Two‐Port/Four‐Port Self‐Isolated <scp>MIMO</scp> Antenna With Dual Band for <scp>GSM</scp> ‐900/Sub‐6  <scp>GHz 5G</scp> Applications for <scp>IoT</scp> and Biomedical Applications

ABSTRACT The work presents the design of a compact two and four‐element multiple input multiple output (MIMO) antenna, featuring a self‐isolation capability. The proposed MIMO antenna operates at 0.77–0.96 GHz Global System for Mobile Communication (GSM‐900) and 3.4–3.8 GHz (sub‐6 GHz 5G band) for | S 11 | &lt; −10 dB. The front view of the designed antenna comprises a thin slot that is sandwiched between the patch and an additional radiating element. Further, an inverted T‐shape ground has been incorporated to attain the dual‐band functionality without increasing the size of the antenna. Four antenna elements are placed orthogonally to enhance isolation between the inter‐spaced radiators. It provides high isolation of the order of 32 and 24 dB for the GSM and 5G bands, without the use of a decoupling element. The two‐port and four‐port MIMO antenna occupies a space of 38 × 23 mm 2 and 50 × 45 mm 2 on FR4 substrate with permittivity of 4.40. Furthermore, diversity characteristics have been evaluated based on crucial parameters like envelope correlation coefficient (ECC), diversity gain (DG), and channel capacity loss (CCL) which are computed, and corresponding values for these parameters are as ECC 0.02, DG 10, and CCL below 0.5 bits/s/Hz for the two‐port antenna. However, in the case of the four‐port MIMO antenna, diversity results are as ECC 0.005, DG 10, and CCL is below 0.4 bits/s/Hz, which shows that the diversity performance of the four‐port MIMO is better than the two‐port MIMO antenna. Further, the validation of results and performance parameters of the fabricated antenna are experimentally tested and verified with the simulation results. The proposed work is well suited for Internet‐of‐Things (IoT) and Biomedical applications with SAR values at 0.80 GHz/3.60 GHz for two/four ports corresponding to 0.000153 and 0.712 W/Kg for single‐port and 0.000473 and 0.0483 W/Kg for the four‐port MIMO antenna.