Polarization Converter Surface Integrated MIMO Antenna for Simultaneous Reduction of RCS and Mutual Coupling

This letter provides an effective solution to deal with the radar cross section (RCS) and mutual coupling of the multiple-input–multiple-output (MIMO) antenna simultaneously. A wideband reflective type polarization converter (PC) is designed and its strategic placement in between the antenna elements of the two-element MIMO antenna has been conceived to mitigate these two issues concurrently. The antenna elements of the proposed MIMO antenna are placed at a proximal distance of 0.088 λ from each other. The proposed MIMO architecture ensures a maximum coupling reduction of 46 dB compared to the conventional MIMO across 4.4–8 GHz. The PC surface reduces the reflection of copolarized waves and enhances cross-polarized reflection. A supercell formed by a unit cell of PC and its 90° rotated counterpart causes phase cancellation of cross- polarized reflected waves, which contributes to wideband RCS reduction by a maximum value of 7 dB. The alignment of PC cells in a column between the adjacent antenna elements causes a reduction in the mutual coupling due to introduction of an extra coupling path and cross-polarization conversion. A good agreement between the simulated and measured results validates this concept of the proposed MIMO design with low RCS and mutual coupling.