CPW-fed broadband circularly polarized microstrip rectangular slot antenna with triangular fractal slots in tuning stub

Abstract

A rectangular slot antenna fed by coplanar waveguide (CPW) for broadband circular polarization is presented. Two circular arc shaped grounded perturbation is introduced at diagonally opposite corners of the rectangular slot to obtain wide axial ratio bandwidth. The axial ratio bandwidth is further improved by using a triangle fractal slots in tuning stub. This slot antenna with triangle fractal slots in tuning stub has been designed and optimized on a FR4 substrate with dielectric constant ε4= 4.3 and substrate thickness h=1.53mm. The simulated results of this antenna exhibits impedance bandwidth 151.79% from frequency range (1.93GHz-12.18GHz) at VSWR ≤ 2 throughout this band and axial ratio band width 39.34% from frequency band (3.6GHz-5.45GHz) at AR ≤ 3dB. The simulated radiation patterns of this antenna are Omni-directional in H-plane and Bi-directional in E-plane.