A Wide-band Slot-based Frequency Agile Yagi-Like MIMO Antenna System

In this work, we propose a wide-band slot-based frequency agile 2-layer Yagi-uda-like multiple-input-multiple-output (MIMO) antenna system. The MIMO system consists of 4 identical pentagonal slot-line based active antenna elements reactively loaded with varactor diodes to achieve frequency reconfigurability. The proposed antenna could be tuned over a wide frequency band from 1.5-2.1 GHz. To achieve Yagiuda-like directional characteristics of a slot antenna, a parasitic metallic reflector layer was used below the substrate. This helped in suppressing the back-lobe radiation and thus a front-to-back ratio (FBR) of 5-13 dB is achieved within the entire frequency band of operation. The proposed 4-element design is compact with an overall size of 100\times 100 \times 20 mm ³, and a reflector size of \textbf{110}\times \textbf{110} mm ². The antenna system also shows good MIMO performance with high port isolation and very low envelope correlation coefficient (ECC) values within the operational band.