Slot loaded EBG-based metasurface for performance improvement of circularly polarized antenna for WiMAX applications

In this paper, an electromagnetic band gap (EBG) metasurface (MS) superstrate-based circularly polarized antenna for the WiMAX (3.5 GHz) band is proposed. The proposed structure comprises a 2 x 2 slot-loaded rectangular patch MS array that can be perceived as a polarization-dependent EBG MS superstrate. Furthermore, to achieve circular polarization, the proposed antenna has an inclined coupling slot onto the ground with a conventional coplanar waveguide feed line. The proposed antenna has a compact structure with a low profile of 0.037 lambda(0) (lambda(0) stands for the free-space wavelength at 3.48 GHz) and a ground size of 30 x 30 mm(2). The measured results show that the -10 dB impedance bandwidth for the proposed antenna is 34.6% and the 3-dB axial ratio (AR) bandwidth is 6.8% with a peak gain of 3.91 dBi in the desired operating band. Good agreement between the simulated and the measured results verifies the performance of the proposed antenna.