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CB Ground Plane With Fiberglass Body?

Discussion in 'Truck Talk' started by dhalltoyo, Apr 24, 2008.

  1. dhalltoyo

    dhalltoyo New Recruit

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    The new truck is comprised of a GM cutaway van body and a fiberglass cargo box.

    The cutaway van roof is also cut out and that area is fiberglass too.

    So where do I mount a CB antenna for the best reception?

    I thought about a full length whip off the metal rear bumber.

    What say the EO Engineering Department?
     
  2. Turtle
    Devilish

    Turtle Administrator Owner/Operator

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    All you're gonna need is a No-Ground Plane antenna kit (Firestick makes good ones, as does Wilson). Motorhomes, boats, most 18-wheelers, they don't have metal bodies anymore, and No-Ground Plane antennas work well. You can mount it on the mirror, the bumper (tho the entire van seems like an awful lot that the signal is gonna have to pass through to get out), or on the roof. A really good spot, actually, would be on the vertical side wall above the driver's door on that slope.
     
  3. davekc
    Amused

    davekc Senior Moderator Staff Member Fleet Owner

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    Agree with Turtle. Boat antennas work real well.
     
  4. EASYTRADER

    EASYTRADER New Recruit

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    I don't know about boat antennas but ship antennas are grounded to the water through the hull. Ground plain antennas do work better than non-ground plain antennas, but they do require proper grounding to get the SWR right. I have a metal mirror mounts but they were not grounded to the frame of the truck which puzzled the heck out of me, so I ended up running a separate ground from the antenna to the door, which fixed the swr.

    So if push comes to shove you can mount the antenna anywhere you want and the run a separate ground to a steel part of the vehical.

    The point is to get the swr right so you don't burn up your radio so whatever you do make sure you check that.
    The firestick website has plenty of info on how to install an antenna right.
     
    Last edited: Apr 24, 2008
  5. greg334

    greg334 New Recruit

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    Ah Turtle, the last time I checked, tractors were metal.

    Motorhomes are close to what David has, Boats use water as a ground plane and pose a unique situation because there needs to be some conductor to make that connection of the water and the antenna system.

    A ground plane is part of the antenna system to act like a reflector. Trucks use the cab/sleeper as a reflective surface - ground plane, Vans and cars use the roof.

    Firestik seems to think that aluminum is not a reflective material, funny that all base antennas are made out of aluminum.

    Motorhomes with a fiberglass roofs pose two problems, one is many have a rubber roof coating and the other is that that many lack a real metal structure to mount the antenna on it. I don't remember if it is fleetwood or another manufacture that uses no metal in the roof.

    The antennas that they sell are not really that great in comparison to other configurations. They claim great gain but....

    I did see someone take a short antenna, like a K40 and used a three foot square piece of 22 gauge metal plate mounted inside of the box and grounded to the chassis and the antenna was mounted to the metal plate through the roof giving enough ground plane surface area. The metal also reinforces the fiberglass roof so the stress does not crack the roof.
     
  6. highway star
    Mischievious

    highway star Veteran Expediter Owner/Operator

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    My M2 is fiberglass. The guys at Exit 99 in Anna, Oh replaced one of the mirror mount bolts with a stud and mounted the antenna to that. They tried several antennas and got the best match from a Wilson 2000. It's not 1:1, but it's not too bad.
     
  7. greg334

    greg334 New Recruit

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    Seriously..... your M2 is a complete fiberglass cab?

    I saw one ripped part from an accident and it wasn't all fiberglass or did I miss something?

    Beside the website and Turtle said 18 wheelers.
     
    Last edited: Apr 24, 2008
  8. highway star
    Mischievious

    highway star Veteran Expediter Owner/Operator

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    The skin is fiberglass.
     
  9. greg334

    greg334 New Recruit

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    Well you may be right but I looked at my M2 body manual and see some parts of the cab being fiberglass, but there is metal there.
     
  10. Moot
    No Mood

    Moot Veteran Expediter Owner/Operator

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    David, I like your idea of a full wave whip mounted on the rear bumper. With a roll up door it shouldn't be a problem.

    I have a 36" tune-able steel whip on a bracket that is screwed to the inside of the driver's side fender and sticks out between the hood/fender gap. This setup works great for me and allows me to park my van inside my garage. When I get a chance I will shoot and post a pic.
     
  11. dhalltoyo

    dhalltoyo New Recruit

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    Moot,

    I have seen that bracket advertised on the web.

    The guys at Movin' On Electronics (Exit 99/I-75) even suggested that bracket when I talked with them yesterday.

    They did the roof mount on the current van. It gets excellent reception. All the cables were completely hidden. It is a very professional installation.
     
  12. Dreamer

    Dreamer Administrator Charter Member

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    Dave,
    Wanted to throw a couple more ideas at ya.

    An antenna off the rear bumper will work, but I wouldn't go with a 102 steel whip. While they outplay most antennas, they are a pain... every branch, drivethru, etc will cause it to sway wildly, turning it into a weapon.. believe me I know.. LOL. A better idea would be a long fiberglass whip on a steel flat bar coming off the side of the rear bumper... like this one.

    MODEL T655 Horizontal Antenna Bumper Mount - eBay (item 150239135411 end time Apr-28-08 18:16:10 PDT)


    Alternatively, you could run a side mount on the side of the box, and run a 'no ground' 4 foot fiberglass antenna. I would mount it right behind your side door, and just high enough to get the tip over your box. It would require 3 holes.. 2 for bolts, and one for the coax to run thru.

    FIRESTIK MKM2 CB or Ham Radio Antenna SIDE MOUNT New - eBay (item 360045755654 end time Apr-29-08 20:20:00 PDT)



    Dale
     
  13. Packmule

    Packmule New Recruit

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    David,
    I too have a lot of fiberglass on the Packvan roof as you do on yours. For what its worth, my solution was to go to Junk Shack....I mean Radio Shack and purchase a glass mount antenna that I mounted just above where the rear view mirror would have been, close to the headliner, so I could hide the coax in the headliner and run it down the side of the windshield moulding to under the dash. The antenna mounts on both sides of the glass with a special adhesive and has a tunable SWR adjustment on the inside part. This is the same type that was used for Car Phones years ago and normally mounted on the rear window.
    Mine works great! Price was about $24.95 if I remember correctly.
    I don't run any power on my CB so I don't know how it would work for that type application, but just normal CB Transmission it is Great.
     
  14. maybe_driving

    maybe_driving New Recruit

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  15. Moot
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    Moot Veteran Expediter Owner/Operator

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    Inside fender mount:
     

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