Compact multiple-input multiple-output antenna with low correlation for ultra-wide-band applications

A compact multiple-input multiple-output (MIMO) antenna with a small size of 26 × 55 mm² and low correlation has been proposed for the ultra-wide-band (UWB) applications operating over a frequency range of 3.1-12.3 GHz at -10 dB. The MIMO antenna consists of two identical elements each of which has a planar radiator with microstrip-fed over half-sized ground plane. The antenna elements are placed orthogonally to achieve a good isolation between the two input ports. The antenna´s characteristics such as the bandwidth, isolation, radiation pattern, peak gain and surface current distributions have been investigated. Moreover, diversity performance in terms of envelope correlation coefficient and mean effective gain has been analysed. Furthermore, a parametric study has been carried out to provide more design information. An arrangement with quad-elements has been designed for MIMO operations, as well. The simulation and measurement results show that the proposed antenna has an impedance bandwidth larger than the frequency range of UWB with low correlation and high diversity performance. The proposed MIMO antenna has been compared in detail with the previous works reported elsewhere in terms of antenna size, geometric complexity, bandwidth, mutual coupling and use of additional structure to obtain more isolation. From this point of views, the antenna is more preferable than other suggestions.