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Real-Time mmWave Channel Sounding through Full Digital Beamforming with 3D Dual-Polarized Phased-Array Antennas



Derek Caudill, Jack Chuang, Sung Yun Jun, Camillo Gentile, Nada T. Golmie


We describe a 29.5 GHz channel sounder that individually digitizes, through time multiplexing, all antennas of multiple dual-polarized 8 x 8 phased arrays at the transmitter and receiver, and performs digital beamforming in post-processing to synthesize a steerable beam. To our knowledge, we are first to implement full digital beamforming with phased arrays, realized through highly stable Rubidium clocks and local oscillators coupled with precision over-the-air calibration techniques developed in house. By bypassing the time-consuming programming of steering weights that is inherent to analog beamforming, we can achieve a 3D double-omnidirectional dual-polarized channel sweep in just 1.3 ms, for real-time channel sounding. By in turn bypassing the coarse precision of analog weights, we can obtain quasi-ideal beam patterns through the effectively unlimited precision of digital weights, enabling fine weight tapering for sidelobe suppression and fine weight calibration for the hardware non-idealities of the system. This translates into 0.5° average estimation in 3D double-directional angle, as demonstrated by measurement results. The system was also demonstrated to operate up to a range of at least 150 m.
IEEE Transactions on Microwave Theory and Techniques


5G, propagation, mmWave, 29.5 GHz, channel sounder, calibration


Caudill, D. , Chuang, J. , Jun, S. , Gentile, C. and Golmie, N. (2021), Real-Time mmWave Channel Sounding through Full Digital Beamforming with 3D Dual-Polarized Phased-Array Antennas, IEEE Transactions on Microwave Theory and Techniques, [online],, (Accessed June 25, 2022)
Created September 7, 2021, Updated January 4, 2022