Cramer-Rao Lower Bound for DoA Estimation with RF Lens-Embedded Antenna Array

In this paper, we consider the Cramér-Rao lower bound (CRLB) for estimation of a lens-embedded antenna array with deterministic parameters. Unlike CRLB of uniform linear array (ULA), it is noted that CRLB for direction of arrival (DoA) of lens-embedded antenna array is dominated by not only angle but characteristics of lens. Derivation is based on the approximation that amplitude of received signal with lens is approximated to Gaussian function. We confirmed that parameters needed to design a lens can be derived by standard deviation of Gaussian, which represents characteristic of received signal, by simulation of beam propagation method. Well-designed lens antenna shows better performance than ULA in terms of estimating DoA. This is a useful derivation because, result can be the guideline for designing parameters of lens to satisfy certain purpose.