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7745Re: [BCD396XT] Antenna Options for my BCD396XT

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  • Tony Langdon
    May 1, 2013
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      On 2/05/13 7:30 AM, Preston Ward wrote:
      > I'm looking to get a wideband omnidirectional base antenna too. I'm going to put it 30-35' up. Anyway, I'm considering 4 models... does anyone have any opinions on which one of these might be better?:
      Normally I'd say one of the better discones, unless your interests are
      limited to a specific band. I can comment on your suggestions, as I
      don't know those antennas.
      >
      > Ideally, I'd like to be able to pick up one city 75 miles away, but I still want to go with an omnidirectional at least for now.
      Unless you're on a decent hill or mountain, your goals may be in
      conflict. There is generally a tradeoff between gain, bandwidth (as
      whether it covers a single band or is wideband) and directionality.
      You're demanding at least 2 of those, if not all 3.

      The most likely antenna to get those signals from 75 miles away is a
      directional antenna cut for a specific band. This focuses the signals
      from one direction, and utilises all of the elements to contribute to
      the gain.

      Omnidirectional antennas have to try to form a radiation pattern that
      looks like a pancake, which means it focuses all of its attention on the
      horizon. But even then, that volume of space is larger than the
      directional case above, so the maximum possible gain is lower.

      Finally, a lot of broadband antennas don't use all of their radiating
      elements on any given frequency, so these have even less ability to
      focus the signals. However, that is compensated for by their extremely
      wide bandwidth. You can get directional wideband antennas (e.g. a log
      periodic), but their gain is a lot less than a Yagi or other narrowband
      antenna cut for a specific frequency in the range covered.

      It may be that you either have to install 2 antennas and switch between
      them, or run 2 scanners (maybe one of them can be a cheap scanner).

      Or move to a mountain midway between your target areas! ;)

      --
      73 de Tony VK3JED
      http://vkradio.com
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