Gain Enhancement of Circularly Polarised Microstrip Patch Antenna using Metasurface

In this paper, a circularly polarized microstrip patch antenna is designed using metasurface as superstrate to achieve enhanced gain, so as to make it desirable for practical communication purposes. A parametric study of the effect of variation in the air gap between two substrates and variation in the truncation length of metasurface patches with antenna characteristics is conducted. The results from the parametric study are used to determine optimized values of the different parameters of antenna to get the optimum results and performance. The design and simulation of the antenna is carried out using CST Microwave Studio 2016 simulation software. The return loss is below -10dB from 6.91GHz to 7.94GHz with an impedance bandwidth of 8%. The gain obtained for antenna without superstrate is 4.33dB. A maximum gain of 6.08dB is achieved at 7.24GHz for proposed antenna with superstrate. A significant increase of 1.7dB in gain is hence achieved by the proposed stacked layer. The axial ratio is less than 3dB within the operating frequency range of 6.91 GHz to 7.57GHz which comes under the impedance bandwidth of antenna. The VSWR is less than 2 within the frequency range of 6.91GHz to 7.57GHz. The proposed antenna prototype has been fabricated and tested using VNA and anechoic chamber facility in order to verify the simulated results. Within fabrication tolerances, the agreement with the simulations has been satisfactory.