Millimeter-Wave Polarization Reconfigurable Circularly Polarized Antenna with Wide Axial Ratio bandwidth

This paper presents a reconfigurable right-handed/left-handed circularly polarized (RHCP/LHCP) antenna with wide axial ratio bandwidth for 5G millimeter-wave applications. Each of the CP elements comprises two parasitic trapezoid patches and three suspended metallic vias, and is excited through an aperture coupling technique with the help of a cross-slot geometry. Two such elements are diagonally connected with the feedline by using p-i-n diodes, which help in achieving the switching between the RHCP and LHCP behaviors. The designed antenna produces wide 3-dB axial ratio bandwidth (ARBW) under both cases, viz. 21.5- 27.55 GHz during LHCP and 23.5- 28.70 GHz during RHCP condition. A good gain of 6.5 dBic over the operating bandwidth has also been achieved for both cases in the broadside direction. The concept is well investigated with the help of parametric variations, surface current distributions, and other critical antenna parameters.