Publication: Publication Date: 2019/02/01 Vol. E102-BNo. 2pp. 166-173 Type of Manuscript: INVITED PAPER (Special Section on Recent Progress in Antennas and Propagation in Conjunction with Main Topics of ISAP2017) Category: Antennas Keyword: ultra-wideband, 5G, beamformer, arrays, frequency independent, self-mixing,