Beam Steering of Lens Antenna with 4x4 Element 4-Port Antenna in the 300-GHz Band

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 of the 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.