10 GHz feedhorn with scalar ring, Chapparall Feed.

In order to get back on 10 GHz EME I needed a feedhorn for my 0.25 F/D dish. Not easy to find! Paul W1GHZ paper came to help. The simulations showed there were a number to choose from. Many of the simulations didn’t provide information about the 0.25 F/D. I estimated that the version with a ring width and depth of 0.2 lambda would be the best.

As I have limited access to milling machines the help was called in from the Fablab Midden Limburg they machined it for me after I made the drawing.

As you can see on the video it went very smoothly.

The copper pipe was hammered and squeezed to fit in the WG16 flange. The was rather a simple action and easy to do. Next step would be to make a quarter wave transformer for this. For first tests this should do.