Horn antenna on a doppler radar

I want to remove the little patch antenna on the HB100 doppler radar and replace them with horn antenna .Best way to do this anyone?

its impractical.
Tuned microwave systems are tricky.

Horn antennas normally have the mixer diode mounted in the horn at a specific location.

ah ok thx.How can i use the horn (seperately) at 10 GHz?vco?rf generator?

details for the horn ?

This is a homebrew typical setup with gunn diode scource and mixer.

http://jugglingpirate.net/10ghz-x-band-microwave-link/

Radio ameteurs sometimes experiment with this but its very different from standard electronics.

'Components' can have to be made by copper bashing.

If you can get a pre built unit they are not that difficult to use depending on application.

Difficult to scourse though

The manufacturers of that device will have spent 10s of thousands of £/$/€, and thousands of hours of research and development using specialist microwave test equipment to develop their product.

You come along and try to "improve" it's performance, presumably with little or no knowledge of microwave techniques.

Do you own a spectrum analyser, and a vector network analyser?

I personally would not consider doing any such modifications, even though I work for one of the world's oldest radar component manufacturers.