too large, and the maximum reception power per unit area of the antenna in the ground station 3 is equal to or higher than a specified value. There is also an effect that the transmission power of the artificial satellite 1 can be attenuated and adjusted so that the antenna of the ground station 3 can be received.

  In the above description, the first power attenuator 10 does not attenuate the signal power, but only the second power attenuator 11 is used to attenuate the power output from the second antenna 5. However, even if both the first power attenuator 10 and the second power attenuator 11 attenuate the power, and the power 20 at the point B is relatively lowered as compared with the power 19 at the point A, the same applies. It goes without saying that the effect of can be obtained.

  Further, as can be seen from the description, the difference between the output signal powers of the first antenna 4 and the second antenna 5 causes the communicable angle region of the first antenna to increase in the absolute value of the angle θ. Therefore, instead of the first power attenuator 10 and the second power attenuator 11, the first power amplifier and the second power amplifier can be used.

  That is, if the first power amplifier and the second power amplifier are used to amplify the power at the point A relative to the power at the point B, the first power amplifier and the second power amplifier can be compared with the case where the power attenuator is used. It is possible to move the communicable angle region of one antenna in a direction in which the absolute value of the angle θ increases.

  Further, this satellite communication antenna device can be used for inter-satellite communication as shown in FIG. For example, as shown in FIG. 5, consider a case in which an artificial satellite 23 is located on the earth reverse direction plane side 7 with respect to the artificial satellite 1 communicating with the ground station 3. The artificial satellite 1 normally communicates with the ground station 3 using the first antenna 4 on the earth-oriented surface side 6. This corresponds to a case where the communication target of the artificial satellite 1 is the ground station 3 and the communication target directivity plane side is the earth directivity plane side 6. Accordingly, the received signal of the second antenna 5 is attenuated by the second power attenuator 11, and the null point 22 is moved in the direction in which the absolute value of the angle θ increases. Thereby, the communicable angle region of the first antenna is expanded.

  On the other hand, when the artificial satellite 1 communicates with the artificial satellite 23 on the earth reverse direction surface side 7, communication is performed using the second antenna 5 on the earth reverse direction surface side 7. This corresponds to a case where the communication target of the artificial satellite 1 is the artificial satellite 23 and the communication target directivity surface side is the earth reverse directivity surface side 7. Accordingly, the received signal of the first antenna 4 is attenuated by the first power attenuator 10, and the null point 22 is moved in the direction in which the absolute value of the angle θ becomes smaller. Thereby, the communicable angle area | region of a 2nd antenna is expanded.

  In the artificial satellite 1, when switching from the inter-satellite communication to the communication with the ground station 3, the command may be directly transmitted from the ground station 3 to the artificial satellite 1 as in the control of the power attenuator. Further, when the communicable angle region of the second antenna 5 is expanded, a control signal may be transmitted to the artificial satellite 1 via the artificial satellite 23 and switched.

  As described above, when performing communication with the ground station and inter-satellite communication, by changing the attenuation amounts of the first power attenuator 10 and the second power attenuator 11, the communicable angular region of the first antenna. Alternatively, since the communicable angle area of the second antenna can be expanded, it is possible to easily secure a communication line with the ground station and a line for satellite communication.

Embodiment 2. FIG.
FIG. 6 is an internal block diagram of the satellite communication device 9 mounted on the artificial satellite 1 in the second embodiment. In FIG. 6, the difference from the first embodiment is that the first phase delay unit 24 having a function of delaying the phase of the reception signal output from the first antenna 4 and the output from the second antenna 5 are used. A second phase delay unit 25 having a function of delaying the phase of the received signal, and a phase delay amount of the first phase delay unit 24 and the second phase delay unit 25 from the ground station 3 are controlled. The control unit 26 receives a signal and outputs a control signal for controlling the phase delay amount of the first phase delay unit 24 and the second phase delay unit 25.

  As in FIG. 2, the amplitude and phase of the electric field input to the first antenna 4 are Ap (θ) and φp (θ), and the amplitude and phase of the electric field input to the second antenna 5 are Am (θ), Let φm (θ).

  For example, when the first phase delayer 24 does not perform phase delay, only the second phase delayer 25 delays the phase, and the phase of the electric field output from the second antenna 5 is delayed by Δφm (θ). think of. At that time, as shown in FIG. 6, the point A that is the output of the first phase delayer 24, the point B that is the output of the second phase delayer 25, and the output of the power multiplexer 12. The electric field at point C is expressed as follows.

  FIG. 7 is a power characteristic diagram when the first phase delayer 24 and the second phase delayer 25 are not operated and when the first antenna 4 and the second antenna 5 are operated. Is shown. As in FIG. 3, in FIG. 7, the horizontal axis indicates the antenna viewing angle θ (deg), and the vertical axis indicates the relative power (dB). Similarly, 19 indicates power at point A, 20 indicates power at point B, 21 indicates power at point C, and 22 indicates a null point.

  FIG. 7A is a power characteristic diagram in the case where the first phase delay unit 24 and the second power attenuator 25 are not applied to the reception signals of the first antenna 4 and the second antenna 5. is there. FIG. 7B shows the power characteristics when the first phase delayer 24 and the second phase delayer 25 are applied to the received signals of the first antenna 4 and the second antenna 5. FIG. Further, the communication line required power shown in FIGS. 7A and 7B shows the power at the point C necessary for communication between the artificial satellite 1 and the ground station 3, as in FIG. Therefore, power lower than the communication line required power indicates that communication between the artificial satellite 1 and the ground station 3 is cut off.

  Since FIG. 7A is the same as FIG. 3A, the description thereof is omitted. On the other hand, consider FIG. 7B which is a power characteristic diagram when the phase of the output signal of the second antenna 5 is delayed by the second phase delay unit 25. For example, the phase difference between the reception signals output from the first antenna 4 and the second antenna 5 is adjusted, and the phase difference between the two signals is weakened and interfered to change to a strengthening phase difference. It can be seen that by changing the phase difference, the power C at the point C can suppress the occurrence of a null point at an arbitrary point as shown in FIG.

  In this way, by delaying the phase of the output signal of the second antenna 5, a relative difference is caused in the phase between the first antenna 4 and the second antenna 5, thereby suppressing the occurrence of a null point. It becomes possible to do. Thereby, as shown in FIG.7 (b), it becomes communicable by all the angles (theta) between the ground station 3 and the artificial satellite 1, and it does not interrupt communication. Further, in this case, since the switch is not configured using a switch or the like, there is no possibility of inducing a switch failure.

  In the above description, the first phase delayer 24 does not delay the phase, but only the second phase delayer 25 is used to delay the phase output from the second antenna 5. However, the same effect can be obtained if both the first phase delayer 24 and the second phase delayer 25 delay the phase and then change the phase at the point A and the phase at the point B to strengthen each other. It goes without saying that it can be obtained.

Embodiment 3 FIG.
In the first embodiment and the second embodiment, the ground station 3 transmits a signal for controlling the power attenuation amount of the power attenuator, the power amplification amount of the power amplifier, or the phase delay amount of the phase delay device, The signal is received by the artificial satellite 1, and the control unit 18 outputs a control signal for controlling the amount of power attenuation or power amplification, and the control unit 26 controls the phase delay amount. However, it is also possible to control inside the artificial satellite 1 by measuring the output of a power attenuator or the like.

  FIG. 8 shows a satellite in which the output power of the first power attenuator 10, the second power attenuator 11, and the power multiplexer / demultiplexer 12 is measured and the power attenuation is controlled using the control unit 27. 2 is a block diagram of a communication device 9. FIG. Since the control unit 27 is the same as that shown in FIG.

  FIG. 9 is a flowchart for explaining the operation of the control unit 27. The processing content will be described with reference to FIG. For example, the operation of the control unit 27 is started when the satellite is launched (step ST101). As shown in FIG. 8, the control unit 27 is configured such that the power at point A that is the output of the first power attenuator 10, the power at point B that is the output of the second power attenuator 11, and the power distribution. The power at point C, which is the output of the waver 12, is constantly measured.

  The measured power at point C is compared with, for example, power obtained by adding a certain amount of power to the communication line required power shown in FIG. 3 (hereinafter referred to as predetermined power) (step ST102). Here, the predetermined power may be set in advance in line design, ground test, or the like, or a signal may be transmitted from the ground station 3 to change the setting of the predetermined power.

  When the power at the point C exceeds the predetermined power, the control unit 27 does not output control signals for the first power attenuator 10 and the second power attenuator 11, and continues to measure the power at the point C. On the other hand, if the power at point C is lower than the predetermined power, the power at point A is compared with the power at point B (step ST103).

  When the power at the point A exceeds the power at the point B, the absolute value of the angle θ is 90 ° or less, indicating that it is in the communicable angle region of the first antenna. Therefore, the control signal is output from the control unit 27 to the second power attenuator 11 so as to attenuate the power at point B using the second power attenuator 11 (step ST104). This corresponds to the case of FIG. 3B and means that the null point 22 is moved in the direction in which the absolute value of the angle θ increases. In this case, as shown in FIG. 4B, the attitude of the artificial satellite 1 indicates that the angle θ increases as viewed from the Z axis and is tilted from the earth-oriented plane side 6. The attenuation amount is attenuated so that, for example, the communicable angle region of the first antenna is an angle where the absolute value of θ exceeds 0 ° to 90 °.

  Further, the power at point C is compared with a predetermined power (step ST105). Since the power at the point C increases by attenuating the power at the point B using the second power attenuator 11, the power at the point C exceeds the predetermined power when the power at the point B is initially attenuated. Should be. Therefore, the control unit 27 does not output control signals for the first power attenuator 10 and the second power attenuator 11, and continues to measure the power at point C.

  However, as time passes, the attitude of the artificial satellite 1 changes to the attitude shown in FIG. 4 (d) after passing through FIG. 4 (c), and the power at the point C falls below the predetermined power, as viewed from the Z axis. The angle θ is 90 ° or more. In this case, since the second antenna 5 is inclined toward the earth-oriented plane side 6, the second antenna 5 is used for communication with the ground station 3.

  Therefore, in order to perform communication between the second antenna 5 and the ground station 3, the attenuation amount of the second power attenuator 11 is set to 0, and the power at the point A is attenuated by the first power attenuator 10. (Step ST106). This means that, contrary to FIG. 3B, the null point 22 is moved in a direction in which the absolute value of the angle θ is 90 ° or less. This also means that the communicable angular area of the second antenna has been expanded.

  The control unit 27 continues to measure the power at point C when it is not forcibly terminated by an external command or the like (step ST107). However, when the control unit 27 is forcibly terminated, the control operation is terminated (step ST108).

  On the other hand, if the power at point A is lower than the power at point B in step ST103, the absolute value of the angle θ is 90 ° or more, indicating that the second antenna is in the communicable angle region. Therefore, using the first power attenuator 10, the control unit 27 outputs a control signal to the first power attenuator 10 so as to attenuate the power at point A (step ST109). Contrary to FIG. 3B, this means that the null point 22 is moved in a direction in which the absolute value of the angle θ is 90 ° or less. The attenuation amount is attenuated so that, for example, the communicable angle region of the second antenna is an angle where the absolute value of θ is less than 180 ° to 90 °.

  Further, the power at point C is compared with the predetermined power (step ST110). Since the power at the point C increases by attenuating the power at the point A using the first power attenuator 10, the power at the point C exceeds the predetermined power when the power at the point A is initially attenuated. Should be. Therefore, the control unit 27 does not output control signals for the first power attenuator 10 and the second power attenuator 11, and continues to measure the power at point C. However, with the passage of time, the attitude of the artificial satellite 1 changes to the attitude shown in FIG. 4B after passing through FIG. 4C, and when the power at the point C falls below the predetermined power, the angle as viewed from the Z axis θ is 90 ° or less. In this case, since the first antenna 4 is on the earth-oriented surface side 6, the first antenna 4 is used for communication with the ground station 3.

  Therefore, in order to perform communication between the first antenna 4 and the ground station 3, the attenuation amount of the first power attenuator 10 is set to 0, and the power at the point B is attenuated by the second power attenuator 11. (Step ST111). This means that the null point 22 is moved in the direction in which the absolute value of the angle θ is 90 ° or more, as shown in FIG. This also means that the communicable angular area of the first antenna has been expanded.

  By processing in this way, it becomes possible to control the attenuation amounts of the first power attenuator 10 and the second power attenuator 11 using the control unit 27 inside the artificial satellite 1.

  In order to prevent the communication line from being interrupted, the control unit 27 receives a signal from the ground station 3 and outputs a signal for controlling the attenuation amounts of the first power attenuator 10 and the second power attenuator 11. In addition, it may have a function of measuring power at points A, B, and C and outputting a signal for controlling the attenuation, and may have redundancy for preventing communication line interruption.

  In the description, the power at point A, point B, and point C is measured to control the attenuation amounts of the first power attenuator 10 and the second power attenuator 11. The first power attenuator 10 and the second power attenuation are mounted on the basis of the angle θ obtained by the angle sensor by mounting an angle sensor for obtaining the angle θ of the satellite 1 such as a star sensor, an earth sensor, or a gyro sensor. The amount of attenuation of the device 11 may be controlled.

  In the description, the case of the power attenuator has been described, but it goes without saying that the same control may be performed even in the case of the power amplifier. In the case of the phase delay device, when the power at the point C falls below a predetermined power, the power is output from the first antenna 4 and the second antenna 5 without comparing the power at the point A and the power at the point B. The occurrence of a null point may be suppressed at an arbitrary point by adjusting the phase difference of the received signal and changing the phase difference between the two signals to weaken and interfere with each other.

  In the first to third embodiments, the description has been given assuming that the number of antennas is two. However, the number of antennas may be two or more as long as there is at least one on the earth directing surface side and one or more on the earth reverse directing surface side. In that case, by placing a power attenuator in the subsequent stage of each antenna, the communicable angle region is changed by moving the null point, so the same effect as in the case of using two antennas can be obtained. Needless to say, a power amplifier or a phase delay may be used instead of the power attenuator.

  Although the above description is about the reception system, it goes without saying that the same effect can be obtained for the transmission system.

It is a figure explaining the example of operation using Embodiment 1 in the present invention. It is an internal block diagram of the satellite communication apparatus mounted in the artificial satellite of Embodiment 1 in this invention. It is a power characteristic figure which shows the effect of Embodiment 1 in this invention. It is a figure regarding the attitude | position of the artificial satellite for demonstrating the effect of Embodiment 1 in this invention. It is a figure explaining the communication between satellites using Embodiment 1 in this invention. It is an internal block diagram of the satellite communication apparatus mounted in the artificial satellite of Embodiment 2 in this invention. It is a power characteristic figure which shows the effect of Embodiment 2 in this invention. It is an internal block diagram of the satellite communication apparatus which mounts Embodiment 3 in this invention in the artificial satellite. It is a flowchart regarding the control part of Embodiment 3 in this invention.

Explanation of symbols

1. Artificial satellite2. Earth 3. Ground station4. First antenna 5. Second antenna 6. 6. Earth-oriented surface side Earth-reverse surface side 8. RF signal9. Satellite communication device 10. First power attenuator 11. Second power attenuator 12. Electric power multiplexer / demultiplexer 13. Transmitter / receiver 14. Filter 15. Diplexer 16. Transmitter 17. Receiving unit 18. Control unit 19. Power at point A20. Power at point B 21. Power at point C22. Null point 23. Artificial satellite 24. First phase delay 25. Second phase delay device 26. Control unit 27. Control unit

Claims (5)

A communication antenna mounted on a satellite and facing the communication target directivity plane side at all times,
A communication antenna that is mounted on a satellite and faces the opposite direction surface of the communication target,
A signal characteristic variable device that is connected to each of the communication antennas and changes a signal characteristic of a reception signal output from each of the communication antennas;
A power multiplexer / demultiplexer that synthesizes the received signals output from each of the signal characteristic variablers and inputs them to a transceiver;
A control unit that detects received signal power output from the power multiplexer / demultiplexer and controls at least one of the signal characteristic variable devices based on a change in the received power due to a change in attitude of the satellite; A satellite communication antenna device characterized by that. The controller is
When the received signal power output from the power multiplexer / demultiplexer does not satisfy a predetermined power,
The received signal power output from each of the signal characteristic variable devices is compared, and the communicable angle range of the antenna connected to the signal characteristic variable device determined to output a large received signal power is expanded. The satellite communication antenna apparatus according to claim 1, wherein at least one of the signal characteristic variable devices is controlled. Using a power attenuator as the signal characteristic variable device,
The controller is
When the received signal power output from the power multiplexer / demultiplexer does not satisfy a predetermined power,
The received signal power output from each of the power attenuators is compared, and at least the communication possible angle region of the antenna connected to the power attenuator determined to output a large received signal power is expanded. 3. The satellite communication antenna apparatus according to claim 1, wherein the power attenuator connected to a communication antenna facing a communication target reverse directivity surface is controlled. Using a power amplifier as the signal characteristic variable device,
The controller is
When the received signal power output from the power multiplexer / demultiplexer does not satisfy a predetermined power,
Comparing the received signal power output from each of the power amplifiers, at least the communication target so as to expand the communicable angle range of the antenna connected to the power amplifier determined to output a large received signal power 3. The satellite communication antenna apparatus according to claim 1, wherein the power amplifier connected to a communication antenna facing a directivity plane is controlled. A communication antenna mounted on a satellite and facing the communication target directivity plane side at all times,
A communication antenna that is mounted on a satellite and faces the opposite direction surface of the communication target,
A phase delay that is connected to each of the communication antennas and changes a phase characteristic of a reception signal output from each of the communication antennas;
A power multiplexer / demultiplexer that synthesizes the received signals output from each of the phase delayers and inputs the synthesized signals to the transceiver;
When the received signal power output from the power multiplexer / demultiplexer does not satisfy a predetermined power,
A satellite communication antenna apparatus comprising: a control unit that controls the phase delay so as to enable communication with a communication target regardless of the attitude of the satellite.

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