Herb
Salt water is a conductor (but not a very good once compared with copper
)
Like all conductors salt water will exhibit skin effect so radials IN
the water may not be working as well as they should since only the
portion of the radial that is close to the water's surface is doing much
'work'.
On Wed, 2011-07-20 at 13:01 -0400, Herb Schoenbohm wrote:
> Paul, I was trying to suggest that with a good radial ground the
> impedance variation should be less variable due to moisture. On your
> question, it all depends on the soil. Fresh water is an insulator of
> sorts. Depending upon whether your soil is acidic or basic this could
> get better or worse. I had an interesting installation at WIRA in Ft.
> Pierce, FL where the 1/4 wave vertical was out on a pier on the Indian
> River (salt water) with radials in the water and anchored to the river
> bottom. Still as the tide would rise and fall the base current would
> change accordingly. Now if the river were fresh water and the radials
> ran the same way, and since the fresh water is a much lower conductivity
> than the copper wire, a change in tide would have made much less
> difference, IMHO
>
> On 7/20/2011 11:50 AM, BRYON PAUL n0ah VEAL wrote:
> >
> > > From: herbs@vitelcom.net
> > > To: topband@contesting.com
> > > Subject: Re: Topband: water saturated ground effec
> >
> > t
> > Paul,
> > >
> > > What you experienced could be a misleading indication as ground
> > > conductivity with moisture depends a lot on the actual type of soil.
> > > with a vertical that is less than a quarter wave the direct feed
> > > impedance should be very low. YES, THAT IS WHY I NEEDED THE UNUN IN
> > THE FIRST PLACE WHEN I BUILT THE ANTNNA LAST YEAR-
> >
> > On a dry salt lake or high salinity soil the results
> > > with mixing water would be more noticeable but I don't think this is
> > > what you have there. AGREE-
> >
> > My point here is that one of the reasons the FCC requires AM stations to
> > > have a ground system as part of their application is so there is a
> > > constant radiation with a certain power level that will maintain the
> > > radiation pattern and microvolts per meter at a given distance. A good
> > > adequate radial system is supposed to prevent the very phenomenon you
> > > described.
> >
> > HERB, I UNDERSTAND WHAT YOU WROTE, BUT NOT SURE HOW IT APPLIES TO MY
> > SITUATION WHEN THE SWR LAST WENT FROM 1:1 TO 5:1 WHEN I ADDED THE 26
> > RADIALS EXPOSING THE MISMATCH IMPEDANCE THAT THE AMIDON UnUn WAS ABLE
> > TO MATCH THE COAX TO THE ANTENNA- AT THE TIME, USING THE COMBINATION
> > OF THE UnUn, THE ANTENNA IMPEDANCE WAS ESTIMATED TO BE AROUND 20 OHMS-
> > I TESTED EVERYTHING AGAIN THIS MORNING....STILL GETTING A 2.3:1 SWR
> > MATCH WITHOUT THE UnUn, WHEREAS LAST SEASON, I COULD NOT GET THE SWR
> > BELOW 5:1 WHEN I DIRECTLY CONNECTED THE ANTENNA WITHOUT THE UnUn IN
> > LINE.........WITH THE UnUn THIS MORNING, I CAN GET IT FLAT- ARE YOU
> > SAYING THAT A SOAKED SOIL IN MY SITUATION IS WORSE THAN DRY DIRT?
>
>
> A higher loss resistance makes the match appear to be better....but the
> only way you will know is by field strength measurements over time at a
> fixed location. I believe the standard of a good ground at 1000 Khz is
> 186 microvolts at one mile for a kilowatt carrier.
>
>
> Herb, KV4FZ
> >
> > 73!
> >
> > PAUL TI5/N0AH IN ABOUT 27 HOURS!!!!
> > >
> > > Herb Schoenbohm, KV4FZ
> > > >
> > > >
> > > > _______________________________________________
> > > >
> > > _______________________________________________
> > > UR RST IS ... ... ..9 QSB QSB - hw? BK
> >
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
--
73
Brendan EI6IZ
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
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