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Re: [RADIOSHACKDX394] Dish antenna?

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  • David R. Goodson
    Before Aluminum , beer cans were plated steel. I soldered a bunch of these together (about 40 feet long) and put up a vertical antenna. While impressive to
    Message 1 of 6 , Feb 1, 2006
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      Before Aluminum , beer cans were plated steel. I soldered a bunch of
      these together (about 40 feet long) and put up a "vertical" antenna.
      While impressive to look at, my dipole worked much better.

      By the way, any old timers out there remember CQ magazine and the the
      crazy letters written by
      "whatalidie scratchi" ?

      -Dave Goodson WA6IMC

      Earl W. Phillips, Jr. wrote:

      > Time for another dumb question: is it possible to use a dish antenna
      > for SWL with the DX-394?
      >
    • WJB
      Dish antennas work best at a minimum aperture (diameter) of at the very least ten wavemengths across. 30 MHz is about ten meters, so an absolutely minimum
      Message 2 of 6 , Feb 1, 2006
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        Dish antennas work best at a minimum aperture (diameter) of at the very least
        ten wavemengths across. 30 MHz is about ten meters, so an absolutely minimum
        dish would be 300 meters---abaout 300 yards, or nearly 1,000 feet in diameter.

        At 3 MHz a wavelength is about 100 meters, or 3000 yards, or 10,000 feet in
        diameter. Dishes hundreds or even thousanda of wavelengths across work even
        better---higher gain.

        Ok. Now, as crazy as those numbers are, they are easy to make a dish with in
        space, using an inflatable balloon with only a section of it aluminized, and
        the rest left as transparent mylar, or other space-qualified plastic. In fact,
        NASA plans to make just a large aperture dish at some time in the near future
        for radio astronomy well beyond the earth's atmosphere and various ionized
        layers that, as you know, affect radio propagation---often trapping radio
        waves, and not allowing them to escape into deep space. The large aperture
        radio telescope would be positioned a large distance away from the earth in
        a solar orbit a few millions miles ahead of the earth in essentially the same
        orbital track.

        So, you're going to need a much bigger lot, and possibly some govenrnment
        money to get good results on HF with a dish antenna.

        ;-)

        73,
        W1WJB






        > "Earl W. Phillips, Jr." wrote:
        >
        > Time for another dumb question: is it possible to use a dish antenna
        > for SWL with the DX-394?
        >
        > Trim all but the core of this message when replying to keep replies from mushrooming in size.
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