Closely packed millimeter-wave MIMO antenna arrays with dielectric resonator elements

The design of a millimeter-wave (mm-wave) dielectric resonator (DR) multiple-input-multiple-output (MIMO) antenna system is presented. The MIMO structure consists of four arrays each radiating in one of four opposite directions. Each array is composed of four cylindrical DR antenna elements (cDRAs) operating at 30 GHz with a fractional bandwidth of at least 6.7%. The elements are fed via slot coupling which isolates the radiating elements from the feeding network. Also, each array in the MIMO system has a fixed and tilted beam enabling good MIMO operation which results from a passive microstrip-based feed network. The four arrays are closely packed in two pairs with each pair occupying only 20 × 10 × 3.1 mm3 on the top layer of the PCB. The proposed antenna can be used for compact mobiles that support 5G data links.