Design of a compact UWB MIMO-diversity antenna incorporating fractal inspired isolation structure with band notch characteristics

In this communication, a new compact ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna with band notch characteristics is presented for wireless application. It comprises of two unique monopole antenna elements sharing a similar ground plane. To reduce the coupling between antenna elements, a modified T-shaped stub equipped with Minkowski fractal shape elements are introduced on the ground plane which in turn establish a good isolation between radiating elements. A band notch is achieved at 5.45 GHz by adding two additional rectangular stubs at 45 degrees where symmetric slots have been etched. The efficiency and gain of the antenna drops significantly at the centre of the notch band which indicates good interference suppression. Results show that the designed antenna delivers widest impedance bandwidth (-10 dB) throughout the operating band of 3.1-20 GHz (of 146% impedance bandwidth) which covers UWB as well as Ku-band. The antenna also produces -18 dB isolation for most of the operating band and -16 dB up to 6 GHz. The optimized antenna is fabricated and tested showing |S-11| characteristics below -10 dB from 3.1 to 20 GHz band. The dimension of the proposed antenna is 18 x 26 x 1.6 mm(3). Results show that the simulated characteristics are in good agreement with the measured counterpart. The designed MIMO antenna is an appropriate candidate for UWB and other wireless applications.