The reason they show it as a ring is because they don't have any data as to its position relative to the nose of your aircraft. They only know that it is "x" nm away and "y" feet above / below you you (based upon the difference between your transponder altitude and their transponder altitude.
Only the "Zaon XRX"has a directional antenna which plots relative bearings. Unfortunately the display is not wonderful - and the box itself has the antenna mounted on top of the electronics and display and therefore is (IMHO) a bit too large and clunky and in my a/c blocks out a huge chunk of my forward viz.
The directional antenna doesn't have to be that big. The professional directional antennas are pretty much a flat plate - just 3-5 mm high. i think Zaon could do better. They could also separate the antenna from the electronics. You could have a low profile directional antenna on the coaming, with a thin cable feeding to the electronics - which could display on your iPad or Aera / whatever.
There is a company in the US that make a standalone directional antenna system for this purpose - but last time I looked, they were competing with Zaon, not cooperating.
One could knock up a less intrusive directional antenna by just mounting 4 x 2" high ( very thin) antennae on a small aluminium plate - which would be far less intrusive than the 6"x 6" x 4" tall block that is the Zaon. You could use 4 x antennae from the Zaon mini.
Keef - fancy having a go?