This radar script scans 360 degrees all around the player and only considers straight-line distances on the X-Z plane. So, the distances in this radar are not affected by any height difference between the player and target GameObjects. The script can be adapted to ignore targets whose height is more than some threshold different from the player's height.
Also, as presented, this recipe's radar sees through everything, even if there are obstacles between the player and the target. This recipe can be extended to not show obscured targets by using raycasting techniques. See the Unity scripting reference for more details about raycasting: http://docs.unity3d.com/ScriptReference/Physics.Raycast.html.