Circularly Polarised Array Antenna

摘要

A circularly polarised array antenna (30) is disclosed. A single layer dielectric substrate (36) has a ground plane (32) located on its upper surface of the substrate and covering only part of the upper surface. A plurality of antenna elements (40-54) are also located on said upper surface of the substrate. Each antenna element has a slot element (60-74) formed in the ground plane and a respective loading element (80-94) located within each slot element. The antenna elements being arranged in a regular array where each respective slot element is sequentially rotated in space with respect to adjacent slot elements, and the loading elements generate a perturbation under excitation. A microstrip feed network (100) is located on the underside of the sub-straw to provide excitation to each slot element, and including feeds of different lengths to be electrically sequentially rotated in common with spatial rotation of the slot elements. A single microstrip feed point (108) extends to the edge of the substrate for connection purposes. A reflecting plane is located parallel to and spaced apart from the underside of the substrate. The ground plane extends to cover the entire microstrip feed array.