I was just wondering, is it possible to focus microwaves using an elliptical mirror?

no, not really, it would just reflect it off into a different direction and not alter it much.

a Concave mirror/reflector would work to concentrate the RF though.

Depends what you mean by elliptical.

The curve on a concave mirror is often part of a sphere because they are easy to make but parabolic and ellipsoidal mirrors are also made.

The mirror that focusses the light from a flash tube onto the ruby rod in a "classic" ruby laser is elliptical. It would work perfectly well for radio waves or microwaves.

it would also be useful to know whether it`s for transmit or receive.

I assumed for reception in my original post, Transmitting is a different focal method again.

Thanks guys, and sorry, I did mean a concave mirror. And it would be for transmitting.

Is the mirror a visible light mirror or a microwave mirror?

 

If it's a microwave mirror then yes you can focus microwaves with it depending on the incoming rays... You can get ray tracing programs (or work threw the maths yourself) to work out what will happen.

 

There's something called the matrix method of optics.

Well, you can use a concave mirror to focus the beam of a transmitter too.