On Mon, 24 Jun 2013 18:46:46 +0200, Wimpie
wrote:

I overlooked the mobile operation from a car. Of course, when the
antenna is mounted on a metal surface, you don't need radials..

If it's a metal car roof, you don't need radials. Unfortunately, I've
had to deal with verhicles that have a fiberglass roof. Aluminum duct
tape ground plane (on the inside) to the rescue.
http://www.homedepot.com/p/Nashua-Tape-322-1-57-64-in-x-50-yds-Aluminum-Foil-Tape-3220020500/100030120#.Uch4_Ng9pjZ

The fiberglass roof problem is also common in marine VHF (156-163Mhz)
installations. Those tend to use 1/2 wave antennas, which do not
require a ground plane. The automobile version of the 1/2 wave:
http://www.theantennafarm.com/catalog/laird-tech-bb1322w-4470.html?zenid=6bc9236b727ed1e483c9037fb2ac52db




--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558