Mathematical Framework for Evaluating Mutual Coupling in MIMO Antennas Across Different Sizes, and Frequencies with Design of a Wearable Antenna on Jeans Substrate

Recently, MIMO technology has emerged as a crucial component in wireless communication systems, enhancing data rates and channel capacity. Wearable antennas, designed to function while being worn, represent a new generation of clothing that can sense, process, and communicate data. In this paper, a new evaluation method is introduced to assess MIMO antenna system isolation, taking into account mutual coupling, antenna size, and operating frequency. Additionally, a flexible 2-element 3.5 GHz microstrip MIMO antenna system on a jeans substrate is simulated using CST Microwave Studio software and fabricated. Despite the jeans material being an insulator, the antenna achieves a frequency coverage of 3.5 GHz with a VSWR of less than 2.5 (-6 dB) and a gain of 7.35 dB. The MIMO system exhibits high isolation of -34 dB, outperforming expectations given the λ/2 distance between elements. The use of jeans as a substrate results in a flexible, lightweight antenna that matches the 3.5 GHz frequency with high gain and isolation, despite being an unconventional material compared to traditional FR-4 substrates. a new evaluation method is introduced to assess MIMO antenna system isolation, taking into account mutual coupling, antenna size, and operating frequency.