Hidden 2m mobile antenna?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by W8UNX, Apr 1, 2010.

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  1. W8UNX

    W8UNX Ham Member QRZ Page

    I am wanting to install my TM-D700a in my Dodge Magnum, but, for various reasons which we will just shorten to the variable "XYL," mounting a 2m/440 antenna anywhere on the (outside of the) car is a non-starter. Initially, I thought about laying some stiff copper wire in the rain channel on the roof, but that would be darn near horizontal and not likely very useful for 2m repeaters, I'd think.

    In searching the interwebz for ideas, I came across this:

    STI-CO Covert VHF Bumper Antenna

    It consists of a pair of dipole antennas and a coax splitter. The instructions (available elsewhere) show one dipole mounted at the front left corner and one at the rear right corner. The leads are then plugged in to the coax splitter (more of a yoke, really) and then from there in to the radio. $350 seems like a lot for a couple of dioples and a coax section, but maybe I'm overly-frugal.

    So, I'm thinking of building something similar and giving it a go. Before I do, though, I thought I would ask here and see if anyone has done something similar, or maybe has experience with the STI-CO product and can advise on how well this is likely to work out.

    Many thanks and 73s,

  2. KA9MOT

    KA9MOT Ham Member QRZ Page

    Last edited: Apr 1, 2010
  3. W8UNX

    W8UNX Ham Member QRZ Page

    But, they do come with a small roll of butyl tape for affixing the antennas to the inside of the bumper. That has to be worth something. ;)

    Yes, I've seen those. They go on the outside of the car which is not going to work if I want to keep the peace. The idea with those STI-CO dipoles is that they attach behind the bumper fascia and are completely hidden. Thank you for the suggestion, though.
  4. K7JEM

    K7JEM Ham Member QRZ Page

    You might be able to tape a QW piece of wire to the inside of a back window, and put radials down, or use the car body for a ground plane. Any sort of inside antenna will be a compromise, but it should work to some extent. Or copper or AL tape on the inside of the window.

  5. KC7YRA

    KC7YRA Ham Member QRZ Page

    My gut feeling is that you would be disgustingly disappointed with the "behind the bumper" antenna. Not only is the orientation wrong, it crams it extremely low on the vehicle and right next to metal. It would "WORK", but my definition of work and yours may be very different. It MAY play on a very local repeater, but that is it.

    This really is an instance where you are stuck with only a few options. Either come to an agreement with the wife about something outside of the vehicle, or don't. Having tried internal antennas and a variety of low profile, homemade versions, I can safely say that you will be disappointed.

    The other concern with anything in the passenger compartment is RF energy frying on you (the passengers) or some of the electronics. Having some vertical separation between you and the antenna is a great help in lessening the RF exposure.

    If you can come to some reasonable compromise in the marriage, you can look at something like this

    They replace the modern "dome" antenna on many modern vehicles. If your car has a similar dome, you could get one of these. That is about as hidden as you are going to get. Or maybe a glassmount.

    Good luck,
  6. KJ4PLT

    KJ4PLT Ham Member QRZ Page

  7. W8UNX

    W8UNX Ham Member QRZ Page

    The hatch window is completely covered in defroster elements and on-glass antenna for the radio. I hesitate to put any antenna inside the car, anyway.

    The bumpers on the Magnum have quite a bit of vertical dimension. I think I could get the driven leg of the dipole mostly vertical, with the ground leg forced horizontal, depending on where behind the fascia I put it (more towards the grille). Of course, then I'm dealing with proximity to the steel beam/channel that the fascia wraps and, because the car rides so low to start with, I'm virtually on the ground with it.

    I suspect you are right. This wasn't an issue when I had a pickup truck and she never drove it and we took her car everywhere. Heh.

    Rest assured, I have no desire to put an antenna inside the passenger compartment.

    They have some interesting solutions. The Magnum doesn't have any antennas on it at all. If it had the Sirius satellite option, it would have one of those little puck antennas. Maybe I could get away with a Fuba-style (European-style) install. Something to think about.

    I worry that the RF won't couple to the outside element, opting instead to radiate all over the inside of the car. Probably irrational and over-cautious, but there you have it. Thanks for the suggestion, though.

    Maybe the Euro-style sloped antenna is the way to go. I'd have to find someone reliable to drill the car, though. Hrmmm.
  8. K9STH

    K9STH Ham Member QRZ Page

    It is possible to use the rear window as a "slot" antenna. The thing about "slot" antennas is that when the "slot" is wider in the horizontal plane the radiated signal is vertically polarized!

    Glen, K9STH
  9. KJ4PLT

    KJ4PLT Ham Member QRZ Page

    i know several people running the through glass antenna and they claim they work just fine but its like anything else, one persons trash is anothers treasure. if you catch my drift.
  10. W8UNX

    W8UNX Ham Member QRZ Page

    You know, Glen, you might be on to something here. Treating the car as a cavity-backed slot antenna hadn't occurred to me. I wonder how the other windows in the car affect the radiation pattern. I could mount a small probe in the center console arm rest to "drive" the cavity. Hrmmm. :eek:
  11. W8UNX

    W8UNX Ham Member QRZ Page

    I am sure that they do work. Probably better than this behind-the-bumper idea, even. Maybe I will have to reconsider my position.
  12. N0FJP

    N0FJP Ham Member QRZ Page

    I'd say , lets try this....

    Well, I would start out by informing her that the antenna may save her life or the life of someone else that may need help. A cell phone isn'y always an option.

  13. W8UNX

    W8UNX Ham Member QRZ Page

    I just had a brilliant idea. :cool:

    Instead of worrying about hiding an antenna, I'll just explain to my wife that there is a cost associated with achieving both of our objectives. Then I'll ring up the boys at AES-Cleveland and order a VX-8DR and a magmount. :D Or maybe I should do it the other way 'round...easier to beg forgiveness than to ask permission and all that. :eek:
  14. KJ4PLT

    KJ4PLT Ham Member QRZ Page

    there is one problem that can come up. call your dealer and ask what type of tint was used. if its metallic then the through glass antenna wont work.
  15. W8UNX

    W8UNX Ham Member QRZ Page

    I had thought of that. The rear quarter and rear door windows are very dark. I'll have to see if they're passivated or not. Although, the more I think about this VX8R idea.... :cool:
  16. K7DNE

    K7DNE Ham Member QRZ Page

  17. KA9MOT

    KA9MOT Ham Member QRZ Page

    Or you can do the old, "See you never listen to me. We discussed this the other day." Works for her, doesn't it?
  18. K9STH

    K9STH Ham Member QRZ Page


    Then there was the man with 2 black eyes: When asked what happened he said, "I thought she said 'stand up' when she actually said 'shut up'."

    There is absolutely no way of winning an argument with your wife (with any woman for that matter). You may "win" logically, but, you will definitely "lose" otherwise!

    Glen, K9STH
    (who has a wife and 3 daughters)
  19. K8ERV

    K8ERV Ham Member QRZ Page

    There used to be a coupler (trap?) that allowed a CB to feed the car's broadcast antenna along with the regular radio. Maybe something like that could be designed.

    Or possibly the regular antenna could be swtiched to your rig. ??

    TOM K8ERV Montrose Colo
  20. W0IS

    W0IS Ham Member QRZ Page

    If you're worried about RF inside the car, it seems to me that a setup like that will give you a lot of it.

    It seems to me that if you want absolutely nothing visible outside the car, then the best bet for a permanent antenna is going to be 19 inches of conductor on a window. If running it in a straight vertical line is difficult, running it at an angle. If no ground is available at that point, then run a second conductor horizontally. It will be far from ideal, but it will get out.

    A better option would be a temporary antenna, either magnetic, or something you fabricate yourself to clip to a window.
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