I've fitted my radar dome on the side of the mast pointing off at about 80 degrees to the port side.  This gets it out of the way of the jib and ensures there is no shadow of the furler on the display.

Someone asked in another thread if this works.  At that point I hadn't wired up and tried the radar.  Hanse UK recommended it to me and I went with that.

I now have and, yes, it works as planned.  The jib doesn't touch it at all.  The radar image is clear all the way around.  The mainsail just touches it when right out on the port side at about the same time as it touches the spreaders - so warning me to bring the sail back in a little bit to avoid wear.

The radar display has an adjustment that rotates the display around so that up is straight ahead. This is part of the standard setup.

My radar is the Simrad 18" one, but I believe this will work with others.

I have looked at many other radars on mast in marinas I've visited and only seen one other with it mounted this way.  However, it seems particularly suited to the Hanse fractional rig with sloped back-spreaders.

(The radar fitted on the port side of the mast)