Stepped Rectangular Patch MIMO Antenna with DGS for Microwave Imaging Applications

This research study proposes a compact MIMO antenna covering the $3-11 \mathrm{GHz}$ band for microwave imaging. It has minimal mutual coupling. It has two radiating elements at the top and a defected ground structure at the bottom, all fabricated on an FR4 dielectric material substrate. To improve the isolation among the MIMO antenna elements without increasing the spatial gap, the ground plane has seven shaped stubs. The MIMO antenna design demonstrates exceptionally low mutual coupling ($\mathrm{S} 21\lt -15 \mathrm{~dB}$) and achieves moderate gain across the entire Ultra-Wide Band (UWB) frequency band. The antenna design exhibits minimal interference among its components, offering a compact structure, wide frequency coverage ranging from 3 to 11 GHz, and improved radiation properties. The antenna’s compact size, broad bandwidth, enhanced radiation characteristics, and moderate gain make it a practical option for microwave imaging applications.