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Thread: Antenna bandsplit

  1. #1
    jlamanske No Longer Registered

    Default Antenna bandsplit

    MOL says it is 150-162, several dealers say it is 151-162. I've even seen 150.8-162.

    Part number 8505644V02

    Antenna for JEDI and COSMO series radios.

    Anyone know for sure?

    I posted this on RR forums and got very few answers. I have 1 repeater input on 150.775 and the rest are 151-160. The 150.775 is one of our primary channels, and I am tired of using the wideband antenna, due to the extreme length. If it is only rated from 151-162 would it hurt at all to use it on 150.775?


  2. #2
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    Its fine. The -.225 mhz difference wont kill the radio. I have used that same antenna as far low as 144 without any noticable difference.

  3. #3
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    The helical antenna isn't all that much shorter than the wideband one but it is more flexible, somewhat.

  4. #4
    jlamanske No Longer Registered

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    On another note. Has anyone ever dissected the wideband to see how they work? I'm assuming the top narrow portion is the radiator and the bottom is the ground plane if you will?

  5. #5
    aquaray No Longer Registered

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    I wonder if whip antenna on a portable performs better overall with a narrow bandwidth or wide bandwidth?

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    In general a narrow bandwith antenna will outperform a wideband antenna gain-wise when they are approximately the same length, but at a tradeoff for bandwith. When you trade gain for bandwith with wide band you "spread" the energy across a larger spectral area, so you get signal over a wider range of frequencies, but less concentration of energy at any particular frequency.

    The same principle applies to directional vs. omni antennas, or high-gain vs. low gain. In all cases you are "sqeezing" the radiated energy into smaller area, either horizontally (beam) or vertically (high gain antenna) as opposed to an omni or a low-gain antenna which spreads the available energy into a larger area so the concentration at any point is weaker. This is the principle of antenna "gain".

    (If you were referring to "narrow band" or "wideband" signals, then antennas make no difference, the bandwidths involved are small enough compared to the overall antenna bandwidth it doesn't have any effect.)