[3] [3] ABHAYAPALA T D,WARD D B.Wideband beamspace processing using orthogonal modal beamformers［J］.Journal of Signal Processing Systems,2011,63(3):277-286.

[7] [7] ZHANG F C,FAN W,GERT F P.Frequency-invariant uniform circular array for wideband mm-wave channel characterization［J］.IEEE Antennas and Wireless Propagation Letters,2016,16:641-644.

[8] [8] LIAO B,TSUI K M,CHAN S C.Frequency invariant uniform concentric circular arrays with directional elements［J］.IEEE Transactions on Aerospace and Electronic Systems,2013,49(2):871-884.

[9] [9] HUANG G P,CHEN J D,JACOB B.Insights into frequency-invariant beamforming with concentric circular microphone arrays［J］.IEEE/ACM Transactions on Audio,Speech,and Language Processing,2018,26(12):2305-2318.

[11] [11] SAXENA P,KOTHARI A G.Performance analysis of adaptive beamforming algorithms for smart antennas［J］.IERI Procedia,2014,10:131-137.