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Mobile Which mobile vehicle model here performs the best?

Discussion in 'CB Antennas' started by Marconi, Oct 7, 2019.

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Which mobile model would you pick as the best performer?

  1. Blazer

    5.3%
  2. PU Truck

    21.1%
  3. Suburban

    63.2%
  4. SUV

    10.5%
  1. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

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    Over the last few years I've made numerous mobile designs using mostly 102" whips as the radiator. In my case I have a limit of 500 segment per model and the mobile body can require 1/2> of the 500 segments just for the body alone. So, I'm limited in making mobile models if the radiator is complicated by having a coil. Coils can require many wires and each wire has 1 or more segments. It all adds up, so I stick mainly with a simple whip antenna.

    Recently I checked several models I had made using various vehicle brands and shapes. I was surprise at the results when comparing the following mobile objects I had created when I added the radiator to the models. I was curious how different vehicles might compare.

    1, the first model I ever made was a Blazer sent to me by Henry HDSP, a member on this forum. He is in the Netherlands. The model he sent me was a small vehicle that basically looks like a PU truck. It had no metal covering over the top of the back...like a real Blazer. The whip antenna is in the center of the cab and the feed point sits at 66" inches above the ground. The Blazer is 15' feet long overall and about 72" inches wide.

    2. is a standard length PU Truck that is 15' feet long, with a 1/4 wave radiator in the center of the cab at 70" inches above ground. All models are set 72" inches wide.

    3. is a Suburban with a 1/4 wave radiator that sits at 88" inches above the ground. It is 17.5' long. I made this particular mobile design based on a similar design created by The DB here on the forum. Here we made our mobile model object with far more wires, as noted. I'm just guessing, but I think DB made this model to see if a more complex mobile object, with more wires closer together, would result in a better and/or more accurate model.

    4. the last model is my original SUV model that is about 15' feet long and 72" inches high above ground.

    The Suburban and the SUV models were positioned as close to the center, length-wise, as necessary to make the patterns...as symmetrical as possible from front to back. The PU Truck and the Blazer are in the very center of both cabs.

    The 102" whips for all models were adjusted to length at resonance.



    I will post these models after a few interested folks vote.

    Below in the PDF file titled, "Mobile models compared" are the full model details and results.
     

    Attached Files:

    #1 Marconi, Oct 7, 2019
    Last edited: Oct 7, 2019

  2. 357magnum

    357magnum Sr. Member

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    Marconi , is this a trick question ? You holding out on us ? Waiting for the results Oh Antenna God ! :whistle:;) 73 & God Bless , Leo
     
  3. 2NC995

    2NC995 DAN

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    I’d have to ask, better in what sense?
     
  4. w9cll

    w9cll W9WDX Amateur Radio Club Member

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    No vehicle is better, all mobile installations are a compromise anyway. More and more plastic means less and less ground plane available.
     
  5. Captain Kilowatt

    Captain Kilowatt Professional Amateur
    Staff Member

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    Not that many people put a full size 1/4 wave on the roof of a P/U truck or SUV. Why not go for a more realistic mounting location like on the rear quarter somewhere or a smaller antenna on the roof? I suppose however everything is relative as far as patterns go as a smaller antenna will have the same horizontal pattern but just lower gain. Might want to try different mounting locations however. I have my antenna mounted on the rear corner of the box on the drivers side of my Tundra Crew Max. The truck is 18 feet long with a short 5 1/2 foot box but LARGE cab area.
     
  6. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

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    Sorry, it was late and I forgot to post the images of these 4 models for you to consider.
     

    Attached Files:

    357magnum likes this.
  7. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

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    No Leo, I was reading a current thread about members opinions on which mobile antennas folks considered to performance the best.

    In my experience, I found most base type vertical mono-pole CB antennas perform pretty similar...if the antenna tips were close to the same height.

    So I wondered, what my Eznec models might predict if I compared the influence of the vehicle style and shape for a mobile antenna setup...instead of just changing the antenna or trying another brand or design.
     
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  8. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

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    In this case, my idea was to compare the patterns produced, and the likley antenna gain and angle for different mobile vehicle designs as the ground plane.
     
    357magnum likes this.
  9. 2NC995

    2NC995 DAN

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    I see. That seems like it could be subjective.

    Either way, I wanted to be an outlier so I voted for the blazer :)
     
    357magnum likes this.
  10. 2NC995

    2NC995 DAN

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    Wow...the antenna lengths ended up all over the map...89.5-105 inches. For a difference or 15 1/2”!!
     
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  11. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

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    True, but this was not a problem solving idea.

    By now most of us probably have some ideas about the problems with modern vehicle construction being problematic for 2-way RF installations.

    These models have limitations as well. I can't be sure this is exactly how a real mobile will work with the model's vehicle body being made up of a bunch of small wires...instead of a smooth contiguous surface of good reflective metal.

    My simple point here, was to show what these Eznec models show that the body shape and size can possibly make more of a difference than most might imagine. I was surprised.
     
    #11 Marconi, Oct 7, 2019
    Last edited: Oct 7, 2019
    357magnum likes this.
  12. sunbulls

    sunbulls Sr. Member

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    Ease of installation is my main concern. Of course the more metal the better. I’ll pass on any small VW Beetles or fiberglass sports cars. The important question in my mind is how easy it will be for me to install a roof mount. Some vehicles have easy access to the roof under the dome light without any major obstructions, others are difficult with cross supports at the desired locations. Removing headliners without damaging them becomes another issue. To immediately evaluate these possible problems, my particular favorite is a full sized commercial van that has a stripped down interior. For a full fledged communications van I want a vehicle with no fancy headliner or side panels. Those details can be added later after all the holes are drilled and wires routed. That way the curtain is pulled back revealing all the mysteries behind it.
     
  13. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

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    CK, this alone was complicated enough. Sure other configurations will make for different results.

    I was going to add a model that I use to run, a 102" whip on my 1993 Chev long bed PU truck. It was mounted in the center top of the tail gate. As a note, back then I never considered bonding that tail gate to the body of the truck and it worked great when I was pointed in the right direction.
     

    Attached Files:

    357magnum and 2NC995 like this.
  14. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

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    I suspect that the radiator length differences have a lot to do with resonance and the antenna being pretty close to the ground.
     
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  15. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

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    Sunbulls, I don't think I can question any of your points.

    When I compared my Eznec models for these vehicles noted...I was surprised at the results.

    I too, always figured the Van like you mention and the Suburban/Explorer type body designs were just as you are likely suggesting, the best performers. The bigger and flatter the roof as the ground plane in a mobile...the better.

    These models just don't show that.
     
    #15 Marconi, Oct 7, 2019
    Last edited: Oct 7, 2019
    357magnum likes this.

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