A low-profile sinuous antenna

A lens loaded ferrite backed sinuous antenna is demonstrated where the metallic cavity side wall is eliminated to increase its operational bandwidth. The sinuous aperture forms the fundamental radiator and is loaded with an electrically small lens in order to redirect the power towards the upper hemisphere. The antenna is backed by a ferrite ground plane and is center-fed with 75 Ω cable bundle to obtain good match. The presented configuration has active VSWR <; 3, circular polarized gain > 0 dBiC and wobble of wave (WoW) <; 2dB in the frequency range of 500 MHz to 2.5 GHz while being only λ/3.5 (at 500 MHz) in diameter and height making it the smallest among reported or commercially available sinuous antenna at these frequencies.