Compact near zero index metasurface lens with high aperture efficiency for antenna radiation characteristic enhancement

Abstract

In this paper, a high gain, aperture efficient, low profile compact, near zero index (NZI) metasurface (MS) lens antenna with enhanced radiation characteristic is proposed. A high-performance transmissive MS is designed by using modified double circular ring resonator as unit cell with measured 3 dB transmission band from 8.80 to 11.90 GHz. It is observed that a triple layer stacked MS lens has the maximum ability to converge the electromagnetic radiation. The focusing mechanism of multiple stacked MS is studied by using measured E- and H-plane radiation pattern plot and H-Field distribution. A high gain low profile antenna is designed by placing the proposed small single surface NZI MS lens over a microstrip patch antenna acting as a microwave source. The proposed NZI MS lens is found to increase the measured gain of E- and H-plane by 10.70 dB in boresight direction at operating frequency 10.15 GHz. The front to back ratio is improved by 8 and 3 dB in E- and H-plane, respectively. The proposed MS lens antenna is able to achieve a broadside gain of 97.50% of the maximum gain achieved due to ideal effective radiation surface.