Design of hard horn antenna using both single dominant quasi-TEM mode model and mode-matching

We have presented a simple design of the hard horn antenna, electrically designed to be used as feed in the Ka-band cluster-fed multibeam antenna systems, and which can cover both bands of the system with medium efficiency >75 % and maximum cross-polar level below -25 dB. We have also shown some comparisons between a classical quasi-TEM mode model and an accurate mode matching program, and defined an apex length of the hard horn which may be used for its design. These comparisons indicate that the classical model is, due to the fast computational time and rather good agreement, suitable for initial design and study of the hard horn.