Antenna Effects on a Monostatic MIMO Radar for Direction Estimation, a Cramèr-Rao Lower Bound Analysis

Antenna effects on a monostatic multiple-input-multiple-output (MIMO) Radar for direction estimation are studied by analyzing the Cramèr-Rao lower bound (CRLB). The CRLB is derived for a multi-band MIMO Radar system, and is in a form that incorporates the characteristics of a practical antenna array. Two different uniform linear antenna arrays, one narrowband and the another wideband, are investigated by exploring the CRLB. The estimation performance for the real antenna array is compared to that for an ideal array composed of isotropic antenna elements. It is found out that the mutual coupling between antenna elements alters the radiation patterns a lot, and therefore tremendously affects the estimation performance. Furthermore, the study demonstrates that by distributing the transmitted power over several frequency bands, more accurate estimation can be achieved due to frequency diversity, and the negative effects of radiation pattern deviation can be alleviated.