A Circularly Polarized Shaped Beam Antenna with Isoflux Radiation Pattern

A design of a compact circularly polarized antenna with isoflux radiation pattern is presented. The proposed antenna composes of a cavity backed patch antenna and a shaped dielectric cylinder for achieving a stable isoflux beam radiation. The patch antenna is embedded and placed at the base of the dielectric cylinder. A sequentially-fed excitation is used to generate circularly polarized waves from the proposed antenna. Having optimization, the antenna achieves the isoflux radiation pattern within the beamwidth of about 80 degrees at the center frequency of 7.5 GHz. Meanwhile, the spatial axial-ratio (AR) is less than 3 dB within the beamwidth. The peak gain occurs at the elevation angle of +/- 40 degrees with the value of about 5.5 dBic.