Dual-band serpentine-shaped horn with low cross polarization

We have previously realized compact narrow-band horns with low cross polarization (see Deguchi, H. et al., IEEE Antennas Propagat. Symp., vol.2, p.320-3, 2001) and/or high aperture efficiency (see Deguchi, H. et al., European Microwave Conf. Proc., vol.2, p.281-4, 2001), by introducing the "serpentine-shaped taper". The design method for such horns is based on an optimization technique combined with a mode-matching technique (see Olver, A.D. et al., "Microwave Horns and Feeds", IEEE Press, 1994), and it can be applied to developing a horn antenna with higher performance. To achieve wide frequency bandwidth, while keeping the compactness, we propose a new objective function including the spill-over loss and the rotational symmetry of the field. As a result, we have developed a very compact dual-band horn with low cross polarization.