Quad-Port MIMO Antenna Design with Low SAR for 3.5 GHz 5G and 5.8 GHz ISM Bands

A 4-port MIMO antenna with a low specific absorption rate (SAR) is presented in this paper for 3.5 GHz 5G, and 5.8 GHz ISM (Industrial, Scientific, and Medical) band applications. The antenna is developed on a 0.252 mm thick Rogers 5880 substrate with a compact size of 36.2 mm x 36.2 mm. The designed antenna offers a bandwidth of more than 100 MHz (3.47 - 3.58 GHz), and 350 MHz (5.64 - 6.01 GHz) at 3.5 GHz and 5.8 GHz bands, respectively. The antenna also provides a good radiation efficiency higher than 90 % within the functioning frequency bands with a peak gain of 2.01 dBi and 1.71 dBi at 3.5 GHz and 5.8 GHz, respectively. To check the radiation effect of the antenna in terms of SAR on the human tissue, a 3-layer biological tissue model is created. And, the SAR value of the designed antenna is calculated. With 125 mW of supply power, the proposed antenna shows a SAR value of 1.92 W/Kg and 0.465 W/kg averaging on 10g of tissue, while the antenna is positioned 10 mm away from the 3-layer human tissue model. The suggested antenna is a good fit for dual-band MIMO systems operating at sub-6 GHz based on its overall performance metrics.