Patent ID: 8704728
Filing Date: 2014-04-22
Classification: G01C,G01S,H01Q

Abstract:
1. A single-aperture direction-finding antenna comprising: a. at least one conductive driven element located above a conductive ground surface; b. a plurality of feed ports driving said at least one conductive driven element, wherein the feed ports and the driven element are rotationally-symmetric about a common center above said conductive ground surface and support at least two direction-finding antenna modes while sharing a single radiating aperture; and c. at least one rotationally-symmetric conductive member electrically connected to said conductive ground surface at a predetermined distance from said common center and extending away from the ground surface toward said at least one conductive driven element while leaving a gap between said at least one conductive driven element and said conductive member, wherein the height of said conductive member and said gap are selected to maximize the efficiency and improve the rotational symmetry of the at least two direction-finding antenna modes, whereby azimuthal phase and magnitude variations of said antenna modes are reduced resulting in improved angle-of-arrival accuracy and direction-finding performance over a hemisphere above said conductive ground surface.