Planar Microstrip-Fed Broadband Circularly Polarized Antenna

Abstract

The design of a printed microstrip-fed patch antenna featuring characteristics of wideband and circular polarization has been proposed. The planar antenna is evolved from a typical monopole consisting of a rectangular radiating patch and a rectangular ground plane. The circular polarization has been obtained by shifting offset the radiating patch in correspondence with the ground. Moreover, a tapered-shaped feeding line has been employed to improve the impedance matching across a wide frequency band and two stubs have been integrated with the antenna to enhance the axial ratio bandwidth. The obtained results have confirmed that, the bandwidths of the proposed antenna with $\mathbf{VSWR leq 2}$ and axial ratio $\mathbf{\leq 3}$ are 140% and 75%, respectively. In addition, the peak realized gain ranges from 1.25 to 3.2 dBi across the operating frequency range.