Mutual Coupling Evaluation of Dual-Miniaturized PIFA Antenna Array for MIMO Terminals

Because of rapidly increasing demand for high capacity communication services, compact antennas have become center of research interest nowadays and this reduction of size becomes much more important especially when we want to use the Multiple-Input Multiple-Output (MIMO) technology to increase channel capacity, in modern compact devices. In this paper, a design of dual-elements compact Planar Inverted-F Antenna (PIFA) array for handheld MIMO terminal on a ground plane of size 100 mm x 50 mm x 0.8 mm which is compatible with modern stick type mobile phones is presented. PIFA miniaturization techniques is based on the incorporating of meander structure in the main antenna body in order to increase the path of the eclectic current and hence reduce the operating frequency of the PIFA. Overall size is compact than small MIMO antennas available in the literature. The mutual coupling, which is the main factor effects the channel matrix and MIMO system capacity, is investigated in detail for various placements (both position and orientation). The optimal position and orientation for the PIFA antennas inside the MIMO terminal with low mutual coupling which leads to good diversity performance is addressed. Computer aided design (CAD) was carried out by using the Computer Simulation Technology (CST) Microwave Studio package, which utilizes the finite integral technique (FIT) for electromagnetic computation.