On Sat, 21 Feb 2004 08:08:23 -0800, Bill Turner
wrote:

On 21 Feb 2004 00:07:50 GMT, ojunk (Greg Doughty)
wrote:

My only option is an adjustable angle mount on the hood, rear gate, or mounting
the antenna to the frame under the front or rear bumper?

_________________________________________________ ________

Why not a mag mount on the roof? It will work better than any of the
above. You won't have to drill any holes if you route the coax through
the door jamb. I've done that on many vehicles with no problems at all.
You'd think the coax would get squashed when the door closes, but it
doesn't; at least not enough to matter.

Actually, many of the complaints made to this board often reveal that
both the "thru-the-glass" and magmount are inferior to sheet metal
mounted antennas. Both style certainly work, and well enough for
most, but for those at the edges, they find much better performance
from good solid metallic connections.


On 2 meters, when you put an antenna down low, like on the bumper, two
things happen, both bad: It becomes very directional due to the
blocking effect of the car body, and it's ground wave coverage drops
dramatically. Higher is better.

Higher is always better, but I would dispute that the car body somehow
"shields" an antenna (unless the antenna is butt up against the cab,
say). More often than not, the favored direction (the major lobe) is
found aligned in the direction of the most metal. That is, with a
bumper mount or fender mount, the best propagation is corner to corner
across the car NOT away from the car. In other words, the sheet metal
of the body supports and favors lobe development (instead of the metal
acting as reflector). I've noted this documented by QST since the
'60s.

73's
Richard Clark, KB7QHC

Thanks so much. All great ideas. I once again may go with the mag mount.

Thanks
73
Greg

Higher is always better, but I would dispute that the car body somehow
"shields" an antenna (unless the antenna is butt up against the cab,
say). More often than not, the favored direction (the major lobe) is
found aligned in the direction of the most metal. That is, with a
bumper mount or fender mount, the best propagation is corner to corner
across the car NOT away from the car. In other words, the sheet metal
of the body supports and favors lobe development (instead of the metal
acting as reflector). I've noted this documented by QST since the
'60s.

73's
Richard Clark, KB7QHC

I won't get into the method but it has a lot to do with the frequency and if
the antenna is a full 1/4 wave, 5/8 , or longer co-linear antenna as to what
the patern is. The patern can be over the longest metal path for a 10 meter
whip or it can be "blocked' and go in the opposit direction for an antenna
mounted on one side of the trunk of a car for a co-linear 440 mhz antenna.
This is from the antenna makers diagrams and polar plots. I have observed
by leaving a car in one spot and changing from a 1/4 wave, 5/8 wave and a 6
foot long colinear 2 meter antennas on the same mount that each can have a
diffrant patern , especially where working repeaters and the repeater
antennas are at differant heights. For the areas I am in , I would rather
have a 1/4 wave in the center of the roof , but have settled for a 38 inch
long colinear type dual band antenna on one side of the trunk of my car and
not worried about it.