Optimal design of mushroom-like EBG structures for antenna mutual coupling reduction in 2.4 GHz ISM band

A double element 900 bent monopole antenna system with mushroom-like electromagnetic band-gap (EBG) structures introduced between elements has been studied in this paper using a Finite Element Method (FEM) in order to demonstrate the concept of EBG mutual decoupling. The EBG structures were designed to have a band gap centered around the bandstop frequency of 2.45 GHz. The mutual coupling coefficient s21 was simulated over a range of frequencies around the band gap for some specific designs and electric field distribution on XY plane for optimal EBG design was also computed. Inserting a number of five EBG unit cells with patch sizes of 8 mm, gap between patches of 4 mm and vias cross sectional area of 3.515 mm2, the mutual coupling between antennas improved from -24 dB to -37.4 dB at bandstop resonance frequency of 2.45 GHz.