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Thread: PS mic W/stubby ant or antenna extension and wideband antenna?

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    Default PS mic W/stubby ant or antenna extension and wideband antenna?

    VHF operation. Here's the gig.

    Wearing a load bearing system, with radio at waist level. MOSTLY concealed although not always and using 2 wire surveillance earpiece or commander II mic.

    Have options of running a public safety mic with a stubby, OR, running a 1' extension cable, and running the wideband antenna on the back strap that goes over the shoulder, still vertically polarized, similar to PRC setup.

    The wideband antenna on the speaker mic, while funny, is not practical. Hell, I'm getting it off the belt because it snags on everything, pokes me in the armpits, etc etc.



    Wideband on straps

    Pros
    • More efficient radiator across band
    • Less visible when needed


    Cons
    • Possible groundplane/capacitive coupling issue
    • Highly directional to the rear
    • Have to move the body to get better reception in fringe areas




    Stubby on PS mic

    Pros

    • Farther away from body, less directional
    • Can remove spkr/mic and move antenna for higher elevation/clearer LOS

    Cons

    • Poor radiation pattern
    • -6db from wideband antenna
    • Can't use commander mic






    Or, possibly, another type of antenna? Maybe a 1/2 wave?

    Thoughts? Suggestions? Anything I'm overlooking?
    Last edited by Technoweenie; May 05, 2013 at 10:42 AM.


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    Nothing? No one has input?

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    Apart from the 800 MHz dipole all quarter waves and helicals need a ground plane which the radio and your capacitively coupled hand provides. PS mics only work with certain antennas and in my view only work adequately at UHF/800MHz.

    As you appreciate if you want decent operation in fringe areas you have to have the antenna clear of your body and shoulder height holsters while not low profile are the best way to go.

    Have a look at this interesting trial done by some fiery types posted on Batlabs by FireCpt809:

    http://api.ning.com/files/YhwQqZhqiB...se_FINAL_2.pdf
    Last edited by Astro Spectra; May 07, 2013 at 11:20 AM.
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    VHF on the top of a public safety mic is not recommended by mother /\/\oto. I would agree that there is not enough of a ground plane to counterpoise the antenna.

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    Quote Originally Posted by gsxxr1300r View Post
    VHF on the top of a public safety mic is not recommended by mother /\/\oto. I would agree that there is not enough of a ground plane to counterpoise the antenna.
    There are numerous PD's in my area that do the PS mic with a VHF stubby antenna in my area. They seem to love it and it works for them. They are using a multi site voted system with at least 2 repeaters on watertowers.

    The link provided by Astro spectra was sent to me by a member of the comittee that did the research. I usually carry my XTS5000 on the FDNY strap if I am on the engine or on a belt clip and no mic if I am on the Medic and take it off my belt if I need it.

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    We have an agency around me that uses Jedi's (mostly HT1000 and a few MT2000) for their officers with the NMN6228/6244's with a Visar antenna and have used this setup for years. No failures of the radios, and they work better than trying to talk off a standard heliflex off their belt with a standard RSM. Their repeater system is comprised of MTR2000's with single TX site and 5 remote receivers with a voter.

    The factory Jedi VHF "stubby" appears to be a Centurion (I have several) and have never had any problems using them on my Jedi radios or the public safety RSM, except I do notice the antenna itself gets warm after extended keydowns! Nice dummy load they are.

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    OK, so what about capacitive coupling/absorbed radiation issues with a back/strap mounted whip antenna, ala MBITR ?

    I could easily make a dipole from coax and follow the straps on the back for framing/support.

    Or just use the factory wideband antenna with a short coax extension (already built the cable )

    My concern is which will be better, short of making a manpack.

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    Quote Originally Posted by Technoweenie View Post
    OK, so what about capacitive coupling/absorbed radiation issues with a back/strap mounted whip antenna, ala MBITR ?

    I could easily make a dipole from coax and follow the straps on the back for framing/support.

    Or just use the factory wideband antenna with a short coax extension (already built the cable )

    My concern is which will be better, short of making a manpack.
    Screw all that. Just do what I did when I was 15:

    - Pick up "power pack" from Wal Mart (12VDC)
    - Make cigarette lighter adapter for your mobile radio
    - Put power pack, and mobile into backpack
    - Bring 5/8wave magmount and partially zip it up in the same backpack, with whip sticking out the top
    - Run 30-40W 2" from your head and drive around on your bike
    - Disregard everyone who calls you a ******

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    Quote Originally Posted by Mars View Post
    Screw all that. Just do what I did when I was 15:

    - Pick up "power pack" from Wal Mart (12VDC)
    - Make cigarette lighter adapter for your mobile radio
    - Put power pack, and mobile into backpack
    - Bring 5/8wave magmount and partially zip it up in the same backpack, with whip sticking out the top
    - Run 30-40W 2" from your head and drive around on your bike
    - Disregard everyone who calls you a ******
    Or just show up at the Dayton Hamfest where everybody will call you "cool" and hope somebody snaps a picture and posts it to Hamsexy.com. Hopefully though, you have left your pink socks and the ARES orange vest in the car......

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    Yeah, not going the hamsexy route, sorry.

    99% of the time, I'm wearing a shirt OVER this rig, so I can't get a 5/8 wave and rock it like a manpack.

    Here's what I'm talking about. Extension in red, wideband whip (standard /\/\ VHF) in grey/black. The black Xs on the strap are tactical nylon restraints.

    Last edited by Technoweenie; May 08, 2013 at 09:59 PM.

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    There's a company that makes something precisely like this that's designed to be attached to PALS webbing. Not super expensive either.

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    Basically an extension and a piece of velcro fabric. I guess it'll work OK if it's tacti-cool enough for a tier 1 operator to use. Seriously though, we're still talking about a 30db null to the front (through a body) and probably a 6db drop because of closeness to body, or something like that?