An Improved Broadband Circularly Polarized Cross-Dipole Antenna With An AMC Reflector

In this paper, we present an improved design method to significantly reduce the volume of circularly polarized (CP) cross-dipole antenna. Unlike the commonly used approaches, the distance between the antenna and the reflector is largely narrowed to only 0.13 lambda(0) in this work. The proposed cross dipole antenna achieves low profile and broadband characteristics by using stepped rectangular patch arms, parasitic strips and artificial magnetic conductor (AMC). And CP radiation for the proposed antenna can be generated effectively by connecting two arms of each dipole via a vacant-quarter ring. The overall size of the proposed antenna is 0.88 lambda(0) x 0.88 lambda(0) x 0.13 lambda(0). Simulation results show that a broadband impedance bandwidth (for S11 < -10 dB) of 473% (1.81 to 2.93 GHz), a wide 3 -dB AR bandwidth of 253% (2.16 to 2.78 GHz), the peak gain of 7.8 dBic and the average CP gain of whole operating frequency band of 7.5 dBic are obtained.