EP-4738607-A1 - ARRAY ANTENNA DEVICE

Abstract

An array antenna device (100) is provided with: a first layer (10) in which a plurality of antenna elements (11) are arranged in a grid shape; and a second layer (20) that overlaps the first layer (10). The second layer (20) has: an IF signal main line (21) and an LO signal main line (22) that extend in the orthogonal direction to each other; an IF signal branch line (23) and an LO signal branch line (24) that extend in the orthogonal direction of the IF signal main line (21) and the LO signal main line (22); and a plurality of mixers (29) that are arranged in the same grid shape as the plurality of antenna elements (11) at the intersections of the branch lines (23, 24), and electrically connected to the branch lines (23, 24) and the antenna elements (11). Phase shifters (25, 26, 27, 28) are provided between the connection points of the branch lines (23, 24) in the main lines (21, 22) and/or between the connection points of the mixers (29) in the branch lines (23, 24). The first layer (10) and the second layer (20) vertically overlap such that the arrangement region (110) of the plurality of antenna elements (11) in the first layer (10) and the arrangement region (290) of the plurality of mixers (29) in the second layer (20) overlap in a plan view.

Inventors

• FUJISHIMA MINORU

Assignees

• Hiroshima University

Dates

Publication Date

20260506

Application Date

20240730

Claims (9)

1. An array antenna device, comprising: a first layer in which a plurality of antenna elements are arranged in a grid pattern; and a second layer stacked on the first layer, wherein the second layer includes an IF signal main line and an LO signal main line extending in mutually orthogonal directions, a plurality of IF signal branch lines and a plurality of LO signal branch lines extending in directions orthogonal to the IF signal main line and the LO signal main line, respectively, a plurality of mixers arranged in a same grid pattern as the plurality of antenna elements at each intersection of the plurality of IF signal branch lines and the plurality of LO signal branch lines, and electrically connected to the plurality of IF signal branch lines, the plurality of LO signal branch lines, and the plurality of antenna elements, respectively, a plurality of first phase shifters in at least one of between each connection point of the plurality of IF signal branch lines in the IF signal main line and between each connection point of the plurality of mixers in the plurality of LO signal branch lines, and a plurality of second phase shifters in at least one of between each connection point of the plurality of LO signal branch lines in the LO signal main line and between each connection point of the plurality of mixers in the plurality of IF signal branch lines, and the first layer and the second layer are stacked vertically such that an arrangement region of the plurality of antenna elements in the first layer and an arrangement region of the plurality of mixers in the second layer overlap in plan view.
2. The array antenna device according to claim 1, wherein the plurality of first phase shifter are inserted between each connection point of the plurality of IF signal branch lines in the IF signal main line, and the second layer includes a plurality of third phase shifters or meander wiring between each connection point of the plurality of mixers in the plurality of LO signal branch lines.
3. The array antenna device according to claim 1, wherein the plurality of second phase shifters are inserted between each connection point of the plurality of LO signal branch lines in the LO signal main line, and the second layer includes a plurality of third phase shifters or meander wiring between each connection point of the plurality of mixers in the plurality of IF signal branch lines.
4. The array antenna device according to claim 1, wherein the plurality of first phase shifters are inserted between each connection point of the plurality of IF signal branch lines in the IF signal main line, the plurality of second phase shifters are inserted between each connection point of the plurality of LO signal branch lines in the LO signal main line, and the second layer includes a plurality of third phase shifters or meander wiring between each connection point of the plurality of mixers in the plurality of IF signal branch lines and a plurality of fourth phase shifters or meander wiring between each connection point of the plurality of mixers in the plurality of LO signal branch lines.
5. The array antenna device according to claim 4, wherein the IF signal main line and the plurality of first phase shifters are implemented on a first chip, the LO signal main line and the plurality of second phase shifters are implemented on a second chip, the plurality of mixers, the plurality of IF signal branch lines, the plurality of LO signal branch lines, the plurality of third phase shifter or meander wiring as a substitute therefor, and the plurality of fourth phase shifters or meander wiring as a substitute therefor are implemented on a third chip, and the first chip and the second chip are connected to the third chip to form the second layer.
6. The array antenna device according to claim 5, wherein a plurality of the first chips are connected in series so as to extend the IF signal main line, a plurality of the second chips are connected in series so as to extend the LO signal main line, a plurality of the third chips are connected horizontally and vertically so as to extend the plurality of IF signal branch lines and the plurality of LO signal branch lines, respectively, and the plurality of the first chips connected in series and the plurality of the second chips connected in series are connected to the plurality of the third chips connected horizontally and vertically to form the second layer.
7. The array antenna device according to any one of claims 1 to 6, wherein at least one of the plurality of IF signal branch lines and the plurality of LO signal branch lines are arranged in parallel at a same pitch as the plurality of antenna elements.
8. The array antenna device according to any one of claims 1 to 6, wherein the first layer is a printed circuit board, and the second layer is a semiconductor substrate.
9. The array antenna device according to claims 7, wherein the first layer is a printed circuit board, and the second layer is a semiconductor substrate.

Description

TECHNICAL FIELD The present invention relates to a wireless device equipped with an array antenna, and more particularly, to an array antenna device suitable for use in a transceiver operating in the 300 GHz band. BACKGROUND ART FIG. 7 is a graph illustrating the relationship between frequency bandwidth and S/N ratio for each received power level of radio waves. The horizontal axis of the graph represents the frequency bandwidth, and the vertical axis represents the S/N ratio. The graph plots the relationship between frequency bandwidth and S/N ratio when the received power Pr is 0.1 µW (equivalent to -40 dBm), 1 µW (equivalent to -30 dBm), and 10 µW (equivalent to -20 dBm). As shown in the graph, the S/N ratio decreases as the frequency bandwidth increases, regardless of the magnitude of Pr. The graph includes auxiliary lines indicating the required S/N ratios for each modulation scheme-QPSK (Quadrature Phase Shift Keying), 16QAM (16 Quadrature Amplitude Modulation), and 64QAM (64 Quadrature Amplitude Modulation)-to achieve a BER (Bit Error Rate) of less than 10-3. According to this, at a frequency bandwidth of 25 GHz, communication is possible with any of the modulation schemes (QPSK, 16QAM, or 64QAM) if Pr is 0.1 µW or higher. However, at a frequency bandwidth of 50 GHz, the S/N ratio becomes too low for Pr of 0.1 µW, making communication with QPSK difficult. Furthermore, to achieve stable QPSK communication at even higher frequency bandwidths of around 100 GHz, a received power of 1 µW or higher is required. The sixth-generation mobile communication system (6G) aims to achieve data rates of 100 Gbps or higher using even higher frequency bands of 300 GHz compared to the fifth-generation mobile communication system (5G). Therefore, in next-generation mobile communication systems, which will increasingly utilize higher frequencies and higher data rates, it will be necessary to increase the output power of transmitters to maintain large received power. Up until now, approaches to increase the output power of transceivers operating in the 300 GHz band have included using lenses or horns to enhance antenna gain, or employing rat-race power couplers to power-couple a plurality of RF signals and thereby increase the output power of a single transceiver (see, for example, Patent Literature 1). CITATION LIST PATENT LITERATURE Patent Literature 1: WO 2020/110814 A1 SUMMARY OF THE INVENTION TECHNICAL PROBLEM From the perspective of Equivalent Isotropic Radiation Power (EIRP), the received power can be evaluated as follows: given the distance d between the transmitter and the receiver, and the antenna area Ar of the receiver, the received power Pr can be expressed as Pr = EIPR·Ar/4πd2. In other words, the received power is determined by the antenna area Ar of the receiver, irrespective of the frequency bandwidth. The larger the antenna area, the greater the antenna gain, and thus, the greater the received power. To increase antenna gain, it is effective to adopt an array antenna in which a plurality of antenna elements is arranged. Furthermore, by adopting a phased array antenna, beamforming technology and beam sweeping become available. Beamforming allows for transmitting radio waves in a specific direction or receiving radio waves from a specific direction by adjusting the signal phase of each antenna element, while beam sweeping enables freely changing the beam direction. This approach not only broadens the beam control angle compared to using lenses or horns but also makes beamforming itself easier. In an array antenna, the antenna elements are arranged at a pitch of half the wavelength of the radio waves. When it comes to the 300 GHz band, it is necessary to arrange the antenna elements at a pitch of approximately 500 µm. Therefore, if one attempts to adopt an array antenna with antenna elements arranged in a two-dimensional grid for a transceiver using the 300 GHz band, the transceiver circuit must be placed in an area of about 500 µm square. Although the miniaturization of semiconductor processes can reduce the size of transistors, passive elements such as inductance elements and capacitance elements are difficult to miniaturize. Consequently, it is challenging to place circuits disclosed in Patent Literature 1 in such a narrow area. Thus, adopting an array antenna for a transceiver using the 300 GHz band is difficult due to the constraints of circuit placement area. In view of the above problem, it is an object of the present invention to provide an array antenna device capable of utilizing the 300 GHz band. SOLUTION TO THE PROBLEM An array antenna device according to one aspect of the present invention includes a first layer in which a plurality of antenna elements is arranged in a grid pattern and a second layer stacked on the first layer. The second layer includes an IF signal main line and an LO signal main line extending in mutually orthogonal directions, a plurality of IF signal branch lines and a plur