Terahertz-Band Direction Finding With Beam-Split and Mutual Coupling Calibration

Terahertz (THz) band is currently envisioned as the key building block for achieving the future sixth generation wireless systems. The ultrawide bandwidth and very narrow beamwidth of THz systems offer the next order of magnitude in user densities and multifunctional behavior. However, wide bandwidth results in a frequency-dependent beampattern causing the beams generated at different subcarriers split and point to different directions. Furthermore, mutual coupling degrades the system's performance. This letter studies the compensation of both beam-split and mutual coupling for direction-of-arrival (DoA) estimation by modeling the beam-split and mutual coupling as an array imperfection. We propose a subspace-based approach using multiple signal classification with CalibRated for bEAm-split and Mutual coupling and MUltiple SIgnal Classification (CREAM-MUSIC) algorithm for this purpose. Via numerical simulations, we show that the proposed CREAM-MUSIC approach accurately estimates the DoAs in the presence of beam-split and mutual coupling.