Surface wave reduction in circularly polarized microstrip patch antenna mounted on textured pin substrate

In this paper the work is presented on improvement of radiation characteristics in circularly polarized rectangular patch antenna achieved by designing it on textured pin substrate. A microstrip antenna mounted on textured pin surface has been developed that is characterized by high surface impedance. This surface does not support propagation of surface waves, but reflects these waves in the forbidden band gap. The cylindrical metallic obstacles embedded in the substrate are placed in a square grid array in the proposed design. The parametric study of the designing parameters for the textured pin surface like obstacle spacing and radius of wires has been done. The design has enabled the improvement of -15.7029 dB in isolation, gain enhancement by around 2 dB and radiation efficiency improvement of around 43% along with this axial ratio is obtained to be around 1 which enables it to be appropriately used in satellite communication where circular polarization and superior radiation characteristics are two major requirements. dielectric slab the side lobe radiation occurs that degrades the antenna radiation. The surface wave propagation can be controlled (4) firstly, by micromachining technology in which the substrate below the patch is removed. Secondly, realization of Electromagnetic Bandgap Structures (EBG) is useful in reducing the surface waves. The EBG allows the radiation of space waves at a particular frequency range in which the surface waves propagation is barred as they experience bandgap or stopband. Most predominant method used for surface wave reduction is using artificial dielectric substrate acting as metamaterials (13). Metamaterials are specially designed with modified lattice structure with periodical arrangement of composites. The artificial dielectric investigated in this article is having the unique property of negative refractive index which illustrates the behavior of wave propagation in a different manner. The artificial dielectric incorporated in this article is basically dielectric substrate with embedded grid of cylindrical metallic pins that is characterized by high impedance. The surface waves experience attenuation due to this high impedance surface, thus this medium serves the function of focusing the radiation in the desired direction of antenna's radiation. This way it boosts the radiation and reduces losses due to surface waves. In this article work is presented on a circularly polarized microstrip patch antenna embedded on cylindrical pin structure. The proposed antenna exhibits improved radiation characteristics and superior matching characteristics. This paper elaborates the parametric study of dimensions of textured pin substrate for optimizing the radiation characteristics of the patch antenna which has not been carried out so far. The simulation results are obtained by using Ansoft HFSSv11. II. CIRCULARLY POLARIZED MICROSTRIP ANTENNA The circular polarization forms the basis of signal propagation in space. Microstrip antennas may be designed for circular polarization by adjusting their physical dimensions.