CB antenna junk again

[PARAGON]

Originally Posted by Beastmaster

Got a pic to show how it's mounted? I suspect that I know what the problem is, but I need to see how you've got everything.

-Steve

well, No, not right now. there's really no problem. I'm just not sure if I should ground the rack or leave it out of ground. The way the rack mounts to the top, it's not really grounded well to the truck.

The regular roof panel of the truck offers a ground plane and now I have added this mesh and tubular rack on top. I don't have everything wired up, to get a meter on or to test in any way and don't want to disturb the PC on the rack if it would be better for the rack to not be grounded to the truck.

Think of it this way. The base of the antenna is just below the bottom of the rack, which shouldn't make much difference except it's a base-loaded antenna. I have that rack that covers all of the roof and the antenna is centered at the rear-most part of the truck. Should I ground the rack to the truck ground.

[Beastmaster]

That's what I thought. Here's the problem that I see.

Bottom loaded coils on low frequency transmissions will have a tendency to emit more radiation from the coil on upward.

So, if the coil is under the roof rack grid, the majority of the signal will end up being bounced between the ground plane of the roof and the roof rack grid.

If you were to look at a normal vertical antenna from the side, it would emit in a pattern similar to what you would see in a McDonald's arch logo, or similar to a bagel being cut in half abd you create an "m" shaped thing out of it.

When you have the coil between the grid, the propogation will end up getting cut off and you'll end up with only a transmission pattern that is aimed pretty much upward.

The funny thing - grounding the rack will merely add to transmission woes in theory, since you're sandwiching the coil part of the antenna between two actual ground planes.

So, I'd see if I could put the magmount on the grid of the rack, and ground the rack.

[PARAGON]

I don't like you

I was thinking along those lines and was hoping that if the rack wasn't grounded it might offer some difference.

The antenna base stays well protected like it is, but doesn't serve me very well if it's severely limiting my range. Guess it's up on the rack.

[ree]

Originally Posted by PARAGON

...
The antenna base stays well protected like it is, but doesn't serve me very well if it's severely limiting my range. Guess it's up on the rack.

Is this really a fit it in the garage without scraping up the door issue?

[PARAGON]

Originally Posted by ree

Is this really a fit it in the garage without scraping up the door issue?

No not really. I don't run with the antenna on the base all of the time.

The way the antenna is made (and the way I drive off-road) a nice limb would slice it right off at the base because it would wedge at the rear of the rack, even though it's magnetic. I've already tried to tear the old cross bars off a couple of times on the sides of trees. So I am trying to think pro-actively and have the antenna protected, before there was nothing to "hold" it and a limb would just knock it loose and all I would have to do is put it back in place.

But, alas, I get too anal about stupid things like this and overcomplicate it. I should have just stuck it on the rack to begin with and not worried about it.