Compact Ultra-wideband Circularly Polarized Crossed-dipole Antenna with Wide Angle Coverage

Abstract

|This letter presents a compact ultra-wideband circularly polarized (CP) crossed-dipole antenna with enhanced axial-ratio beamwidth (ARBW) and half-power beamwidth (HPBW). It consists of four modi(cid:12)ed arms which are fed by vacant-quarter phase delay rings to excite CP radiation. Four parasitic elements are utilized rotationally between the dipoles and the re(cid:13)ector. Not only does inducing vertical currents on the parasitic patches excite additional impedance resonance to realize an ultra-wideband operating, but also reinforced radiation is obtained to improve the ARBW and HPBW. The experimental results show that the proposed antenna realizes a (cid:0) 10 dB impedance bandwidth of 134.3% and a 3 dB axial-ratio (AR) bandwidth of 115.0%, while holding a compact volume of 0.25 (cid:21) L (cid:2) 0 : 25 (cid:21) L (cid:2) 0 : 09 (cid:21) L ( (cid:21) L : wavelength at the lowest operating frequency). Furthermore, an HPBW and ARBW of more than 110 ◦ and 160 ◦ are realized within a broad operating band of 67.5% and 55.0%, respectively.