A Novel Wideband Circularly Polarized Printed Antenna

A circularly polarized printed antenna, capable of operating over an octave bandwidth is designed and fabricated. The design is evolved from classical printed monopole/dipole geometry. It employs a microstrip-line fed rectangular radiator, printed on the top of a substrate. The ground, extended as another rectangular radiator is printed on the bottom of the substrate. Both the top and bottom radiators are asymmetrically configured in such a way that the surface currents on them are orthogonal so as to produce left-hand circular polarization (LHCP). The antenna configuration is simulated using a commercially available EM solver. The simulated and measured results closely match within the operating bandwidth. The measured results show a -10-dB return loss bandwidth of 800 MHz to 4.15 GHz and a 3-dB axial ratio bandwidth of 1.5 GHz to 3.4 GHz. For the designed center frequency of 2.45 GHz, these correspond to 136% and 77% respectively. A parametric study of the design is carried out and the mechanism of circular polarization is described.