Design of a Compact Wideband Circularly Polarized Crossed-Dipole Antenna Using a Modified Cavity

A wideband right-hand circularly polarized (RHCP) crossed-dipole antenna with wide impedance bandwidth (IBW) and axial ratio bandwidth (ARBW) is proposed in this paper. A pair of dipoles with modified arms and a novel back-cavity are introduced to enhance both the IBW and ARBW of a conventional crossed-dipole antenna. Simulated and measured results indicate that the proposed structure can improve the circularly polarized (CP) characteristics significantly. The IBW (vertical bar S-11 vertical bar < -10 dB) and ARBW (AR < 3 dB) are 100% and 89.1%, respectively. The total size is 0.4 lambda x 0.4 lambda x 0.15 lambda (lambda being the corresponding free-space wavelength at the frequency of 2.2GHz). With both the excellent CP operating bandwidth and compact size, the proposed antenna is attractive for broadband wireless communication systems.