Radiation characteristics of a corrugated circular cylindrical waveguide horn excited in the TE11 mode

The design and experimental studies on a corrugated circular cyclindrical waveguide antenna that is feed-excited in the TE11 mode with suppressed far-out sidelobes are reported. To reduce the spillover in the region theta = 90 deg - 180 deg, an attempt was made to introduce circumferential corrugations on the outer surface of the waveguide wall. The design criterion used was that a minimum of 11 corrugations per wavelength were used, and in all there were 25 corrugations. The reason for selecting 25 corrugations was to ensure that the conduction currents induced on the outer walls of the guide were attenuated substantially and did not contribute to the far-out sidelobes. Measured E-plane and H-plane radiation patterns of the feeds and the corrugated waveguide are presented.