RADIATION PATTERN IMPROVEMENT OF PATCH ANTENNA EMBEDDED IN DIELECTRIC COATING USING ARTIFICIAL SURFACES

Abstract

The use of micro-strip patch antenna is very common in the Öeld of modern communication for conformal applications with broad beam radiation characteristics. The performance of rectangular patch antenna embedded in dielectric coated surfaces signiÖcantly degrades due to the excitation of surface waves in dielectric coating and this is analyzed for various values of dielectric coating thicknesses (6 12mm). The thick layer of dielectric coating causes an increase in return loss and narrow -3dB beam width ( 38 ) in E-plane without signiÖcant change in H-plane radiation pattern of the patch antenna. For the last few years there has been a growing interest for utilizing the electromagnetic band-gap (EBG) artiÖcial surfaces to improve the antenna parameters. The degraded antenna parameters are restored by implementing the artiÖcial surfaces in the form of conducting metal strips loaded over thick layer of dielectric coating of thickness 12mm. The issue of composite radome matching is solved by implementing the frequency selective surface (FSS) over radome. Di§erent planar artiÖcial structures are implemented surrounding the antenna aperture to restore the broad coverage of patch antenna with low return loss. The implementation of the artiÖcially hard boundary in the form of longitudinal metallic strips restores the -3dB beam width ( 102 ) of the antenna in Eplane at the cost of antenna gain. Finally the soft ring over dielectric coating surrounding the antenna aperture is optimized here for broad beam width ( 100 ) in E-plane with increased gain near to 7dB by suppressing the creeped RF energy from thick dielectric coating. 1 ___________