This article presents a novel strategy for reducing mutual coupling and Radar Cross Section (RCS) in a 2 × 1 MIMO antenna system tailored for military radar applications. The proposed arrangement involves two identical radiators oppositely arranged with an H-shaped strip placed between the radiators. A wide slot, stub projection, and frequency selective surface (FSS) are engraved on the backside. The overall dimension of the suggested system is 25 × 25 × 1.6 mm3, which resonates at 6.09 and 8.34 GHz with an impedance bandwidth of 6.16 GHz from 2.95 to 9.11 GHz. The isolation (≤ −30 dB) is obtained by incorporating a wide slot and an H-shaped strip between the radiators. A grid of miniature square slots is etched on the rear side of the antenna, leading to an additional enhancement in the isolation and monostatic RCS reduction by more than 25 dB. The diversity gain (DG) and envelope correlation coefficient (ECC) are also examined for the suggested antenna to validate its diversity performance. The congruence between the validated and simulated results is remarkably strong, rendering it a fitting choice for military and airborne devices/applications operating within the C and X bands.