Air-Filled SIW Remote Antenna Unit With True Time Delay Optical Beamforming for mmWave-Over-Fiber Systems

• DOI: 10.1109/jlt.2022.3187555
• Publication Date: 2022-06-30T19:38:53Z
• Authors: Igor Lima de Paula; Laurens Bogaert; Olivier Caytan; Joris Van Kerrebr...; Arno Moerman; Muhammad Muneeb; Quinten Van den B...; Guy Torfs; Johan Bauwelinck; Hendrik Rogier; Piet Demeester; Gunther Roelkens; Sam Lemey
• Keywords: True time delay; Beam steering; Waveguide

A low-complexity and efficient mmWave-over-fiber remote antenna unit (RAU) is proposed that enables broadband transmission wide-angle squint-free beam steering in the full [26.5-29.5]GHz n257 5G band.It leverages an in-house developed optical beamforming network (OBFN), implemented on a silicon photonics integrated circuit, optically enabled 1x4 uniform linear array (ULA), enabling grating-lobe-free between [-50 • , 50 ].The elements (AEs) of ULA are air-filled substrate-integratedwaveguide technology.They adopt novel improved aperturecoupled feeding scheme to achieve high efficiency, isolation minimal back radiation over broad frequency band.Each AE compactly co-optimized with dedicated opto-electrical transmit chain, maximizing RAU's performance, including flexibility energy while minimizing its size.The separately packaged OBFN implements true-time-delay by means four switchable delay lines capable discretely tuning difference AEs resolution 1.6 ps, up maximum 49.6 ps fully exploit ULA's scan range.Measurements show excellently matched [25.1-30.75]GHz band, exhibit (>15 dB) operating feature stable peak gain 6.8±0.72 dBi beamwidth at least 95 .Additionally, was successfully demonstrated towards angles 51.8 degradation below 0.6 dB.Finally, 1×4 establishes 64-QAM wireless communication link 2.2 Gbaud (13.2 Gbps) error vector magnitude 7.6%.