CMA-Guided Co-Design of Antenna and Metasurface for Dual-Circular Polarization at Millimeter Wave

Abstract

This paper presents a higher order mode (HOM)-based dual circularly polarized antenna design for millimeter wave applications. The main radiating element is a SIW cavity-backed antenna with curved slots, and a 4 × 4 array of square patches, is utilized as a metasurface to enhance the overall antenna performance. Characteristic Mode Analysis (CMA), is utilized to identify the appropriate modes and ensure the required phase relationship between them. CMA is also applied to the metasurface to adjust the phase behavior over a wider frequency range, enabling bandwidth enhancement. The metasurface is positioned at an optimized height so that reflected waves undergo a 180° phase shift, which significantly improves isolation. Moreover, the uniform field distribution over the metasurface contributes to improved broadside gain and effective suppression of cross-polarization. The realized antenna exhibits a high gain of 13 dBic, strong port isolation of 37.8 dB at 30.18 GHz, ARBW of 6.8%, and cross-polarization levels <-29 dB in the broadside direction. Thus, the proposed antenna is well-suited for advanced MMW systems that require dual circular polarization.