Ground Plane / Antenna Problems...Need Help

[Shortwavewave]

I read and read and read about ground planes and ways to set up antennas but i just dont understand ...

Heres the thing Im transmitting on 11meter (CB) In my car i use a moblie magnunt mount Wilson 1000, Aprox. $$80

Ive took that antenna and put it on a roof made out of metal(bigger than the car) but its sucks on the roof , this i dont understand

I also have a Saturn CB(requires no ground plane) antenna which is about 30 bucks so tell me why this 30$ antenna works better than the $80 Wilson on a ground Plane...

But the Saturn still doesnt work as good as i want, can some one please explain this to me and PLEASE TELL ME A GOOD >>>>> NO GROUND PLANE ANTENNA<<<<

PLEASE I BEG OF YOU ALL

 

[iMONITOR]

Ive took that antenna and put it on a roof made out of metal(bigger than the car) but its sucks on the roof , this i dont understand

The large metal roof is most likely acting like a shield against reception, and either reflecting, or absorbing your signal when you transmit.

 

[k9rzz]

Is the feedline good? Double check the connectors?

John K9RZZ

 

[bayrisch]

What kind of metal?

What kind of metal is your roof? A mag-mount antenna normally uses the roof of your car as the ground-plane. If there's not a good electromagnetic connection, you're going to get a poor ground. Aluminum, for example, is a decent conductor of electricity but reacts much differently to magnetic currents. Your antenna is going to depend on a good electro-magnetic coupling for the ground-plane to work to its desired effect. The way you are describing this, I'll bet your antenna would work much better on a cookie sheet than on your roof...you could actually attach your own radials to the "ground" part of your antenna and put the antenna on your roof and do just fine. Are you using the same coax to feed your antenna on the roof as with your car? If you're not and the type of metal your roof is made of is not a factor, then the first place I would look is your coax connectors.

Mark
WØBG

 

[prcguy]

So far we have comments that claim the ground plane under the mag mount (required for proper operation) is either shielding, absorbing or reflecting reception and that a mag mount will not work (as an antenna) on aluminum. Whats next, the type of tires on the car will affect antenna gain??
prcguy