High-isolation broadband 12-port X-band MIMO antenna with via decoupling, polarization conversion, and RCS reduction

This paper presents a novel compact 12-port SIW based MIMO antenna based on a hexagonal slot element operating in the 10.2–11 GHz frequency band. To enhance isolation, via integration is employed between horizontally placed elements, resulting in a 6 dB improvement in isolation between Port 1 and Port 2 and a 2 dB improvement between Port 1 and Port 5. Additionally, the incorporation of a polarization converter extends the bandwidth to 10–11.8 GHz while achieving an axial ratio below 3 dB in the 11.35–11.65 GHz band. The proposed antenna exhibits a high gain of 14 dBi, with an overall efficiency exceeding 96%. Furthermore, the radar cross-section (RCS) is significantly reduced by 18 dB, enhancing stealth performance. The envelope correlation coefficient (ECC) remains below 0.2 across the operating band, ensuring excellent MIMO performance. The proposed design demonstrates promising potential for high-performance MIMO applications, offering improved isolation, enhanced bandwidth, and superior radiation characteristics.