Design of a two-port MIMO antenna with low-mutual coupling based on a Pentagonal-Fractal ring element

Abstract

In this work, a two-element multiple-input–multiple-output (MIMO) 3.5GHz antenna covering the 3.5 WiMAX commercially useful application is proposed and analyzed. The antenna element is based on first-orde rpentagona lfracta lrin gmonopol eantenn afe db ya Y-shaped transmission line. To achieve a compact size, the sides on the pentagonal ring are loaded with a triangular shaped branches oriented towards the antenna center to obtain the fractal ring radiating element. The resulted antenna element, overall dimensions of 15x19mm2 , is fabricated and its reflectio ncoeffici en tismeasu red forexperimen talval-idation. The resulted antenna element is then used to design a two-port MIMO antenna. The MIMO antenna consists of two identical antenna elements arranged orthogonally in polarization diversity configuration. By loading the antenna with arectangular stub, the mutual coupling between the antenna elements is significantl yreduced .Th estu bi sprinted diagonally in the back side of the substrate. The resulted MIMO antenna has an overall size of 31.35x31.35mm2 with better isolation less then -19 dB. The simulated maximum realized gain and maximum radiation efficien cya re1.76dBi and 66.33% respectively. Moreover, the performance of the proposed MIMO antenna in terms of isolation, realized gain, radiation efficien cya ndradiati onpatter nsa restudied.