Beam steering of lens antenna with 4x4 element 4-port antenna in the 300-GHz band

Oct 22, 2026

A circularly polarized 4x4 element 4-port antenna for the 300 GHz band is designed and fabricated, targeting IEEE 802.15.3d channels 16 and 17. Measured gain exceeds 10 dBic with axial ratio below 3 dB from 285.12 GHz to 289.44 GHz. A lens with 100 mm focal length and 35 mm radius is developed; lens-assisted gain reaches 40 dBic in calculation. Experimental results confirm that placing the antenna near the focal region enables measured beam steering, while ideal focal placement without phase control limits steering.

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CategoryTechnology

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Introduction

Design and fabrication of 4x4 elements antenna with 4-ports

IEICE Communications Express, Vol.14, No.3, 91–94 LETTER Beam steering of lens antenna with 4x4 element 4-port antenna in the 300-GHz band Seiji Nishi 1, a), Kazuhiko Tamesue1 , Kunihisa Jitsuno2 , Toshio Sato 1 , Takuro Sato 1 , and Tetsuya Kawanishi 1, 2 Abstract A circular polarized 4x4 element 4-port antenna in the 300 GHz band was designed and fabricated. Antenna gain of more than 10 dBic and axial ratio of less than 3 dB were obtained at 285.12 GHz to 289.44 GHz, which are ch 16 and ch 17 of IEEE 802.15.3d. If the power of the four ports were ideally combined, the antenna gain would increase by 6 dB to 16 dBic. A lens was designed for the circularly polarized 4x4 element 4-port antenna. The focal length of the lens was 100 mm and lens radius is 35 mm. An antenna gain of 40 dBic was calculated using the lens. Placing the 4x4 element 4-port antenna at the focal length ofthe lens would provide maximum gain, but no beam steering by phase controle. Placing the antenna closer than the focal length would lower the antenna gain but allow beam steering by phase controle. The antenna gain and beam tilt angle were calculated for diﬀerent distances between the lens and the 4x4 element 4-port antenna. A lens antenna with a lens height of 70 mm was assembled and beam steering was measured. Keywords: 300-GHz band, patch antenna, circular polarization, lens, beam steering Classiﬁcation: Antennas and propagation 1. Introduction In recent years, the 300 GHz band has attracted much attention for communications exceeding 100 Gbps [1, 2], and has been standardized in IEEE 802 .15.3d [3] . In communications over a distance in the 300 GHz band, a larger antenna gain is required, and lens antennas are being considered [4, 5, 6] . We are conducting transmission experiments using IEEE 802.15.3d channels 16 and 17 [7] . We are developing a circularly polarized antenna tobe used here using adielectric substrate [6, 8] . In this paper, we designed and fabricated a 4x4 4-port antenna for use with Ch 16 and Ch 17 of IEEE 802 .15.3d. In Chapter 2, we describe the design of the 4x4 4-port antenna and the prototype results. Chapter 3 describes the beam steering of the 4x4 element 4-port antenna, and Chapter 4 describes the lens design of the 4x4 element 4-port antenna. Chapter 5 describes the beam steering when the antenna is placed closer than the focal length of the lens. 1 Waseda Research Institute for Science and Engineering, Waseda University, Shinjuku-ku, Tokyo 169-8555, Japan 2 Faculty of Science and Engineering, Waseda University, Shinjuku-ku, Tokyo 169-8555, Japan a) [s.nishi3@kurenai.waseda.jp](s.nishi3@kurenai.waseda.jp) DOI: 10.23919/comex.2024XBL0167 Received September 26, 2024 Accepted December 6, 2024 Publicized January 28, 2025 Copyedited March 1, 2025 2. Design and fabrication of 4x4 elements antenna with 4-ports The 4x4 element antenna was fabricated with a 4-layer dielectric substrate. The structure of the dielectric substrate is shown in Fig. 1. 1-layer metal is used for the patch antenna, and 2-, 3-, and 4-layer metal form the strip line. The strip line and the patch antenna are connected via slots in the 2-layer metal. The interface is converted from 4-layer metal to WR 3.4 waveguide. The dielectric is a low-loss Namics Adfrema bonding ﬁlm [6] . A photograph of the substrate and pattern diagram of the 4x4 element 4-port antenna are shown in Fig. 2. The element spacing is 0.85 􀀕, where 􀀕 Fig. 1 Layer structure. Tan􀀎 is estimated in Ref. [6] . Fig. 2 Photo of dielectric substrate and pattern diagram of 4x4 element 4-port antenna. This work is licensed under a Creative Commons Attribution Non Commercial, No Derivatives 4 .0 License. Copyright © 2025 The Institute of Electronics, Information and Communication Engineers 91 IEICE Communications Express, Vol.14, No.3, 91–94 Fig. 3 Photograph of assembled antenna. (a) Front. (b) Back. Fig. 4 Measured antenna gain of 4x4 element 4-port

FAQs

What performance was achieved for the 4x4 element 4-port antenna in the 300 GHz band?

The antenna achieved gain above 10 dBic and axial ratio less than 3 dB between 285.12 GHz and 289.44 GHz.

How does the lens influence antenna gain?

A lens was designed with 100 mm focal length; calculated gain with the lens reaches about 40 dBic.

Why does beam steering depend on the antenna position relative to the lens focal length?

At the focal length, maximum gain is obtained but beam steering by phase control is not achieved, while positioning closer reduces gain but enables beam steering via phase control.

Oct 22, 2026

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