Omnidirectional and Circularly Polarized Waveguide Circular Slot Antenna Array for Satellite Communication

In this paper, the design of omnidirectional and circularly polarized antennas, which can be used in satellite communication, is explained. These antennas consist of circular slotted array placed symmetrically on a cylindrical waveguide. The feeding of this cylindrical waveguide is provided with a special transition from rectangular waveguide to cylindrical waveguide. In order to provide circular polarization parallel metallic plates are attached to the aperture of circular slotted array. As the result of the designs, better than 10 dB return loss is found in the frequency region of both transmitter (around 11.75 GHz) and receiver (around 14 GHz) within approximately 3 percent frequency bandwidth. Besides, there is lower than 1 dB axial ratio in the azimuth plane and lower than 4 dB axial ration in a wide beamwidth of elevation plane. The variation of about 0.7 dBi is observed in the gain at the azimuth plane which provides omnidirectionality at this plane.