Spherical embedded antenna for conformal applications

Abstract

Use of planar antenna for conformal applications is of great engineering utilization; however antenna embedding into conformal shapes needs careful analysis. The cavity-backed proximity coupled microstrip patch antenna for spherical conformal application is analyzed. Dielectric and metallic material is used for the sphere. Coax fed antenna is used for embedding for conformal application. A dielectric cover is placed on top of the surface of the antenna to shield the patch and make the spherical surface continuous. Two types of spherical cuts are used with radii of 2λ and 5λ and thickness of 0.508mm and 7mm. Simulation results including vswr, radiation pattern and gain are provided. The parametric study including the effect of material, thickness, radius and dielectric cover is also discussed for the design. The results indicate that the bandwidth of coax fed antenna exceeds 30 % at X- band and the impedance of the antenna is not sensitive to the spherical radius, however the radiation pattern is affected for different thickness and extent of cut of sphere. The radiation pattern is more stable in case of dielectric sphere with reduced thickness as compared to the metallic sphere with increased thickness, irrespective of extent of sphere cut. The dielectric sphere with increased thickness and metallic sphere with reduced thickness deteriorate the radiation pattern by introducing higher back and side lobes. The effect of dielectric cover is to shift the frequency band towards lower frequencies. Higher gain is observed for metallic spheres. Such an embedded antenna has the potential to be easily used for platform mounted applications like UAV, Missile or satellites.