High isolation frequency-reconfigurable UWB-MIMO antenna with on-demand WiMAX band elimination

Abstract

In this article, a planar dual-element frequency reconfigurable multiple-input multiple-output (MIMO) antenna for ultra-wideband (UWB) applications is studied. The frequency band can be switched between UWB operation and single band rejected UWB performance using a pair of PIN diodes in the MIMO configuration. The presented antenna is comprised of two similar slotted circular radiators, having tapered microstrip feedlines and separate partial ground planes. An RT/Duroid 5880 substrate with size 54 × 54 mm² is used for the design purpose. Rotational symmetry between the radiators and diagonally oriented t-shaped decoupling structure behind the substrate have been utilized for high isolation purpose. The designed MIMO antenna exhibits UWB performance in mode 1. In other mode, the antenna operates in the frequency range 2.46–10.44 GHz with Worldwide Interoperability for Microwave Access (WiMAX) band rejection. Thus, the MIMO antenna exhibits on-demand single band rejection behavior depending on the switching conditions of the diodes. The measured isolation is greater than −20 dB in both the modes. The presented MIMO configuration possesses compact and planar geometry with high gain, good isolation, ultrawideband performance with reconfigurable band elimination, high efficiency and efficient diversity performance parameters. The suggested antenna is a good choice to be utilized for portable UWB MIMO applications.