Gain improvement of higher order mode dielectric resonator antenna by thin air gap

The paper examines the influence of a thin air gap between a dielectric resonator and its ground plane on radiation parameters of the dielectric resonator antenna (DRA) operating with certain higher order modes. Gain improvement of about 1.6 dB is observed for optimal size of the gap, resulting in 13.2 dBi realized gain. Along with gain enhancement, the side lobe level suppression is improved as well. First, the effect is studied using full-wave simulation software and afterwards confirmed by experiments.