Low Electromagnetic Coupling Achievement of a Quad-Element UWB MIMO Antenna Using Miniaturization Technique

Abstract

This research presents a study of a four-element MIMO antenna, whose objective is to design a miniaturized or a reduced inter-elements spacing of a quad–element MIMO antenna that operates in UWB spectrum ranging between 3.1-10.6 GHz, and that characterizes by a reduced inter-element electromagnetic coupling which is due to nearfield coupling and surface current propagation between ports. The proposed MIMO antenna radiating elements are developed from a simple rectangular patch antenna. With the aim to reduce the electromagnetic coupling between radiators and cover the whole UWB bandwidth, diverse techniques are employed, including the employment of the polarization diversity technique, whereas the use of decoupling structures is prevented so as to avoid a bulky antenna assembly. Measurements show that the studied UWB MIMO antenna is characterized by a good compactness whose dimension is about 31×31×0.8 mm³, and it offers a -10 dB impedance bandwidth of 3-12.8 GHz, a mutual coupling <-15 dB, correlation coefficients<0.3, a diversity gain of about 8.75 and a total active reflection coefficient less than -12 dB. Results prove that despite of the miniaturized size of the studied antenna assembly and the disuse of decoupling mechanisms, the presented antenna provides potential diversity performances for use in UWB applications.