JP3339968B2 - Microwave power transmission equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for transmitting electric energy obtained by solar power generation or the like to a target object as a power receiving object such as a ground, a flying object, a space station or a space factory by a microwave. The present invention relates to a microwave power transmitting device.

[0002]

2. Description of the Related Art As a microwave power transmitting device, for example,
A solar power satellite launched from the earth into a geosynchronous orbit as a power generation device collects solar energy, converts the collected solar energy into microwaves using a microwave power transmission device, and transmits power to the microwave power transmission device. There is a method in which electric power is transmitted from a solar power generation satellite to a power receiving object by transmitting the microwave in an arrival direction of a pilot signal transmitted from the power receiving object using an antenna.

In such a microwave power transmitting device,
Unless the microwave beam is converged accurately on the power receiving antenna of the power receiving object during power transmission, the power transmission efficiency decreases, so the phase of the microwave to be transmitted is controlled and the microwave is transmitted to the pilot signal. A method called a retrodirective method, which is a type of phased array antenna, which enables transmission in the same direction as the direction of arrival, has been attempted.

[0004] In other words, the retrodirective method is
This is a method in which a conjugate phase shift from a pilot signal sent from a target object as a power receiving object is taken and power is directly transmitted to the power receiving object.

The principle of the retrodirective system will be described. In FIG. 3, a target point on the power receiving side where radio waves are to be concentrated is denoted by A, and a pilot signal having a frequency ω _i is radiated from the target point A toward the power transmitting side. And Further, in the power transmission side, which receives the pilot signal, and radiates toward the radio wave transmission becomes frequency omega _t to the target point A of the power receiving side. When the pilot signal emitted from the target point A, assuming that reaches the reference point P ₀ of the distance X ₀ apart transmitting side ₀ hours after t, the phase phi ₀ of the pilot signal at the reference point P ₀ is, phi ₀ = Ω _i (t ₀ −x ₀ / c) (1) Here, c is the speed of light.

Similarly, the phase φ ₁ at one point P ₁ on the power transmission side at a distance X ₁ from the target point A is φ ₁ = ω _i (t ₀ −x ₁ / c) (2) Therefore, the phase difference φ between the two points P ₀ and P _1
i is as follows: φ _i = φ ₁ −φ ₀ = −ω _i · r / c (3) However, if it is assumed that r = x ₁ −x ₀ radiate transmitted waves in phase from the two points P ₀ and P ₁ on the power transmission side, the phase difference between these transmitted waves received at the target point A is since the frequency of the radio wave is omega _t, becomes the equation _{(3), φ t = -ω t / c} (4). Therefore, in order to equalize the transmission wave of the phase from the two points P _0, P ₁ at the target point A, the transmission wave of the phase emitted from the point _{P 1, φ c = ω t} · r / c (5 You only have to compensate. That is, the reference point P ₀ on the power transmission side
By performing the phase compensation of equation (5) at points other than the above, the phases of all transmitted radio waves emitted from the power transmission side become equal at the target point. This is the principle of the retrodirective system. As a microwave transmission device adopting the above-described retrodirective method, for example, Japanese Patent Application No.
No. 259205 and the drawings.

FIG. 4 shows the configuration of this microwave power transmitting device.

In FIG. 4, a receiving circuit 102 amplifies or attenuates a pilot signal received by a receiving antenna 103 to a predetermined level, and outputs the obtained signal to a phase conjugate circuit 112. Phase conjugate circuit 112
Generates a reference microwave signal having an n-fold frequency conjugate in phase with the input pilot signal and outputs the signal to the demultiplexing circuit 113. The receiving circuit 102, as shown in FIG.
Usually, it comprises a band-pass filter 123 that allows only the frequency band of the pilot signal to pass, and an AGC amplifier 124 that is used to vary the gain and keep the level of the output signal constant with respect to fluctuations in the input signal level.

Here, assuming that the phase of the input signal at the power transmitting side reference point P ₀ shown in FIG. 3 is ω _i · t, the phase φ _{i at the} point P ₁ is given by the following equation (3): φ _i = ω _i · t−ω _i · r / c = ω _i (t−r / c) (6) The phase φ of the output signal after compensating the phase at the point P ₁ must be given by the following equation (5): φ = ωt · t−ωt · r / c = ωt (t + r / c) (7) That is, the phase conjugate circuit 112
Sets the phase φ _{i of the} pilot signal shown in the equation (6) to (7)
Is converted to the phase φ shown in the equation.

[0010] The demultiplexing circuit 113 demultiplexes the input reference microwave signal into n variable phase shifters 114a and 114.
, 114n. The variable phase shifter 114
a,. . . , N are n antenna elements 120a, 120b,..., Of a plurality of divided sub-array power transmitting antennas.
120n respectively.

On the other hand, receiving circuits 115 to 117 amplify or attenuate pilot signals received by receiving antennas 104 to 106 to a predetermined level and output the signals to angle detecting circuit 118.

The angle detecting circuit 118 includes an RF interferometer, and determines the direction of the power receiving object by measuring the phase difference between pilot signals received by the three receiving antennas 104 to 106, and obtains an angle signal indicating the direction. To the processing unit 1
Output to 19.

The arithmetic processing unit 119 includes a microcomputer, and based on the input angle signal, each of the antenna elements 120a, 120b,.
, 114n by calculating the phase difference of the microwaves such that the microwaves output from 0n converge on a power receiving antenna (not shown) of the power receiving object.
Output to Variable phase shifters 114a, 114b, ..., 11
4n respectively generate a phase difference in the reference phase microwave input from the demultiplexing circuit 113 according to the phase difference signal input from the arithmetic processing circuit 119, and
21a, 121b,..., 121n.

The power amplifiers 121a, 121b,..., 12
1n is each antenna element 120a, 12a of the power transmission antenna.
0b,..., 120n, respectively, and converts the power supplied from the external power supply 122 into the variable phase shifters 114a,
, 114n are amplified to microwaves having the phase and frequency of signals output from the power transmitting antennas, and output to the antenna elements 120a, 120b,..., 120n of the power transmission antenna.

[0015] Each antenna element 120a,
Each of 120b,..., 120n radiates a microwave having a power-amplified phase difference toward a target object on the power receiving side.

The receiving antenna 103 and the receiving circuit 10
2, the phase conjugate circuit 112, the demultiplexing circuit 113, and the variable phase shifters 114a, 114b,..., 114n constitute a phase control unit, and the receiving antennas 104 to 106 and the receiving circuit 115
To 117, the angle detection circuit 118 and the arithmetic processing circuit 11
9 constitutes a signal processing unit.

By transmitting power using the above-described microwave power transmitting device, the directivity of the microwave beam is improved, and as a result, efficient power transmission becomes possible.

[0018]

However, in such a conventional microwave power transmitting device, the pilot signal from the power receiving object becomes weak due to an increase in the distance between the power receiving object and the microwave power transmitting device. In such a case, the level of the input signal to the AGC amplifier 124 may be out of the operating range of the AGC amplifier 124. In such a case, the level of the output signal from the AGC amplifier 124 decreases, and as a result, the power Amplifiers 121a, 121
b,..., 121n are input to the power amplifier 12
Since the input signal levels of the input signals 1a, 121b,..., 121n are outside the range that can be linearly amplified, the power amplifiers 121a, 121b,.
.., 121n perform nonlinear operations and generate harmonics.

The power amplifiers 121a and 121a
, 121n, the FE used for the power amplifiers 121a, 121b,.
Promotes the deterioration of T.

Further, power transmission with harmonics generated has a problem in that the power supply at that time is wasted in space because the power supply is limited.

Further, there is a problem that generation of harmonics cannot comply with spurious emission regulations (50 dBc or less of a fundamental wave), and it has been a problem to solve these problems.

[0022]

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a microwave power transmission device which does not generate harmonics and has high power transmission efficiency.

[0023]

According to the present invention, there is provided a microwave power transmitting apparatus comprising: a plurality of receiving antennas for receiving a pilot signal having a predetermined frequency transmitted from a power receiving object;
A receiving circuit provided with an AGC amplifier for amplifying or attenuating a pilot signal received by a receiving antenna to a fixed level, and a frequency conjugated to the pilot signal output from the receiving circuit and having a phase conjugate with n times the pilot signal A phase conjugate circuit that generates the signal of the following, an angle detection circuit that detects the direction of arrival of the pilot signal, and a microwave transmitted from the power transmission antenna based on the signal that represents the direction of arrival of the pilot signal output from the angle detection circuit. An arithmetic processing unit for calculating a phase difference focused on the power receiving object, a variable phase shifter for generating a phase difference in a signal output from the phase conjugate circuit by a signal output from the arithmetic processing unit, and an externally supplied A power amplifier that amplifies the applied power to a microwave having a phase and frequency of a signal output from the variable phase shifter; and In the microwave power transmitting device basically configured by the power transmitting antenna that transmits the microwave output from the width unit to the power receiving object, when the level of the signal input to the power amplifier is lower than a predetermined level, The present invention is characterized in that a bias control circuit for cutting a DC bias applied to the power amplifier is provided.

In an embodiment of the microwave power transmitting apparatus according to the present invention, the output of the AGC amplifier in the receiving circuit is used to determine whether the signal level of the signal input to the power amplifier is lower than a predetermined level. It is possible to adopt a configuration in which the envelope detection is performed and the determination is made based on the level of the DC signal converted to DC.

[0025]

The microwave power transmitting device according to the present invention has the above-described configuration, and is a microwave power transmitting device for transmitting electric energy using a retrodirective method to a target object as a power receiving object by microwaves. When the level of the input signal is smaller than a predetermined level, that is, when the input signal level is out of the range of the input signal level that can be linearly amplified by the power amplifier, a bias control circuit that cuts a DC bias applied to the power amplifier is provided. As a result, the power amplifier does not operate nonlinearly to generate harmonics. As a result, unnecessary power is not consumed, and the F
Deterioration of the ET is not promoted, and the spurious emission regulation (50 dBc or less of the fundamental wave) is achieved.

Here, in order to determine whether or not the signal level of the signal input to the power amplifier is lower than a predetermined level, a DC signal obtained by performing envelope detection on the output of the AGC amplifier in the receiving circuit and converting the signal into a DC signal is used. In this configuration, the pilot signal is a high-frequency signal. Therefore, a new detecting device must be added to detect the signal level.

However, when the AGC amplifier of the receiving circuit amplifies or attenuates the level of the input signal to generate an output signal having a constant gain, the rate of amplification or attenuation is controlled in accordance with the magnitude of the output signal. And an AGC control circuit for keeping the magnitude of the output signal constant.
In the C control circuit, when judging the magnitude of the output signal, the output of the AGC amplifier is envelope-detected and a DC signal is fed back to control the amplification or attenuation ratio based on this information. Therefore, the output of the AGC amplifier is envelope-detected, the DC signal converted into a DC signal is demultiplexed and input to the bias control circuit, and the DC signal in the bias control circuit has an input signal level that can be linearly amplified by the power amplifier. It is determined whether it is within the range, and when it is outside the range, the DC bias is cut, and as described above, generation of harmonics is suppressed.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the microwave power transmitting device according to the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the microwave power transmitting device according to the present invention.

In FIG. 1, receiving antennas 1, 2, 3, and 4 for receiving a pilot signal transmitted from a power receiving object (not shown) are provided for one power transmitting antenna element 14 of a plurality of power transmitting antennas. In addition, the power transmission antenna is formed by collecting a plurality of power transmission antenna elements 14.

The pilot signal of frequency f ₀ (for example, 8 GHz) received by the receiving antenna 1 is input to the receiving circuit 5.

The receiving circuit 5 is basically composed of a band-pass filter 6 and an AGC amplifier 7, and the band-pass filter 6 is a filter for passing only the frequency band of the pilot signal.
Is output to the AGC amplifier 7.

The AGC amplifier 7 amplifies or attenuates an input pilot signal to a signal having a predetermined amplitude. As shown in FIG. Variable amplifier / attenuator 8 for amplifying or attenuating the pilot signal and the rate of amplification or attenuation of variable amplifier / attenuator 8 according to the magnitude of the output signal from variable amplifier / attenuator 8 to control the output signal. An AGC control circuit 9 for keeping the size constant is provided. This is to keep the input level to the power amplifier 13 constant.

The AGC control circuit 9 variably amplifies and direct-converts the direct-current DC signal by envelope detection of the output of the AGC amplifier 7.
The variable amplifier / attenuator 8 controls the rate of amplification or attenuation based on this information by feeding back to the attenuator 8 and controls the output of the AGC amplifier 7 to be constant.

The output signal from the AGC amplifier 7 shown in FIG.
This is a DC signal obtained by performing envelope detection on the output of the AGC amplifier 7 in the control circuit 9 and converting the output to DC. This DC signal is input to the bias control circuit 10.

The phase conjugate circuit 11 generates a reference microwave signal having an n-fold frequency whose phase is conjugate to the signal input from the AGC amplifier 7 and outputs the signal to the variable phase shifter 12.

The bias control circuit 10 determines whether the DC signal input from the AGC control circuit 9 is smaller than a predetermined level, that is, whether or not the input signal level is within a range in which the power amplifier 13 can perform linear amplification. , Power amplifier 1
3, the power amplifier 1
3 is sent to the power amplifier 13 to instruct to cut the DC bias. Alternatively, a circuit having a function of cutting the DC bias of the power amplifier 13 can be provided in a part of the bias control circuit 10.

On the other hand, the remaining three receiving antennas 2, 3,
Reference numeral 4 denotes a receiving circuit for receiving the pilot signals.
Output to 5,16,17.

The receiving circuits 15, 16 and 17 amplify or attenuate the pilot signal to a predetermined level and output it to the angle detecting circuit 18. The receiving circuits 15, 16, 1
The configuration of 7 is the same as the configuration of the receiving circuit 5.

The angle detecting circuit 18 includes an RF interferometer, and determines the direction of the power receiving object by measuring the phase difference between the pilot signals received by the three receiving antennas 2 to 4, and obtains the angle signal indicating the direction. Is output to the arithmetic processing unit 19.

The arithmetic processing unit 19 includes a microcomputer, and the microwave output from the antenna element 14 of the power transmitting antenna converges on the power receiving antenna of the power receiving object based on the angle signal input from the angle detecting circuit 18. The phase difference of the microwave is calculated and the variable phase shifter 12
Output to

Each of the variable phase shifters 12 generates a phase difference in the reference phase microwave input from the phase conjugate circuit 11 according to the phase difference signal input from the arithmetic processing unit 19, and outputs the microwave to the power amplifier 13. .

The power amplifier 13 amplifies the power supplied from the external power supply 20 into a microwave having the phase and frequency of the signal output from the variable phase shifter 12 and outputs the amplified microwave to the antenna element 14 of the power transmission antenna. When a signal for instructing to cut the DC bias is input from the circuit, the signal is not output.

Each of the antenna elements 14 of the power transmitting antenna radiates a microwave having a frequency n · f ₀ having a phase difference subjected to power amplification toward a power receiving object.

Therefore, in this embodiment, since the DC signal in the AGC control circuit 9 corresponding to the signal level of the pilot signal is input to the bias control circuit 10, the signal level of the pilot signal is If the signal level falls below a predetermined level due to a cause such as the distance from the power amplifier 13 being increased, the bias control circuit 10 determines that the signal level of the pilot signal is below the predetermined level and cuts the DC bias of the power amplifier 13. Since the output of the power amplifier 13 is turned off, generation of harmonics in the power amplifier 13 can be prevented.

The microwave power transmitting device shown in FIG. 1 has a configuration in which four receiving antennas 1, 2, 3, and 4 are provided for one power transmitting antenna element 14.
As in the microwave power transmitting device shown in FIG. 3, four receiving antennas 1, 2, 3, 4 for a plurality of antenna elements 14 are provided.
Needless to say, it is also possible to adopt a configuration in which

[0046]

As described above, the microwave power transmitting apparatus according to the present invention has the above-described configuration, and transmits microwave energy to a target object as a power receiving object by applying microwave energy to the retrodirective system. In the power transmission device, when the level of the signal input to the power amplifier is lower than a predetermined level, that is, when the level of the input signal level that can be linearly amplified by the power amplifier is out of the range, the DC bias applied to the power amplifier is reduced. By providing a bias control circuit for cutting, it is possible to prevent the power amplifier from performing a non-linear operation and generating harmonics, thereby suppressing wasteful power consumption,
Acceleration of deterioration of the FET used in the power amplifier can be prevented.

Further, since no harmonic is generated, the spurious emission regulation (50 dBc or less of the fundamental wave) can be achieved.

Further, the magnitude of the DC signal corresponding to the signal level of the pilot signal in the AGC control circuit is determined in the bias control circuit as to whether or not this DC signal is within the range of the input signal level at which the power amplifier can linearly amplify. Therefore, an effect is obtained that the operation can be performed relatively easily without adding a new device.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of an embodiment of a microwave power transmitting device according to the present invention.

FIG. 2 shows an AG in the microwave power transmitting device according to the present invention.
FIG. 3 is an explanatory diagram showing a basic configuration in a C amplifier.

FIG. 3 is an explanatory diagram illustrating the principle of a retrodirective system in a microwave power transmitting device.

FIG. 4 is an explanatory diagram illustrating a configuration of a conventional microwave power transmission device.

FIG. 5 is an explanatory diagram illustrating a configuration of a receiving circuit in a conventional microwave power transmitting device.

[Explanation of symbols]

 1-4 Receiving antenna 5 Receiving circuit (phase control unit side) 6 Band pass filter 7 AGC amplifier 8 Variable amplifying / attenuator 9 AGC controlling circuit 10 Bias controlling circuit 11 Phase conjugate circuit 12 Variable phase shifter 13 Power amplifier 14 Power transmitting antenna element 15-17 Receiving circuit (signal processing unit side) 18 Angle detection circuit 19 Operation processing unit 20 External power supply

Continuation of the front page (56) References JP-A-4-112635 (JP, A) JP-A-57-97704 (JP, A) JP-A-59-218008 (JP, A) JP-A-59-188202 (JP, A) JP-A-6-196921 (JP, A) JP-A-63-166305 (JP, A) JP-A-6-327172 (JP, A) JP-A-63-217702 (JP, A) 1-16047 (JP, B2) Japanese Patent Publication No. 3-11562 (JP, B2) US Patent 5,686,669 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02J 17/00 H01Q 3 / 26 G01S 7/00-7/66

Claims (2)

(57) [Claims] A plurality of receiving antennas for receiving a pilot signal having a predetermined frequency transmitted from a power receiving object;
A receiving circuit provided with an AGC amplifier for amplifying or attenuating a pilot signal received by a receiving antenna to a fixed level, and a frequency conjugated to the pilot signal output from the receiving circuit and having a phase conjugate with n times the pilot signal A phase conjugate circuit that generates the signal of the following, an angle detection circuit that detects the direction of arrival of the pilot signal, and a microwave transmitted from the power transmission antenna based on the signal that represents the direction of arrival of the pilot signal output from the angle detection circuit. An arithmetic processing unit that calculates a phase difference focused on the power receiving object, a variable phase shifter that generates a phase difference in a signal output from the phase conjugate circuit by a signal output from the arithmetic processing unit, A power amplifier that amplifies the applied power to a microwave having a phase and frequency of a signal output from the variable phase shifter; and In the microwave power transmitting device basically configured by the power transmitting antenna that transmits the microwave output from the width unit to the power receiving object, when the level of the signal input to the power amplifier is lower than a predetermined level, A microwave power transmission device comprising a bias control circuit for cutting a DC bias applied to a power amplifier. 2. A method for determining whether a signal level of a signal input to a power amplifier is lower than a predetermined level.
2. The microwave power transmitting device according to claim 1, wherein the output of the AGC amplifier in the receiving circuit is envelope-detected and determined based on a level of a DC signal converted into a DC signal.