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Notice the vertical antenna on the truck. I believe this first antenna is referred to as a "dipole", mounted vertically. CB to coax, coax to antenna.

The shell of the truck is fiberglass. Even the front bumper is plastic. Of course there is metal; door frames and the frame itself. The shell is also dipped in a rust proofing solution and I had to clean out threads in the truck that the screws go in. So the screws tap into metal instead of the coating from the rust proofing. I also grounded the mounts that I installed on the truck.

enter image description here

Below, you'll notice the second antenna I mounted horizontally making what looks like a very skinny and upside down capital "T". It's only mounted there, the second antenna isn't wired to the radio or the first antenna.

Will this setup work? Will this create the needed reflective element?

enter image description here

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  • $\begingroup$ Can you post another photo (or drawing) so that we can see where both the existing antenna is, as well as where your proposed second antenna will be, along with its orientation? Also, we don't know what a "Procomm Quad Rod" antenna and its mount look like. $\endgroup$ – Mike Waters Jul 27 '18 at 18:00
  • $\begingroup$ And how much of this truck is fiberglass, Don? If you edit your question and include at many of these details as you are able to, then we likely can re-open your question so that the experts here can help you. :-) $\endgroup$ – Mike Waters Jul 27 '18 at 18:03
  • $\begingroup$ Procomm makes the best stuff in communications equipment. The Quad Rod is wrapped 4 times with wire to simulate a 102" whip antenna. As far as I know, nothing beats it. The guys at Procomm tell me a new antenna is coming out that's even better but I have a hard time believing that's possible $\endgroup$ – user12947 Jul 28 '18 at 2:19
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    $\begingroup$ A matching antenna rod going downward and connected to a balun would create a vertical dipole. $\endgroup$ – hotpaw2 Jul 29 '18 at 18:24
  • $\begingroup$ It looks like you're using 3 black-oxide-coated socket head cap screws that thread into the metal frame. I had problems using those because the black oxide coating acted as an insulator, even when tightened. I suggest that you replace those with stainless steel screws and lockwashers. $\endgroup$ – Mike Waters Jul 30 '18 at 13:31
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as you might guess from it’s name, a dipole consists of two parts, in opposition to each other. A vertical antenna like yours needs an opposing component to act against (usually the earth, or a large plane of metal called a groundplane), and for mobile antennas the ground is usually provided by the metal body of the vehicle. You will notice that the outer part of the coax is connected to the bracket - that would usually connect to the metal body of the vehicle, except that you say your truck is largely fibreglass. This presents us with a few problems, but it’s nothing insurmountable.

If you can get to the inside of the bodywork where the bracket is bolted on the inside, connect some medium-heavy wires to the bolts (they are also connected to the outer of the coax), and run them in a straight line sideways and down in as many directions as you can, for as far as you can. I’d say three wires would be good, four or five better.

These wires will be invisible from the outside, and should help balance the antenna to good effect.

If you have some eyelet connectors like these then these would be ideal, to allow for a good connection to the antenna.

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  • $\begingroup$ Scott Earle, thank you so much! The guys at Procomm said pretty much the same thing. I know it's only citizens band but I paid good money for everything. Plus, I've had a perfectly good radio get fried because I used existing coax on a Freightliner Classic XL that was damaged. Thanks again, it's very much appreciated $\endgroup$ – user12947 Jul 29 '18 at 4:11
  • $\begingroup$ It’s no problem - CB is still radio, the theory is all the same no matter what. $\endgroup$ – Scott Earle Jul 29 '18 at 4:30
  • $\begingroup$ Why not cut those to 1/4 wavelength? Also, if that mount is grounded to the metal frame, these might not be needed. $\endgroup$ – Mike Waters Jul 30 '18 at 13:03
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    $\begingroup$ A quarter wavelength is around 8 feet. I think you’d be hard-pressed to go straight for 8 feet in any direction. Agreed that if the mount already bolts directly to the metal frame then it would largely be pointless $\endgroup$ – Scott Earle Jul 30 '18 at 13:17
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    $\begingroup$ @DonHopper (1) The wire(s) from the mounting bracket to the truck's frame should be as short as possible. (2) A flat SWR like that could mean that you have losses somewhere. It does not always correlate with the radiation efficiency. $\endgroup$ – Mike Waters Jul 30 '18 at 19:34

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