An Integrated Four-Element Slot-Based MIMO and a UWB Sensing Antenna System for CR Platforms

This communication presents a novel integrated antenna system for cognitive radio (CR) applications. The design consists of a compact four-element reconfigurable annular slot-based multiple-input-multiple-output (MIMO) antenna system integrated within an ultrawideband (UWB) sensing antenna. All the antenna elements are planar in structure and designed on a single substrate (RO-4350) with dimensions $60\times 120\times 1.5$ mm
³
. The frequency reconfigurable slot-based MIMO antenna system is tuned over a wide frequency band from 1.77 to 2.51 GHz while the UWB sensing antenna is covering from 0.75 to 7.65 GHz The proposed antenna system is suitable for CR enabled wireless devices. The envelop correlation coefficient did not exceed 0.248 in the entire operating band of the MIMO antenna part. The maximum measured gain of the MIMO antenna is 3.2 dBi with a maximum efficiency of 81%.