A Miniaturized UWB Biplanar Yagi-Like MIMO Antenna System

A novel 2-element ultrawideband Yagi-based multiple-input-multiple-output (MIMO) antenna system is presented based on loop excitation. Half of the driven loop element is implemented on each side of the substrate, which not only reduces the overall size of the antenna by 45%, but also increases its bandwidth significantly. The center frequency of operation is 5.8 GHz targeting WLAN applications. The proposed design has a wide measured bandwidth of 2.401 GHz covering 4.183-6.584 GHz. The proposed compact MIMO antenna system has an overall size of 50 × 80 × 0.76 mm
³
with a single element size of 50 × 40 × 0.76 mm
³
. The proposed Yagi antenna has high directional radiation characteristics with a minimum measured front-to-back ratio of 18 dB, minimum measured gain of 6 dBi, and directivity of 6.6 dB using a single director element only, at 5.8 GHz. It has a minimum measured isolation of 17 dB, measured maximum envelope correlation coefficient value of 0.0568, and measured total efficiency above 80% across the band of operation.