High-gain broadband circularly polarized antenna using microwave lens and metasurface for 5G millimeter-wave applications

This paper presents a new approach for designing a broadband, high-gain circularly polarized antenna for operation in the 5G millimeter-wave frequency bands. Initially, a microstrip patch antenna is designed on a Rogers RT/ Duroid 5880 substrate, employing a diagonally oriented probe feed to excite orthogonal modes for circular polarization. The standalone antenna attains an impedance bandwidth of 19.2% (23.5 GHz −28.5 GHz) with a peak gain of 6.5 dBi. The microwave lens of 13 dielectric sheets is judiciously arranged vertically above the antenna to enhance the radiation characteristics. This configuration effectively collimates the radiation fields, resulting in significant gain enhancement to 11.7 dBi, while maintaining sufficient orthogonal fields at the lower resonant frequencies up to 27.5 GHz. Furthermore, a metasurface layer is incorporated between the dielectric substrates beneath the radiating patch to improve the circular polarization performance. The final antenna configuration exhibits an enhanced impedance bandwidth of 21.6% (24.0–29.84 GHz), a peak gain of 11.53 dBi, and an axial ratio bandwidth that fully overlaps with the impedance bandwidth, making the proposed antenna well-suited for 5G millimeter wave applications.