Broadband modified-circle-shape patch antenna with H-aperture feeding for a passive radar array

Abstract In this paper, the design of a broadband modified-circle-shape patch antenna with H-aperture feeding is presented, to be used as single radiating element in the array of the surveillance channel of an UHF passive radar. Different techniques are proposed to achieve a relative bandwidth of more than 30%, and challenging radiation pattern characteristics for the defined application. The achievement of these requirements is proved through measurements in anechoic chamber. A NULA is designed using optimization techniques and considering coupling effects between elements. The NULA was integrated in IDEPAR, the passive radar demonstrator developed in the University of Alcala, and validated through measurement campaigns. Results prove a significant improvement of the passive radar target detection and bearing estimation capabilities.