The dual-ridged horn antenna (DRHA) is a workhorse in EMC and antenna pattern measurement labs. Its broad band allows the user to test over a large range of frequencies without changing antennas. Dual-Ridge Horns are a great solution for gain reference, far-field test ranges and reflector feeds for high gain applications.
These antennas came under scrutiny when Burns, Leuchtmann, and Vahldieck showed inj testing the pattern problems of these antennas at the upper end of the band.Their work illustrated that these types of horns have problems with the integrity of the main lobe of the pattern.
While efforts to improve these horns have been concentrated primarily on the 1- to 18-GHz models, DRHAs also cover other frequency ranges. The 200-MHz to 2-GHz range DRHA is required by MIL-STD-461E for both emissions and immunity in the 200-MHz to 1-GHz range.
View the research report fully at https://www.researchgate.net/publication/291894586_The_dual-ridged_horn_antenna