All,
When I took a graduate course in antennas, we studied the Beverage. The
lossy ground is what makes it work by tilting the electric field vector
between the wire and ground. That creates an E-field component in the
direction of the Beverage wire. If the ground were perfect, no tilting
occurs and you would have a terminated transmissin line over ground which
will receive nothing.
I agree with your first sentence but not the second. I will have to agree
with Tom.
If you really want to make a Beverage "quiet" then it seems to me that you
would need a ground screen several feet wide beneath the Beverage wire. I
don't think a single wire will do the job. The wire will still see a lot of
the surrounding soil. A single wire would have to be within a few inches of
the Beverage wire to do the job.
Regards,
Hardy, N7RT
At 12:46 PM 8/20/04 -0400, Roger D Johnson wrote:
>Tom Rauch wrote:
>
>> Second, if it did work to crate a low resistance path the
>> effect would only be to make the antenna stop working.
>> Beverages depend on ground losses to function.
>
>I respectfully beg to differ. The original Beverage was developed
>to receive LF and VLF signals via groundwave. The lossy ground
>caused the wave to "tilt" and hence it was able to induce a signal
>into the horizontal Beverage wire. The situation on HF is different
>as the ionosphere supplies the wave tilt in most cases. It might
>actually be an advantage to make the antenna "deaf" to groundwave
>signals in those cases where there is a strong local broadcast
>station.
>
>My understanding of the wire under the beverage was that it stabilizes
>the impedance when the ground conductivity changes (after rain for
>instance). A stable impedance makes for stable nulls.
>
>73, Roger
>
>--
>Remember the USS Liberty (AGTR-5)
>http://ussliberty.org/
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