Asymmetric feed circularly polarized broadband printed antenna for wireless communication

In this paper, the design of a new wideband circularly polarized (CP) patch antenna is presented. The design principle of this antenna is different from the conventional monopole antennas. The antenna complies with an asymmetric microstripline feed modified etched rectangular radiator printed on top of a substrate. Another radiator is printed on the bottom of the substrate which acts as a ground plane. The antenna covers a total electrical dimension of 0.180 lambda x 0.318 lambda x 0.005 lambda at the first resonant frequency of 900 MHz. Both the radiators are asymmetrically configured that results in the surface current becomes orthogonal and creates circular polarization. The initial design is simulated in HFSS and after fabrication, the performance is compared with the simulated results. The prototype covers an impedance bandwidth of 118% (900 MHz to 3.6 GHz) under 10dB return loss and axial ratio bandwidth of 101% (1.84 GHz to 5.4 GHz). With the maximum gain of 5.6 dBi, the antenna has a constant growing gain with circular polarization. A detailed parametric study on design and current distribution is carried out to validate the antennas CP mechanism.