Multimode based direction finding

Direction finding by exploiting higher order modes of a modified biconical antenna is considered. The direction of arrival (DOA) of an incident wave is estimated by using the fact that the different modes have different directional properties. Since only one antenna element is used, the spatial requirements of an array of elements is avoided as well as problems with mutual coupling between antenna elements. The direction finding performance is examined by calculating the Cramer-Rao lower bound (CRB) and the maximum likelihood (ML) estimator for several different cases. It is found that the multimode antenna offers direction finding performance comparable to the traditional antenna array using only a single antenna element.