Most gps (goble positioning system) consumer antennas look like a black hockey puck < 2" in diameter. A clean view of the sky is best but have found that they are very forgiving as to mounting positions. Just mount it temporarily where you want it and test. Remember that gps works by receiving signals from acending and descending satellites (24) in a constellation type orbit, so a 'side' view is a good idea.

Six volt guy living in a twelve volt world