Multi-band Active Arrays for Gridless DoA and Spectral Response Sensing

This paper develops model and method tailored for multi-band active arrays where the targets’ gridless direction-of-arrival (DoA) and spectral responses are sensed jointly. In the literature, most works in DoA estimation assume narrow-band probing signals. With modern 5G/6G and sensing systems operating on multi-bands, models and methods tailored for multi-band active sensing are necessary. Following our recent work, we use the greatest common divisor of multiple frequencies for joint signal processing and DoA estimation. One key new element is the physically sensible assumption that targets’ frequency responses can be different at different frequencies. The corresponding signal model, optimisation formulation, and optimisation solver are developed. Numerical simulations are conducted. With the assumption that the targets’ spectral responses have limited degree of freedom, we show that the gridless DoA and spectral response can be estimated jointly, and the number of targets can be more than the antenna elements even for uniform linear arrays (ULA).