Radiation-pattern reconfigurable and wideband vector antenna for 3-D direction finding

The direction-finding performance of a radiation-pattern reconfigurable and wideband vector antenna is reported. This eight-port vector antenna consisted of the arrangement of circular arrays of Vivaldi antennas. Accurate estimation of the direction of arrival of an incoming vertically- or horizontally-polarized electromagnetic field across the three-dimensional upper half-space was achieved over a frequency bandwidth of 8.2:1 thanks to radiation-pattern reconfigurability. The proposed vector antenna offered the opportunity of using more radiation patterns than those commonly used in standard vector antennas for estimating the direction of arrival of incoming electromagnetic fields, which led to better estimation accuracy. Measurement results were found to be in good agreement with the simulated results obtained from full-wave electromagnetic simulations.