The Impact of Slow-Wave modes on the Radiation Performance of a Corrugated Horn Antenna

Corrugated horn antennas offer many advantages compared with other waveguide radiators. A major disadvantage which is inherent with the design of a corrugated horn is the fact that slow-wave modes may exist within the horn antenna. In this paper far-field measurements of a W-band horn antenna are presented. The experimental data is compared with simulated data to confirm the presence of slow-wave modes. The analysis is completed by determining the waist, the gaussicity and the phase center location of both the experimental and model data. Finally a redesign approach is proposed which suppresses the slow-wave modes and therefore increases the usable bandwidth of the horn antenna.