This work presents the design and analysis of a high-gain, flexible two-port four patch MIMO antenna system integrated with a Frequency Selective Surface (FSS) for advanced wireless and wearable applications. With a thickness of 0.8 mm, a relative permittivity of 2.5, and a loss tangent of 0.023, the felt substrate on which the antenna is constructed ensures mechanical durability and flexibility appropriate for body-conformal settings. A T-shaped decoupling structure composed of reflective type FSS unit cells is placed between the antennas for mitigating the mutual coupling between them. However, the gain of the antenna is not significant. A band-pass FSS is therefore placed above the MIMO antenna in order to improve it’s radiation characteristics and reduce out-of-band interference which enhances the spectral selectivity of the antenna, resulting in increased gain. The FSS superstrate strengthens directional beamforming which improves the isolation between the antenna elements in the 20–32 GHz range. The integrated antenna-FSS system achieves a maximum isolation of 45 dB between the antenna elements over the band 20–32 GHz. An envelope coupling coefficient of lower than 0.002 is obtained with channel capacity loss (CCL) lower than 0.1 bits/s/Hz. Measured results bear strong correlation with simulated results. The designed antenna poses out to be an effective biosensor as validated by its S-parameter characterization on human hand. Maximum SAR is computed to be 1 W/Kg per 10 g of human tissue. Further the S parameters of the fabricated antenna have been measured in proximity to plain water and sweet water., which shows a deviation in it’s resonant characteristics, thus disclosing it’s sensing attributes.
Aishwarya et al. (2026) studied this question.