A DIELECTRICALLY-LOADED ANTENNA

摘要

A dielectrically loaded backfire helical antenna has a cylindrical ceramic core (12) and a feed structure which passes axially through the core to a distal end face of the core where it is connected to helical conductors (10A-10D) located on the outside of the core. Opening out on the proximal end face (12P) of the core is a cavity (21) which is coaxial with the feed structure. A conductive balun layer (20) encircling a portion of the core extends over the proximal end face of the core and the wall (21) of the cavity to connect the helical elements (10A-10D) to the feeder structure where it emerges into the cavity. The presence of the cavity and accommodating some of the length of the balun in the cavity allows a reduction in the size and weight of a dielectrically loaded backfire antenna.