Metasurface Equipped Circularly Polarized Two-Port Filtering Dielectric Reasonator Antenna for 2.5/2.6 GHz Band

Abstract

This article presents the design and analysis of a dual-port Al₂O₃-based filtering antenna, commonly called a Filtenna. The feeding structure of the proposed Filtenna is engineered to generate two radiation nulls within the cylindrical ceramic. The initial single-port Filtenna design is subsequently modified into a dual-port configuration. A metasurface is introduced above the dual-port radiator to enhance performance, enabling the conversion of linear waves into circularly polarized waves. Both experimental and simulation results show a strong agreement, confirming that the developed radiator operates efficiently within the 2.43–2.65 GHz frequency range with a mutual coupling level less than −25 dB. The final design, incorporating the metasurface, achieves a realized gain of 7.5 dBi, while also exhibiting an axial ratio within the frequency range 2.45–2.55 GHz. Outside of the targeted frequency range, the antenna's gain drops significantly, falling below −15 dB on the lower side and −17 dB on the upper side of the band. This makes the aerial design appropriate for WiMAX application.