Compact hybrid Sierpinski Koch fractal UWB MIMO antenna with pattern diversity

In this article, a compact 2 element UWB MIMO antenna is proposed. It has a compact size of 40 mm x 20 mm (800 mm(2)). The antenna utilizes hybrid Sierpinski Koch fractal shape as the radiating element. The antenna elements are placed parallel and close to each other. The isolation between the antenna elements is increased by employing a modified stepped ground plane and a reflecting ground stub. The use of stub results in pattern diversity. A U- Shaped slot is etched in the radiating element to notch the WLAN band that interferes with UWB. The antenna performance is measured in terms of S-parameter, radiation pattern and diversity performance. Considering S-11 < -10 dB, the antenna offers an acceptable impedance bandwidth from 2.5 to 11 GHz, with an isolation better than 20 dB over the UWB range. It has a stable omnidirectional pattern. In terms of diversity performance, the antenna has an envelope correlation coefficient (ECC) of <0.1 and capacity loss of <0.1 bps/Hz. The channel capacity of the antenna in the outdoor environment is obtained using Wireless Insite. The channel capacity is found to be 2 Gb/s. The proposed antenna thus can be a good candidate for portable UWB application.