Wideband and Reconfigurable Vector Antenna Using Radiation Pattern Diversity for 3-D Direction-of-Arrival Estimation

The direction finding performances of a novel passive, wideband, and radiation pattern (RP) reconfigurable vector antenna (VA) are reported. Accurate estimation of the direction of arrival (DoA) of incoming electromagnetic (EM) fields across the 3-D half-space is obtained over a 1.69:1 impedance bandwidth from the RP reconfigurability of a four-port VA. This antenna consists of only two orthogonal and colocated semicircular arrays of Vivaldi antennas. Due to its reconfigurability, more RPs can be used in addition to those commonly employed in standard VAs to estimate the DoA of incoming EM fields. A new method based on the Cramer-Rao lower bound is proposed in order to select the RP diversity that improves the estimation accuracy across the overall bandwidth. The measured and simulated results are found in good agreement. This paper brings a further step toward developing new concepts of reconfigurable VAs.