Design of circularly polarized planar monopole antenna with improved axial ratio bandwidth

A Microstrip fed circularly polarized monopole antenna is been designed at a frequency from 3.5 to 8 GHz. It has a stub and a slit placed orthogonally in its ground layer to facilitate circular polarization. This antenna has 10 dB impedance bandwidth (return loss<-10 dB) of 75% (3.5-8 GHz) and 3 dB axial ratio (AR<3 dB) bandwidth of 8.61% (4.016-4.38 GHz). The ground layer is shaped and extended in a parabolic manner to one end of ground to form beam steering and good directional pattern. It is found that the axial ratio bandwidth is increased to 21.42% (4.375-5.425 GHz) with good pattern steering.