Compact MIMO Slot Antenna for UWB Applications

A compact four-element multiple-input-multiple-output (MIMO) antenna for portable wireless ultrawideband (UWB) applications is presented in this letter. The proposed UWB MIMO antenna has the compact size of 42 ×25 mm
²
. The microstrip-fed stepped-slot antenna acts as a single UWB antenna element. The UWB antenna covers the wide frequency band from 3.1 to 12 GHz. High isolation ( ≥ 22 dB) is achieved between the UWB antenna elements without any decoupling network. It is due to inherent directional radiation properties of slot antennas (SAs) and their asymmetrical placements. The measured impedance bandwidth of UWB MIMO antenna is from 3.2 to 12 GHz with the isolation better than 22 dB over the entire UWB spectrum. The envelope correlation coefficient (ECC) as well as channel capacity loss (CCL) are investigated, and they are within their acceptable limits.