Wideband circularly polarized reconfigurable metasurface antenna for 5G applications

Abstract

A framework of a metasurface (MTS) - based wideband circularly polarized (CP) reconfigurable antenna for fifth generation (5G) wireless systems operating in the sub-6 GHz mid-frequency range is presented in this article. The proposed structure contains a simple patch antenna, which serves as the primary source, a shorting pin, two ring slots, and a metasurface superstrate. The shorting pin and two ring slots produce perturbation resulting in circular polarization with a narrow axial ratio (AR) bandwidth. A metasurface (MTS) superstrate composed of 4 × 4 rectangular patches stacked over the primary source antenna generates additional resonances that significantly improve the -10 dB impedance and 3 dB axial ratio (AR) bandwidth. Two PIN diodes are employed to alter the circular polarization between left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). The prototype is made using an FR-4 epoxy substrate and has an overall size of 50 mm × 35 mm × 4.2 mm. The antenna has a -10 dB bandwidth of 44 % (4.0-6.2) and a 3 dB axial ratio bandwidth of 28 % (4.2-5.6). It also has a 3 dB beam width of 74° and 85° in the E and H planes, a gain of 7.1 dBi, cross-polar isolation of more than 15 dB, and a unidirectional radiation pattern. The simulated and measured results confirm that the implemented antenna is promising for sub-6 GHz 5G communication systems, particularly cognitive radio, wireless body area networks (WBAN), and satellite communication systems.