Zdenek, OK1DFC gave a presentation at the Prague 2002 EME convention.He discussed a new design feed horn, the septum feed. The mechanics of this feed are relatively simple, so I decided to "roll my own", and do some testing with it on the network analyzer.

As a reference I am using a short style VE4MA feed, no choke plate, and a commercial hybrid coupler. This is my reference horn, where I am pretty sure of the circularity being good.