Multimode hard horn antennas with partly corrugated walls for 20/30 GHz dual-reflector antennas with multiple beams - full 3D simulations and measurements

Paper in proceeding, 2006

We introduce a partly corrugated hard horn, consisting of a smooth-walled horn with an attached longitudinally corrugated outer section. This is used and controlled to design better and shorter single-band horns than otherwise possible. Furthermore, it enables the design of dual-band horns with low cross-polarization and high gain, for multi function use at Ka-band with transmit and receive frequencies in the same antenna. A model of such a dual-band horn was manufactured at Saab Ericsson Space and measured. The design was done by using efficient in-house mode matching code based on homogenized asymptotic boundary conditions for the corrugations. This has been verified by heavy computations using a 3-D FDTD code. The measured laboratory model had too large cross polar sidelobes, but the later extensive computations showed that these sidelobes would have been in agreement with the mode matching results if the number of corrugations was doubled.