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Thread: Question on mounting 2m antenna on plastic big rig

  1. #1
    Master Navigator W5BRM's Avatar
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    Question on mounting 2m antenna on plastic big rig

    Been having a helluva time trying to install a 2m antenna on my Freightliner Cascadia. I know we got a few current/retired drivers here hopefully can help

    What I have is basically a plastic truck. It's all composite materials or outright plastic. As it is a company truck, I cannot make holes or modify the truck in any way. There are no West Coast mirror frames so I am using a Wilson mount to attach to the plastic foldover mirror frame. This frame is all plastic and has no bonded connections in it anywhere to help make an antenna work right. there is nothing to bond to inside the frame and the rest of the door is composite material. This poses a problem.

    What can I do to mount a 2m antenna? So far, I've tried Hustler SF2 5/8w antenna with no luck. Tried a Half Wave with no luck. Both failed due to needing grounding/bonding to the truck, which I can't do

    I have been trying to look into "no groundplane 2m antennas" but can't find any info on whether they will work on a plastic truck. I know the theory but can't find any sort of explanation or construction history on how these work.

    When the term Ground Plane is used, are they speaking of having a grounded bonded connection to the body/frame of the truck? or are they speaking of having an actual ground plane attached to the antenna? Will a "No groundplane" antenna actually need no groundplane or any sort of grounding/boding to the truck to work? If not, then what is the idea on how they work? To me, the term "No Groundplane Antenna" is an antenna that will work in free space without any sort of grounding, bonding or connection to any sort of metals.

    As it looks like most of these type of antenna are 1 piece units, How do they balance out? Is the coax shield the other half of the antenna or is something else at work here? If so, does this mean I have to use a "tuned" piece of coax to provide the counter to the main antenna? Half wave at 146mhz is about 39 inches and thats a way short piece of coax to use in a mobile instance.

    Help would be appreciated. My GoogleFU is weak today.

    Thanks
    .

  2. #2
    Orca Whisperer PA5COR's Avatar
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    Everyone of those antenna's needs a groundplane, one wire of about 50 cm running at a 180 degree angle will do, otherwise the coax will be used as ground plane.
    That is less good, so if it is possible at the antenna feedpoint to connect a 50 cm wire do try so.

    What we did in plastic top cars was glue in a 50 cm x 50 cm square aluminium foil and use that as ground plane but you can
    't drill holes in it, so that is out.
    "If the Republicans will stop telling lies about the Democrats, we will stop
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  3. #3
    "Usual Suspect" WZ7U's Avatar
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    Ohh, I gotta noodle that one for a while. I bet there is no way to have a dangly piece of wire as a counterpoise, is there?

    Off to think about this....

    Like that post was...
    Moving on, my posts are not helpful

  4. #4
    Orca Whisperer PA5COR's Avatar
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    Look for a wire with isolation in the colour of the mirror, tape it with same colour tape to the mirror frame.
    That way it won't be a real eyesore, needs to be only a thin wire anyway, so you are making an open dipole with it with the wire acting as 2nd half of the dipole.
    "If the Republicans will stop telling lies about the Democrats, we will stop
    telling the truth about them." - Adlai Stevenson (1900-1965)
    “I’m not liberal/conservative, I’m anti-idiotarian.”
    At some point in the last 20 years, the left moved to the center, and the right moved into a mental institution

  5. #5
    Administrator N8YX's Avatar
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    Does your cab have an air dam overtop it and the sleeper?
    "Everyone wants to be an AM Gangsta until it's time to start doing AM Gangsta shit."

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    Whacker Knot WØTKX's Avatar
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    "Where would we be without the agitators of the world to attach the electrodes
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  7. #7
    Master Navigator W5BRM's Avatar
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    Quote Originally Posted by N8YX View Post
    Does your cab have an air dam overtop it and the sleeper?
    I drive a "condo". I have a dome but not an actual hollow air dam. Wish I did as I could just wind counterpoise all over it...lol.

    I think I'm going to try COR's suggestion and try to add counterpoise on the actual mirror housing frame.
    Last edited by W5BRM; 05-10-2017 at 06:24 AM.

  8. #8
    Master Navigator W5BRM's Avatar
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    Quote Originally Posted by WØTKX View Post
    Unfortunately, the mount style I'm stuck using is too small and oriented 90° the wrong way. Plus the jpole needs space around it and it would be right next to tge cab so it wouldnt work. The tuning stub would ne the issue

  9. #9
    Conch Master W7XF's Avatar
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    FreightShakerCascadia? Dunno about that one, due to the ground (?) being all about non-existant. The best attempt I'll guess is to mount it to the frame rail on the left corner of the back of the cab. At least you'll some semblance of a ground. Of course, YMMV.
    Encrypt everything. Even if you have nothing to hide. It increases the noise floor.

  10. #10
    Whacker Knot WØTKX's Avatar
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    Yea, too bad. I have that Arrow antenna, and it kicks ass.

    Build a twin lead jpole and stuff it in some PVC pipe?
    I've built/elmered these for new hams
    Suspend it inside of PVC with some fishing line.

    http://www.qsl.net/wb3gck/jpole.htm

    "Where would we be without the agitators of the world to attach the electrodes
    of knowledge to the nipples of ignorance?" ~ Professor "Dick" Soloman



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