Herb,
My only response is to suppose that the layer or "normal" dirt you have, the
former hay field is in fact acting as it should without or with very little
influence from the brackish water table below. Physics can't be changed, so
that is the obvious answer to me.
Likewise, at VP6DX in February 2008, we were very surprised at the fabulous
performance of the Beverage antennas over the coral with the terminations
within 50' of the ocean at either end. There was enough soil (perhaps
ranging from 2'-3') to support the growth of the Tournefortia Argenta trees.
I am supposing that this shallow layer of soil, coupled with the coral
below, was enough separation from the salt water to allow the Beverage
conductor to "see" the closer, less conductive earth rather than the higly
conductive water table influence somewhat deeper below the surface.
At XZ0A the Beverages were single wire, terminated variety.
At VP6DX all Beverages were two wire, reversible variety. Each of the two
wires is referencing ground, as they are in fact two separate antennas.
Each antenna (wire in the twin lead) performs by itself with no influence on
the other with regards the other half of the "transmission line"
configuration.
I believe your hay field and our Tournefortia Argenta "jungle" are very
similar environments for the depoyment of Beverage antennas.
Have a great day.
Milt, N5IA
----- Original Message -----
From: "Herb Schoenbohm" <herbs@vitelcom.net>
To: "Milt, N5IA" <n5ia@zia-connection.com>
Cc: "Nick Hall-Patch" <nhp@ieee.org>; <topband@contesting.com>
Sent: Thursday, June 24, 2010 3:56 AM
Subject: Re: Topband: K3NA Loop Array
> Very interesting especially since all my Beverages are directly adjacent
> to a huge Salt Pond some terminating about 500 feet away. Under each
> Beverage the water table (of brackish water) is only about 10 feet down
> but the soil above is fair to good being part of a former hay field
> covered will tan tan bushes, weeds, and some form of cactus plants. The
> two wire Beverages ar a mixed bag of DXE ladder line and WD-1A KD9SV
> boxes.They work very well with an awesome F/B and good directivity tested
> constantly on upper segement BC stations. They even work extremely well
> up to and including 10Mhz.
>
> My question is dos the fact that my Beverages are two wire reversibles
> make any difference in relationship to the ground below or is the return
> path of the second wire phased out of the equation?
>
> Thanks,
>
> Herb, KV4FZ
>
>
>
> Milt, N5IA wrote:
>> In the most simple explanation of the theory of operation of the
>> Beverage antenna you must understand that the single wire above (or on)
>> the ground is 1/2 of an unbalanced transmission line. The earth
>> conductivity is the other "wire" in the transmission line.
>>
>> When the earth 1/2 of the "transmission line" becomes very conductive,
>> the whole array approaches being an actual 2-wire transmission line
>> (perfectly balanced). When that happens there is near ZERO signal
>> received.
>>
>> The more unbalanced the line is, the more signal level is impressed on
>> the wire which can be detected by proper impedance matching to a coaxial
>> feedline going to your receiver. That is why the Beverage works well
>> over poor earth.
>>
>> I have posted this before, but it bears repeating the practical
>> experience.
>>
>> At XZ0A on Thahtay Khun Island in January, 2000, the Beverages installed
>> over land on the island worked very well. They worked so well that
>> electrical noise from the mailand, more than 5 miles distant in the
>> direction of JA, was preventing us from hearing well the bedspring ops.
>>
>> I constructed a Beverage oriented in the JA direction, in a secluded
>> location which would isolate the view of the mainland. The intent was to
>> be able to hear the weak JA signals without the electrical noise from the
>> mainland.
>>
>> The only place this could be done was right at shore level on the west
>> side of the island. A good portion of the antenna had to be over the sea
>> water, in particular at high tide. Suffice it to say, the antenna heard
>> NOTHING!!!! It was essentially a 2-wire transmission line terminated in
>> its characteristic impedance; that is, a dummy load.
>>
>> This post is not meant to be a treatise on Beverage antenna theory.
>> Hopefully the simple explanation of how and why its works over poor
>> earth, and conversely why it DOESN'T work over high conductivity soil or
>> water, will be of use to some out there in radio land.
>>
>> GN de Milt, N5IA
>>
>> ----- Original Message -----
>> From: "Nick Hall-Patch" <nhp@ieee.org>
>> To: <topband@contesting.com>
>> Sent: Wednesday, June 23, 2010 12:16 PM
>> Subject: Re: Topband: K3NA Loop Array
>>
>>
>>
>>> Consider me to also not be an expert either in Beverage antenna theory,
>>> or in
>>> wave propagation. I wonder however whether some of the idea that the
>>> Beverage
>>> works best over poor ground dates back to the original development of
>>> the
>>> antenna, when it was used for low frequencies that were propagated by
>>> ground
>>> wave that had no horizontal component to the wavefront. This would not
>>> produce
>>> much signal on a Beverage antenna that is dependent upon that horizontal
>>> component, unless the wavefront was passing over a poor ground that
>>> would cause
>>> it to tilt, introducing a horizontal component.
>>>
>>> Most of us use Beverage antennas for DXing on medium frequencies, and
>>> the
>>> signals we receive are skywave. Even if the original wavefront had no
>>> horizontal component, by the time the ionosphere has finished with it,
>>> and
>>> delivered it to our receiver, there may be quite a reasonable horizontal
>>> component to it. One would expect that a Beverage antenna should
>>> therefore be
>>> able to generate a signal, even with quite a good ground underneath.
>>>
>>> Standing by for corrections to my perception...
>>>
>>> 73,
>>>
>>> Nick
>>> VE7DXR
>>>
>>> Quoting rfoxwor1@tampabay.rr.com:
>>>
>>>
>>>> ---- Greg - ZL3IX <zl3ix@inet.net.nz> wrote:
>>>>
>>>>> Hi Eric,
>>>>>
>>>>> I am interested in a statement in your paper, "Beverages don't work
>>>>> over
>>>>> high(ly) conductive earth"
>>>>>
>>>>>
>>>> This may be very simplified. I am far from a Beverage expert, but it
>>>> was
>>>> explained to me once that the Bev works well over poorly conducting
>>>> soil because the wavefront is no longer just vertically oriented, as it
>>>> travels down the length of the antenna wire; but rather is retarded,
>>>> causing a forward tilt in the wavefront. This forward tilt then will
>>>> induce a RF current down the length of the wire, which sums up at the
>>>> end (where the RX is). IOW instead of just a vertical field, there is
>>>> both a vertical and a smaller horizontal field, and the poorer the
>>>> soil,
>>>> the greater horizontal field induces the antenna current you need.
>>>> -Bob k2euh
>>>>
>>>>
>>> --
>>> Nick Hall-Patch
>>> Victoria, BC
>>> Canada
>>>
>>> _______________________________________________
>>> UR RST IS ... ... ..9 QSB QSB - hw? BK
>>
>> _______________________________________________
>> UR RST IS ... ... ..9 QSB QSB - hw? BK
>>
>>
>
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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