Cavity backed embedded antenna on cylindrical surface for conformal applications
The use of planar antenna for conformal applications is of great engineering use, however antenna embedding into conformal shapes need to be carefully studied. The analysis of cavity-backed proximity coupled microstrip antenna embedded in a cylindrical surface is presented. Cavity backed antenna is used for higher bandwidth. A dielectric layer, which is integrated on the surface of the antenna, is designed to shield the patches and make the cylindrical surface continuous. Dielectric substrate Rogers RT/duroid® 5880 with εr =2.2 and metallic material Aluminum is used for the cylinder. Edge fed and coax fed configurations are compared. Based on the ease of manufacturing and testing, coax fed antenna is used for embedding for conformal application. Simulation results including S-parameters, 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. Two types of cylindrical cuts are used with radii of 2λ, 5λ and 10λ and thickness of 0.508mm and 7mm. The results indicate that the bandwidth of edge-fed and coax-fed antenna exceeds 40% and 30 % respectively at X- band and the impedance of the antenna is not sensitive to the cylindrical radius, however the radiation pattern is affected if the cylinder is cut into half or reduced even further. The radiation pattern is more stable in the case of dielectric half cylinder with reduced thickness as compared to the metallic reduced cylinder with increased thickness. The effect of dielectric cover is to shift the frequency band towards lower frequencies. Higher gain is observed for metallic cylinders. Such an antenna can easily be used for platform mounted applications like UAV, Missile or satellites.