On 8/8/2010 1:17 AM, Ian Jackson wrote:
. . .
Over a perfect ground plane, the 1/4 wave will have an impedance of
around 37.5 ohms, and the 5/8 wave around 50 ohms, so the 5/8 is
potentially a better match for 50 ohm coax. Also, the part of the
antenna which does most of the radiating (1/4 wave from the tip) will be
some 6" higher in the sky and, at 460MHz, if the antenna is mounted low
down, every inch of height above the ground counts! Despite this, in
many situations, you may not find much practical difference between a
1/4 and 5/8 wave.

I found only one practical difference. A 5/8 wave mag mount came undone
on the freeway. I've never had a 1/4 wave come off.

Roy Lewallen, W7EL