JP7655541B2 - Phased Array Antenna - Google Patents

Description

The present invention relates to a phased array antenna that transmits and receives circularly polarized waves.

In the fifth generation (5G) communications aimed at achieving high-speed, large-capacity communications, research is being conducted into communications using circularly polarized waves in mobile and satellite communications. Circularly polarized waves are those in which the direction of the electric field rotates in a plane perpendicular to the direction of propagation of the electromagnetic wave at a period equal to the excitation frequency.

When satellite communication is performed using wireless communication with linearly polarized waves, either horizontally or vertically polarized waves, the polarization direction changes depending on the satellite's attitude, and the polarization plane cannot be determined, making it difficult to receive signals. In contrast, satellite communication using wireless communication with circular polarization has the characteristic that signals can be received without determining the polarization plane.

Non-Patent Document 1 describes a phased array antenna that transmits and receives circularly polarized waves. This phased array antenna has multiple antenna elements that transmit and receive circularly polarized waves. In this phased array antenna, each antenna element has a first port for inputting a first signal, and a second port for inputting a second signal that has a phase difference of +90° or -90° with respect to the first signal.

Salvatore Liberto, George Goussetis, Nakul Haridas “Dual Circular Polarization Receive Antenna Element for Ka-Band Satellite Communications” 2020 International Conference on UK-China Emerging Technologies (UCET), IEEE: 29 Sep 2020 Glasgow, UK

When transmitting beamformed circularly polarized waves in a set band using the phased array antenna described in Non-Patent Document 1, the amount of isolation between the first and second ports changes depending on the beam angle (Non-Patent Document 1, Fig. 7), and the polarization accuracy of the generated circularly polarized waves deteriorates due to the change in the 90° phase difference between the first and second signals, resulting in a decrease in antenna gain and a decrease in communication speed.

The present invention aims to provide a phased array antenna that can improve polarization accuracy when beamforming and transmitting circularly polarized waves.

One aspect of the present invention is a phased array antenna comprising: an antenna element having a first port for inputting a first signal and a second port for inputting a second signal having a phase difference of +90° or -90° with the first signal, the first signal and the second signal being combined to generate and transmit a circularly polarized wave; an antenna unit provided with a plurality of the antenna elements; and a control circuit that individually controls each of the antenna elements to adjust the beam direction of the circularly polarized wave radiated from the antenna unit, and adjusts the phase difference and amplitude difference between the first signal and the second signal according to the beam direction.

According to the present invention, the control circuit adjusts the phase difference and amplitude difference between the first signal and the second signal according to the beam direction, thereby improving the polarization accuracy and improving the antenna gain when transmitting a circularly polarized wave by beamforming.

The control circuit of the present invention may also include a first circuit that generates the first signal and the second signal with the phase shift amount adjusted based on a transmission signal, a second circuit that adjusts the phase, amplitude, and output of the first signal and the second signal and outputs them individually at each of the antenna elements, and a third circuit that detects the phase and amplitude between the first signal and the second signal in the second circuit and adjusts the phase difference and the amplitude difference based on the detection result.

In addition, according to the present invention, the third circuit adjusts the phase difference and amplitude difference between the first signal and the second signal, thereby adjusting the error in the amount of isolation between the first port and the second port that occurs when a circularly polarized signal is beamformed and transmitted, thereby improving the polarization accuracy of the signal radiated from the antenna unit 2 and improving the communication speed.

The third circuit of the present invention may also calculate the phase difference and the amplitude difference between the first signal and the second signal based on the detection results of the first power of the first signal, the second power of the second signal, and the third power obtained by combining the first power and the second power, and adjust the phase difference and the amplitude difference based on the calculation results.

According to the present invention, the provision of the third circuit makes it possible to adjust the phase difference and amplitude difference between the first signal and the second signal that occurs during beamforming of circularly polarized waves, and to adjust and reduce the error in the amount of isolation that occurs between the first port and the second port.

The present invention also includes a fourth circuit that applies a first initial adjustment amount to the phase and amplitude of the first signal and the second signal in the first circuit based on the detection result of the initial value of the circularly polarized wave output from the antenna element.

According to the present invention, the fourth circuit is provided, so that the initial values of the phase and amplitude errors between the first signal and the first signal generated in the first circuit can be adjusted.

The present invention makes it possible to improve polarization accuracy when beamforming and transmitting circularly polarized waves.

1 is a diagram illustrating a schematic configuration of a phased array antenna according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a schematic configuration of a first circuit and a fourth circuit. FIG. 4 is a diagram illustrating a schematic configuration of a second circuit and a third circuit. FIG. 13 is a diagram illustrating a schematic configuration of a detection unit of a third circuit. FIG. 1 is a block diagram showing a configuration of a phased array antenna.

The phased array antenna 1 shown in FIG. 1 is an antenna device that transmits and receives by controlling the beam direction of circularly polarized waves. The configuration of the transmitting side of the transmission signal in the phased array antenna 1 will be described below. The phased array antenna 1 includes, for example, an antenna section 2 provided with multiple antenna elements 3, and a control circuit 10 that controls the transmission and reception of circularly polarized waves in the antenna section 2. The antenna section 2 includes, for example, multiple n×m (n, m: natural numbers) antenna elements 3 arranged therein. The antenna elements 3 are, for example, patch antennas.

The antenna element 3 has, for example, a first port 4 for inputting a first signal having a predetermined excitation frequency, and a second port 5 for inputting a second signal having a phase difference of +90° or -90° with the first signal. When the first signal and the second signal are combined in the antenna element 3, the direction of the electric field rotates in a plane perpendicular to the traveling direction of the electromagnetic wave with a period equal to the excitation frequency, and a circularly polarized wave is generated and transmitted. The antenna unit 2 is connected to, for example, a control circuit 10 for generating a transmission signal.

The control circuit 10, for example, controls the transmission and reception of a circularly polarized signal. The control circuit 10, for example, generates a transmission signal to be transmitted and converts the transmission signal into a circularly polarized wave. The control circuit 10 can generate, for example, a right-handed circularly polarized wave or a left-handed circularly polarized wave. The control circuit 10, for example, individually controls each antenna element to adjust the beam direction of the circularly polarized transmission signal radiated from the antenna unit 2. The control circuit 10, for example, includes a first circuit 11 that generates a transmission signal based on a digital signal, and a second circuit 12 that performs analog adjustment of the transmission signal generated by the first circuit 11 and outputs it to each antenna element.

The first circuit 11 is connected to a fourth circuit 13 that adjusts the phase and amplitude of the first and second signals based on the signal output from the antenna unit 2. The second circuit 12 is provided with a third circuit 14 (described below) that detects the phase difference and amplitude difference between the first and second signals and adjusts the phase difference and amplitude difference based on the detection result.

The first circuit 11 generates a transmission signal having a frequency set based on a digital signal to be transmitted. Based on the generated transmission signal, the first circuit 11 generates a first signal with an adjusted phase shift amount for generating a circularly polarized wave, and generates a second signal having a phase difference of +90° or -90° compared to the first signal. For example, the first circuit 11 generates the first signal with a phase difference of 0° compared to the transmission signal. For example, the first circuit 11 generates the second signal with a phase difference of +90° or -90° compared to the transmission signal. When generating a right-handed circularly polarized wave, the first circuit 11 generates a second signal with a phase difference of +90° compared to the first signal, and when generating a left-handed circularly polarized wave, the first circuit 11 generates a second signal with a phase difference of -90° compared to the first signal. The first circuit 11 outputs the generated first and second signals to the adjacent fourth circuit 13.

As shown in FIG. 2, the fourth circuit 13 adjusts the phase and amplitude of the first signal and the second signal generated by the first circuit 11. The fourth circuit 13 applies a first initial adjustment amount to the phase and amplitude of the first signal and the second signal in the first circuit 11 based on the detection result of the initial value of the circularly polarized wave output from the antenna element 3 (antenna unit 2).

The first initial adjustment amount is an adjustment value that is set as an initial value to measure the signal output from the antenna element 3 using a receiving antenna and adjust the phase and amplitude error between the measured value and the first signal and the second signal generated by the first circuit 11. The first initial adjustment amount is set, for example, by first measuring the signal radiated from the antenna section 2 of the completed phased array antenna 1 using an externally installed receiving antenna (not shown).

The receiving antenna, for example, measures a signal with a beam angle of 0° radiated from the antenna unit 2. The measured value is used to calculate the phase and amplitude errors of the first and second signals. Based on the calculated error, a first initial adjustment amount is calculated to be applied to the first and second signals output from the first circuit 11. The calculated first initial adjustment amount is set as a fixed value in the fourth circuit 13. The fourth circuit 13 outputs the first and second signals to which the first initial adjustment amount has been applied.

Figure 3 shows an antenna unit 12U constituting the second circuit 12. The second circuit 12 includes a plurality of antenna units 12U. The plurality of antenna units 12U are circuits that control the transmission of signals for each of a predetermined number of antenna elements 3. That is, the second circuit 12 adjusts the first signal and the second signal individually for each antenna unit 12U. In the example of Figure 3, the antenna unit 12U controls four antenna elements 3 simultaneously. The antenna unit 12U may control four or more antenna elements 3 simultaneously, or may control each antenna element 3 individually.

The antenna unit 12U, for example, has four antenna circuits 12Up (p=1-4) connected to four antenna elements 3, respectively. The antenna unit 12U has a first input section 12V to which a first signal is input, and a second input section 12H to which a second signal is input. The input first and second signals are input to a distribution circuit 12B. The distribution circuit 12B amplifies and distributes the first and second signals to each antenna circuit 12Up. The antenna circuit 12Up, for example, performs analog conditioning on the first and second signals and outputs them to the antenna elements 3.

The antenna circuit 12Up includes a phase adjuster 12UF1 that adjusts the phase of the first signal, an amplitude adjuster 12US1 that adjusts the amplitude of the first signal, and an amplifier 12UP1 that amplifies the first signal. The antenna circuit 12Up includes a first connection part Vp that connects to the first port 4 at the connection part with the antenna element 3. The phase, amplitude, and output of the first signal are adjusted via the phase adjuster 12UF1, the amplitude adjuster 12US1, and the amplifier 12UP1, and the first signal is output from the first port 4 via the first connection part Vp.

The antenna circuit 12Up includes a phase adjuster 12UF2 that adjusts the phase of the second signal, an amplitude adjuster 12US2 that adjusts the amplitude of the second signal, and an amplifier 12UP2 that amplifies the second signal. The antenna circuit 12Up includes a second connection part Hp that connects to the second port 5 at the connection part with the antenna element 3. The second signal has its phase, amplitude, and output adjusted via the phase adjuster 12UF2, the amplitude adjuster 12US2, and the amplifier 12UP2, and is output from the second port 5 via the second connection part Hp.

With the above configuration, the antenna unit 12U amplifies, adjusts the phase, and adjusts the amplitude of the first and second signals. The second circuit 12 controls the first and second signals for each of the multiple antenna units 12U to generate circularly polarized waves in the antenna element 3. The second circuit 12 generates circularly polarized waves with a phase difference for each of the multiple antenna units 12U, and adjusts the beam direction of the signal radiated from the antenna section 2.

As described above, when a circularly polarized signal beam is radiated from the antenna unit 2, the relationship of the distance and position between the first and second ports changes depending on the beam angle, changing the amount of isolation between the two ports, and changing the phase difference and amplitude difference of +90° or -90° between the first and second signals. The second circuit 12 includes, for example, a third circuit 14 that adjusts the phase and amplitude between the first and second signals depending on the beam direction of the circularly polarized signal radiated from the antenna unit 2.

The third circuit 14 detects the phase difference and amplitude difference between the first signal and the second signal in the second circuit 12, and adjusts the phase difference and amplitude difference between the first signal and the second signal based on the detection result. The third circuit 14 includes, for example, a detection unit 15 connected to the first connection part Vp and the second connection part Hp, a first phase amplitude adjustment unit 16 provided in the first input part 12V, and a second phase amplitude adjustment unit 17 provided in the second input part 12H.

The detector 15 detects the phase difference and the amplitude difference between the first signal and the second signal at the first connection part Vp and the second connection part Hp. A detector 15 is provided in each antenna circuit 12Up, but only one detector 15 is actually operating in the antenna unit 12U. The other detectors 15 are used as backups.

The first phase and amplitude adjustment unit 16 of the third circuit 14 adjusts the phase and amplitude of the first signal input from the first input unit 12V based on the detection result by the detection unit 15. The second phase and amplitude adjustment unit 17 adjusts the phase and amplitude of the second signal input from the second input unit 12H based on the detection result by the detection unit 15.

As shown in FIG. 4, the detection unit 15 includes a first switch 15A provided at the first connection part Vp, a second switch 15B provided at the second connection part Hp, a power combiner 15C connected to the first switch 15A and the second switch 15B, and a detection circuit 15D connected to the power combiner 15C. The first switch 15A turns on/off the connection between the first connection part Vp and the power combiner 15C. The second switch 15B turns on/off the connection between the second connection part Hp and the power combiner 15C.

The detection circuit 15D turns on the first switch 15A and detects the first power of the first signal input to the power combiner 15C. The detection circuit 15D turns on the second switch 15B and detects the second power of the second signal input to the power combiner 15C. The detection circuit 15D turns on the first switch 15A and the second switch 15B simultaneously. The power combiner 15C generates a third power by combining the input first power and second power. The detection circuit 15D detects the third power combined by the power combiner 15C.

Because the first power of the first signal and the second power of the second signal have a phase difference of +90° or -90°, the third power when there is no error is √2 times the first power and the second power. The antenna unit 12U calculates the phase difference and amplitude difference between the first signal and the second signal based on the detection results of the first power of the first signal and the second power of the second signal in the detection circuit 15D. The antenna unit 12U adjusts the phase difference and amplitude difference between the first signal and the second signal based on the calculation results.

As shown in FIG. 5, the phased array antenna 1 includes a control unit 10C that controls the control circuit 10, and a storage unit 10M that stores data and programs used in the control. The control unit 10C comprehensively controls each control circuit in the control circuit 10 based on the data and programs stored in the storage unit 10M, for example, to generate a signal and control the beam direction of the signal radiated from the antenna unit 2.

The control unit 10C is realized by, for example, a hardware processor such as a CPU (Central Processing Unit) executing a program (software). Some or all of these components may be realized by hardware (including circuitry) such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a GPU (Graphics Processing Unit), or may be realized by a combination of software and hardware. The program may be stored in advance in a storage device such as an HDD (Hard Disk Drive) or flash memory that the storage unit 10M has, or may be stored in a removable storage medium such as a DVD or CD-ROM, and installed by mounting the storage medium in a drive device. In addition, the program is not necessarily required, and a predetermined operation may be executed by configuring a sequential circuit in the control circuit 10.

As described above, the phased array antenna 1 can improve the polarization accuracy and antenna gain when beamforming and transmitting circularly polarized waves. The phased array antenna 1 allows the third circuit 14 to adjust the phase difference and amplitude difference between the first signal and the second signal, thereby adjusting the error in the amount of isolation between the first port 4 and the second port 5 that occurs when beamforming and transmitting a circularly polarized signal, improving the polarization accuracy of the signal radiated from the antenna unit 2 and improving the communication speed. The phased array antenna 1 includes the third circuit 14, which reduces the polarization loss that occurs when beamforming and transmitting a circularly polarized signal, reduces the signal-noise ratio (SNR), and improves the receiving power on the receiving side.

Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are within the scope of the invention and its equivalents as set forth in the claims, as well as the scope and gist of the invention.

For example, the phased array antenna may simultaneously detect detection values using four detectors 15 in the third circuit 14, calculate an average value of the detection values, and adjust the phase and amplitude between the first signal and the second signal.

1 Phased array antenna 2 Antenna section 3 Antenna element 4 First port 5 Second port 5G Fifth generation communication 10 Control circuit 10C Control section 10M Memory section 11 First circuit 12 Second circuit 12B Distribution circuit 12H Second input section 12U Antenna unit 12UF1, 12UF2 Phase adjuster 12Up Antenna circuit 12UP1, 12UP2 Amplifier 12US1, 12US2 Amplitude adjuster 12V First input section 13 Fourth circuit 14 Third circuit 15 Detection section 15A First switch 15B Second switch 15C Power combiner 15D Detection circuit 16 First phase amplitude adjustment section 17 Second phase amplitude adjustment section Hp Second connection section Vp First connection section

Claims (4)

an antenna element having a first port for inputting a first signal and a second port for inputting a second signal having a phase difference of +90° or −90° with respect to the first signal, the first signal and the second signal being combined to generate a circularly polarized wave and transmit the circularly polarized wave;
an antenna section provided with a plurality of the antenna elements;
a control circuit that adjusts a beam direction of the circularly polarized wave radiated from the antenna unit by individually controlling each of the antenna elements, and adjusts a phase difference and an amplitude difference between the first signal and the second signal according to the beam direction.
Phased array antenna. The control circuit includes a first circuit that generates the first signal and the second signal, the phase shift of which is adjusted based on a transmission signal;
a second circuit for adjusting the phase, amplitude, and power of the first signal and the second signal and outputting them individually at each of the antenna elements;
a third circuit that detects a phase and an amplitude between the first signal and the second signal in the second circuit and adjusts the phase difference and the amplitude difference based on the detection result.
2. The phased array antenna of claim 1. the third circuit calculates the phase difference and the amplitude difference between the first signal and the second signal based on detection results of a first power of the first signal, a second power of the second signal, and a third power obtained by combining the first power and the second power, and adjusts the phase difference and the amplitude difference based on the calculation results.
3. The phased array antenna of claim 2. a fourth circuit that applies a first initial adjustment amount to phases and amplitudes of the first signal and the second signal in the first circuit based on a detection result of an initial value of the circularly polarized wave output from the antenna element;
4. The phased array antenna according to claim 2 or 3.

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