Millimeter-wave antenna with wide-scan angle radiation characteristics for MIMO applications

A three-element quasi Yagi-Uda antenna array with printed metamaterial surface generated from the array of uniplanar capacitively loaded loop (CLL) unit-cells printed on the substrate operating in the band 25-30 GHz is proposed. The metamaterial surface is configured to provide a high-refractive index to tilt the electromagnetic (EM) beam from the two dipole antennas placed opposite to each other. The metamaterial region focuses the rays from the dipole antenna and hence increases the gain of the individual antennas by about 5 dBi. The antenna elements are printed on a 10 mil substrate with a center to center separation of about 0.5 lambda(0) at 28 GHz. The three-element antenna covers 25-30 GHz band with measured return loss of 10 dB and isolation greater than 15 dB between all the three ports. The measured gain of about 11 dBi is achieved for all the antenna elements. The three antenna elements radiate in three different directions and cover a radiation scan angle of 64 degrees.