A Circularly Polarized Short Backfire Antenna Excited by an Unbalance-Fed Cross Aperture

Abstract—An unbalance-fed cross aperture is developed to excite a short backfire antenna (SBA) for circular polarization. The cross aperture consists of two orthogonal H-shaped slots with a pair of capacitive stubs and is fed by a single probe that forms an unbalanced feed with a shorting pin. It is demonstrated that the cross-aperture-excited SBA can achieve an axial ratio ( Q dB) bandwidth of 4.2 % with a voltage standing wave ratio (VSWR) bandwidth of 6.5 % @†ƒ‡ ‚ I PA and a gain of 14 dBi. The antenna structure is described and the simulation and experimental results are presented. The mechanisms for impedance matching and circular-polarization production are analyzed. Index Terms—Circularly polarized antenna, short backfire antenna (SBA), slot-fed antenna. I