Phased array device

Abstract

This phased array device (1) comprises a plurality of wireless transmitters arranged in an array. Each of the wireless transmitters comprises: a transmission circuit (3) that frequency-converts an IF signal to output an RF signal that has a frequency of 200 GHz to 1 THz; and an antenna element (2) that converts the RF signal to electromagnetic waves and radiates same. The pitch of the antenna element is set so that grating lobes are produced within an area of visibility of the radiation directivity of the phased array device (1). Due to this configuration, the phased array device (1) can be provided, the device allowing the scope of coverage of the antennas to be widened in a frequency band of 200 GHz and above.

Description

Phased Array Device

[0001] The present invention relates to a phased array device having a plurality of radio units arranged in an array.

[0002] In order to overcome the problem of radio wave propagation loss in frequency bands above 200 GHz, it is necessary to increase the equivalent isotopically radiated power (EIRP), which is the sum of the transmitter output power and antenna gain. Non-Patent Document 1 uses a high-gain horn or lens antenna, but because the coverage area of ​​high-gain horns and lens antennas is narrow, an antenna with high EIRP and wide coverage area has not been realized.

[0003] To solve the above problems, a beam steering technique using a phased array device having a plurality of antenna elements arranged in an array has been proposed. For example, Non-Patent Document 2 proposes a technique for widening the coverage area in a system using a frequency band of 200 GHz or less by using a phased array beam steering technique.

[0004] H. Hamada et al., "300-GHz-Band 120-Gb / s Wireless Front-End Based on InP-HEMT PAs and Mixers," in IEEE Journal of Solid-State Circuits, vol. 55, no. 9, pp. 2316-2335, Sept. 2020.W. Zhu et al., "A Packaged 90-to-96GHz 16-Element Phased Array with 18.8 / 15.8dBm Psat / OP1dB, 14.8% TX PAE in 65nm CMOS Process and +51dBm Array EIRP," 2022 IEEE Symposium on VLSI Technology and Circuits (VLSI Technology and Circuits), 2022, pp. 128-129.

[0005] In order to widen the coverage range of a phased array, the pitch of the antenna elements needs to be half the free space wavelength, but in frequency bands above 200 GHz, the pitch of the antenna elements needs to be much larger than half the wavelength due to factors such as the large chip width of the antenna elements.The steering range of the main beam of the phased array becomes narrower as the pitch of the antenna elements increases, which poses a problem of narrowing the coverage range of the phased array.

[0006] An object of the present invention is to solve the above-mentioned problems and to provide a phased array device that can widen the antenna coverage range in frequency bands of 200 GHz or higher.

[0007] In order to solve the above problems, the phased array device of the present invention is a phased array device including a plurality of radio transmitters arranged in an array, wherein the radio transmitters include a transmission circuit that frequency-converts an IF signal and outputs an RF signal having a frequency of 200 GHz to 1 THz, and an antenna element that converts the RF signal into an electromagnetic wave and radiates it, and the pitch of the antenna elements is set so that grating lobes occur within a visible range of the radiation directivity of the phased array device.

[0008] In order to solve the above problems, the phased array device of the present invention is a phased array device including a plurality of wireless receivers arranged in an array, wherein the wireless receivers include antenna elements that convert electromagnetic waves having a frequency of 200 GHz to 1 THz into RF signals, and a receiving circuit that frequency converts the RF signals and outputs IF signals, and the pitch of the antenna elements is set so that grating lobes occur within a visible range of the radiation directivity of the phased array device.

[0009] According to the present invention, it is possible to provide a phased array device that can widen the coverage area of ​​the antenna in the frequency band of 200 GHz or higher.

[0010] FIG. 1 is a diagram showing an example of the configuration of a two-dimensional phased array device according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of the configuration of a one-dimensional phased array device according to an embodiment of the present invention. FIG. 3 is a diagram showing an example of an array factor of a phased array device according to an embodiment of the present invention. FIG. 4 is a diagram showing an example of the configuration of a transmission circuit of a phased array device according to an embodiment of the present invention. FIG. 5 is a diagram showing an example of the configuration of a reception circuit of a phased array device according to an embodiment of the present invention. FIG. 6 is a diagram showing an example of the array factor of a phased array device according to an embodiment of the present invention.

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes embodiments of the present invention with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0012] Fig. 1 is a diagram showing an example of the configuration of a two-dimensional phased array device according to an embodiment of the present invention. The example of the configuration of the phased array device 1 shown in Fig. 1 is an example of the configuration of a two-dimensional phased array device 1 in which multiple wireless transmitters or wireless receivers are arranged in an array. The wireless transmitter includes a transmitting circuit 3 and an antenna element, and the wireless receiver includes a receiving circuit 3 and an antenna element. The phased array device 1 is an antenna that obtains a desired radiation directivity (radiation pattern) by controlling the power and phase of the multiple wireless transmitters or multiple wireless receivers arranged in an array.

[0013] The wireless transmitter includes a transmission circuit 3 that converts the frequency of an intermediate frequency (IF) signal and outputs an RF (Radio Frequency) signal having a frequency of 200 GHz to 1 THz, and an antenna element 2 that converts the RF signal into an electromagnetic wave and radiates it. The wireless receiver includes the antenna element 2 that converts the electromagnetic wave having a frequency of 200 GHz to 1 THz into an RF signal, and a reception circuit 3 that converts the RF signal into a IF signal.

[0014] In frequency bands where the frequency of the RF signal is 200 GHz or higher, the pitch (d) of the antenna elements 2 needs to be significantly larger than half the wavelength (λ / 2) of the free space wavelength (λ) due to factors such as the large chip width (w) of the antenna elements 2. Since the steering range of the main beam of the phased array narrows as the pitch (d) of the antenna elements 2 increases, the coverage range of the phased array antenna cannot be widened by the main lobe alone.

[0015] In the embodiment of the present invention, the pitch (d) of the antenna elements 2 is set to a value greater than the free space wavelength (λ), thereby utilizing grating lobes that occur in the visible range to expand the overall coverage range of the phased array.

[0016] Because electromagnetic wave propagation loss is large in the frequency band above 200 GHz, the effect of multipath propagation tends to be relatively small when using grating lobes. In this embodiment, the range that cannot be covered by the main lobe is covered by the grating lobe, thereby expanding the overall coverage range of the phased array.

[0017] Fig. 2 is a diagram showing an example of the configuration of a one-dimensional phased array apparatus according to an embodiment of the present invention. The phased array apparatus 1 in Fig. 2 is a one-dimensional phased array apparatus in which four wireless transmitters are arranged at equal intervals. Each wireless transmitter includes a transmission circuit 3 that converts the frequency of an IF signal and outputs an RF signal having a frequency between 200 GHz and 1 THz, and an antenna element 2 that converts the RF signal into an electromagnetic wave and radiates it.

[0018] The transmitter circuit 3 includes a frequency converter circuit and an RF signal amplifier circuit, and the frequency converter circuit can be integrated, for example, on a Si substrate using a CMOS (Complementary Metal Oxide Semiconductor) structure, and the RF signal amplifier circuit can be integrated, for example, on an InP substrate. The antenna element can be, for example, a Vivaldi antenna, but is not limited to this.

[0019] In the configuration example of FIG. 2, the antenna pitch (d) of the antenna element 2 is 3.85 mm, and is set to be approximately 3.3λ with respect to the free space wavelength (λ=1.16 mm) when the frequency of the RF signal is 258 GHz.

[0020] FIG. 2 illustrates an example configuration in which the present invention is applied to a phased array device in which four wireless transmitters are arranged one-dimensionally at a specific wireless frequency; however, it is clear that the present invention can be applied to a frequency band of 200 GHz to 1 THz, and can also be applied to a phased array device in which antenna elements 2 are arranged two-dimensionally.

[0021] When the pitch (d) of the antenna elements 2 is set to satisfy M·λ≦d<(M+1)·λ, N=2·M grating lobes are generated within the visible range of θ: −90° to +90°. In the configuration example of Figure 2, the antenna pitch (d) = 3.3λ, so a total of N=6 grating lobes are generated on both sides of the main lobe. Figure 3 shows the results of calculating the array factor of the phased array device 1 in the configuration example of Figure 2.

[0022] As shown in the array factor calculation results in Figure 3, the steering range of the main lobe is approximately 18°. Meanwhile, the steering range of the grating lobes that occur on both sides of the main lobe is also approximately 18°. Because the steering range of the main lobe and the steering range of the grating lobes that occur on both sides of the main lobe are seamlessly connected, the range that cannot be covered by the main lobe can be covered by the grating lobes, thereby widening the overall coverage range of the phased array.

[0023] Here, if the number of grating lobes is increased to 2M, the steering resolution becomes 1 / M of the conventional resolution. As a result, the phase shift step required in the phase shifter for changing the excitation phase of the phased array device 1 is relaxed by M times.

[0024] The desired EIRP is ｒｅｑ In this case, the number of antenna elements (n) is ｒｅｑ / (P1 ｅｌｅｍｅｎｔ ・G1ｅｌｅｍｅｎｔ ), the desired EIRP can be achieved with the minimum number of antenna elements. １ｅｌｅｍｅｎｔ is the output power of one element, G1 ｅｌｅｍｅｎｔ is the antenna gain of one element. Also, the desired EIRP ｒｅｑ By minimizing the number of antenna elements (n) to obtain , it is possible to minimize the number of dividers required to feed each antenna element.

[0025] When actually using a phased array, it is necessary to use it in the far field. To set the far field distance to α or less, the antenna pitch (d) and the number of antenna elements (n) should be set to satisfy the following formula (1): d< (1 / n) (αλ / 2) １／２ ...(1)

[0026] 4 is a diagram showing an example of the configuration of a transmission circuit 3 of a wireless transmitter in a phased array device according to an embodiment of the present invention. FIG. 5 is a diagram showing an example of the configuration of a reception circuit of a wireless receiver in a phased array device according to an embodiment of the present invention.

[0027] The transmission circuit 3 includes an IF amplifier circuit 31 that amplifies a low-frequency (2 to 27 GHz) IF signal, a mixer circuit 32 that converts the IF signal into a high-frequency (200 GHz to 1 THz) RF signal using an LO signal from a local oscillator (LO), an RF amplifier circuit 33 that amplifies the RF signal, a phase shifter 34 that controls the phase of the LO signal to change the excitation phase, a frequency multiplier circuit 35 that multiplies the frequency of the output signal of the phase shifter 34, a buffer circuit 36 ​​that buffers the frequency-multiplied signal, and a phased array control circuit 37. When the multiplication factor of the frequency multiplier circuit 35 is K, the coverage range of the phase shifter 34 is 360° / K.

[0028] The receiving circuit 3 includes an RF amplifier circuit 33 that amplifies a high-frequency (200 GHz to 1 THz) RF signal, a mixer circuit 32 that converts the RF signal into a low-frequency (2 to 27 GHz) IF signal using an LO signal from a local oscillator (LO), an IF amplifier circuit 31 that amplifies the IF signal, a phase shifter 34 that controls the phase of the LO signal to change the excitation phase, a frequency multiplier circuit 35 that multiplies the frequency of the output signal of the phase shifter 34, a buffer circuit 36 ​​that buffers the frequency-multiplied signal, and a phased array control circuit 37. When the multiplication factor of the frequency multiplier circuit 35 is K, the coverage range of the phase shifter 34 is 360° / K.

[0029] To reduce the effects of multipath due to the use of grating lobes that occur within the visible range, the power of a portion of the grating lobe may be suppressed. To reduce the effects of multipath due to grating lobes, the power reduction compared to the power of the main lobe may be set to a predetermined value, for example, 3 dB. In this embodiment, the antenna characteristics (element factor) of the antenna elements are used to suppress the power of unnecessary grating lobes.

[0030] 6 is a diagram showing an example of an array factor of a phased array apparatus according to an embodiment of the present invention, in which N=6 grating lobes are generated on both sides of the main lobe.

[0031] As shown in Figure 6, the antenna characteristics (element factor) of the antenna elements are used to suppress the power of the two outermost grating lobes out of the six grating lobes. Using the antenna characteristics (element factor) of the antenna elements makes it possible to suppress the power of unnecessary grating lobes. This makes it possible to control the number of grating lobes that cause multipath, and also improve the array gain.

[0032] 1...phased array device, 2...antenna element, 3...transmitting circuit, receiving circuit

Claims

1. A phased array device comprising a plurality of wireless transmitters arranged in an array, wherein the wireless transmitters comprise a transmission circuit which converts the frequency of an IF signal and outputs an RF signal having a frequency between 200 GHz and 1 THz, and an antenna element which converts the RF signal into an electromagnetic wave and radiates it, and the pitch of the antenna elements is set so that a grating lobe is generated within the visible range of the radiation directivity of the phased array device.

2. A phased array device comprising a plurality of wireless receivers arranged in an array, wherein the wireless receivers comprise antenna elements which convert electromagnetic waves having a frequency between 200 GHz and 1 THz into RF signals, and a receiving circuit which performs frequency conversion on the RF signals and outputs IF signals, and the pitch of the antenna elements is set so that grating lobes are generated within the visible range of the radiation directivity of the phased array device.

3. The phased array apparatus according to claim 1, wherein the transmission circuit comprises a phase shifter which controls the phase of an LO signal, and a frequency multiplier which multiplies the frequency of an output signal of the phase shifter, and a mixer circuit which converts the IF signal into the RF signal by using the frequency-multiplied LO signal.

4. The phased array device according to claim 2, wherein the receiving circuit comprises a phase shifter which controls the phase of an LO signal, and a frequency multiplier which multiplies the frequency of an output signal of the phase shifter, and further comprises a mixer circuit which converts the RF signal into the IF signal by using the frequency-multiplied LO signal.

5. The pitch and number of the antenna elements are set to satisfy the following formula (1): d < (1 / n) (α λ / 2) １／２ d: pitch of antenna elements, n: number of antenna elements, α: far-field distance, λ: free space wavelength. The phased array device according to claim 1 .

6. A phased array device as claimed in any one of claims 1 to 4, wherein the antenna characteristics of the antenna elements are set so that a power drop in a part of the grating lobe compared to the power of the main lobe of the radiation directivity is a predetermined value.

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