Two-Port Metasurface-Loaded Circularly Polarized Al₂O₃ Ceramic-Based Filtering Antenna for 2.5/2.6 GHz Band

In this paper, a two-port alumina-based filtering antenna is designed and investigated. The feeding structure of the proposed antenna creates dual radiation nulls inside the cylindrical ceramic, which in turn produces the filtering characteristics. A metasurface is suspended over the two-port radiator to convert linear waves into circular waves. The designed metasurface also reduces the mutual coupling between two ports by an amount of -15 dB because it acts as a single negative material. Experimental results are in good agreement with simulated outcomes. It works efficiently between 2.31 GHz and 2.62 GHz with an isolation level of more than 35 dB. 3 dB axial ratio is obtained between 2.4 GHz and 2.61 GHz. Out of the frequency band, the gain value is less than -15 dB, while it is 4.28 dBi in the functioning frequency range. Stable radiation properties make it suitable for B41/n41 (2.5/2.6 GHz) applications.a standard retrieval procedure.