A wideband and low-unroundness printed conical equiangular-spiral antenna

In this paper, a wideband printed conical equiangular-spiral antenna of low unroundness is proposed. The antenna, with two arms being printed on the substrate, is complementary itself and fed by a microstrip balun. The microstrip balun, linearly and gradually tapered, is adopted to literally match the balanced structure and the wideband characteristics of the antenna. Simulation results in HFSS are discussed. The unroundness within ±35° is less than 1dB and the realized gain is over 0dB. The impedance bandwidth (VSWR<;1.5) is from 1.19GHz to 2.5GHz, with axial ratio less than 1.58dB. The simulation results demonstrate that this antenna is quite suitable for antenna measurement within this frequency range which fully covers the operating frequency of the satellite navigation system.