Compact and easy to manufacture dual mode feed horn with ultra-low backlobes

First, a new waveguide transition is presented with the smallest size reported to date with excellent performance over a modest narrow bandwidth of 10%. This transition method is then utilized to create an extremely high-performance modification of the Pickett-Potter dual mode feed horn. The result is the most compact possible feed with a standard rectangular waveguide port. The radiation pattern is fully symmetrical, and the backlobe is typically lower than -40dB. Unlike previous designs, this new feed is the easiest to manufacture because it does not require stepped transformers or multiple diameter cylinders.