Casing effects on the radiation performance of a circularly polarized patch antenna

Miniaturization is one of the prime motives in modern communication systems and can be achieved through size reduction of both components and their packages. Whereas passive components are fairly insensitive to packaging, this is certainly not the case for antennas, as the package is located in the nearfield. The paper focuses on the effects of the casing on the radiation characteristics of a miniaturized patch antenna for circular polarization. Different scenarios involving metallic and dielectric casings with planar dielectric overlays are investigated. A circularly polarized microstrip patch antenna has been designed and investigated with respect to effects introduced by the casing. It is found that a metallic casing severely influences the gain and the axial-ratio bandwidth. It also changes the direction of minimum axial ratio. By placing the patch asymmetrically in the casing, the minimum axial ratio can be improved. A dielectric casing has minimal effect on the radiation properties.