Compact implantable MIMO antenna with electromagnetic band gaps

A compact four-unit MIMO antenna operating in the 2.45-GHz ISM band for implantable applications is proposed. Two radiators are integrated on the same antenna, and each radiator is shared by two antenna elements, greatly reducing the overall size of the implantable MIMO system. High isolation between two antenna elements is achieved by etching a “+”-shaped slot in the radiator, extending a stub on the ground and embedding two electromagnetic band gaps (EBG) between the radiator and the ground. The proposed MIMO antenna has a dimension of 18.5 × 18.5 × 1.27 mm ³ . The simulated impedance bandwidths are 18.64% (2.14-2.58 GHz). The simulated maximum mutual coupling is below -15.99 dB at ISM band. The envelope correlation coefficient has been researched and the results indicate the independence between the antenna elements.