Performance Degradation of Cavity Backed Patch Antenna Due to Dielectric Coating and Its Improvement

The cavity backed patch antenna embedded in dielectric coated structure is presented. The patch antenna is backed by a substrate integrated cavity. The aperture of antenna is surrounded by a thick dielectric material which acts as dielectric coating and significantly deteriorates impedance matching and radiation pattern of antenna. The radiation pattern of antenna is severely degraded due to excitation of surface waves in the surrounding dielectric coating. The proposed electromagnetic bandgap (EBG) structure in the form of via less metallic patches is placed on the surrounding dielectric coating. The EBG structure reduces the propagation of surface waves in the dielectric coating causing improvement in the radiation pattern of antenna. The input impedance matching of antenna is also improved. The simulated results are in good agreement with experimental results.