[BC] RF absorption by foliage

[Paul Smith W4KNX]

There sure is a lot of AM RF down that way south of Detroit.  Now that WXYT,
WWJ are down there with whatever 1200 is these days, and 1130 plus a few
others.  Did you know that area is on top of a big dome of salt.  Thats
where all the salt mines are for road salt for the winter.

Paul Smith\
Sarasota, FL
----- Original Message ----- 
From: "Ed Trombley" <ET at Munn-Reese.com>
To: "Broadcast Radio Mailing List" <broadcast at radiolists.net>
Sent: Sunday, October 30, 2005 4:00 PM
Subject: Re: [BC] RF absorption by foliage


>
>
> >There was a station in Denver that the consultant swore was affected by a
> >line of trees less than a mile away. When the trees were in full bloom,
> >the pattern went "out" ... and when they dried up, the pattern "settled."
>
>
> Back when the TVRO thing was a big deal we used to tell clients to plant
> jack pine trees around their dishes to block MCI and AT&T long line
> microwave interference.  There was this microwave tower located at Lacy,
> Michigan that cut a 5 mile wide interference path east and west half way
> between Jackson and Lansing.  Truck & tree spade would plant 6 trees in a
2
> row pattern that made for max pine between LNA and the microwave tower.
It
> worked very good in all seasons.  Building top sites were a different
> problem with a different solution.  Times have changed.  As I travel
around
> the country I sometimes note that the dishes are gone but the trees are
> still there and 70 feet high.
>
> Over the last 12 years I've trained a bunch of guys on the proper art of
AM
> field measurements.  One of the things I've always told then is that
> measuring on the station side of a large tree will give you a higher
> reading and measuring on the side away will give you a lower reading.
Some
> measurement points require acts of desperation.  Digging a hole, then
> throwing the meter in or measuring under the truck or measuring under the
> road in a large drainage tube is considered by most consultants to be foul

> play.  The trainees always had that look like my wing nut was cross
> threaded.  But at some point in the measurement phase they discover by
> accident the tree thing works.  Its hard to beat a spring time Sugar Maple
> with a sap bucket hanging on it for RF bending qualities.  The dry season
> effect is much less.
>
> Up here in certain parts of Michigan as well as some parts of northern
Ohio
> and Indiana big conductivity swings are just a fact of life.  It usually
> happens when the ground is wet from fall rains and freezes for the
> winter.  After the ground is frozen and gets some snow on it the
> conductivities will come down some.  Then the reverse happens in the
spring
> and conductivities spike when the frost melts and ground turns into
> mud.  Ask anybody that takes care of a directional array in Down River
> Detroit.  That area around Flat Rock, MI seem to be the worst.
>
> Also around Flat Rock we have another strange anomaly.  I have seen
> locations in the middle of a clear square mile, can't blame it on wires,
> where the FIM read some number, say 1mV and a second later its 5 mV a
> second later its back to 1 mV.  The meter will bounce fast, not slow, but
> fast between two numbers on one second intervals and do it for hours.  On
> some radial heading it will do this for miles along the radial.  There is
> no click or snap in the audio.  It has something to do with the ground
> conductivities.  Sometimes when near a power line the effect goes
> away.  Its the strangest darn thing.  I figure that up in Detroit
someplace
> there is a steel mill with an arc furnace that has a ground fault and its
> the AC making it way back to the Nuke plant at Monroe.
>
> And for anybody that's interested.  We just got program test on WFDF,
> Detroit's newest 50 kw array.
>
> Ed Trombley
> The well traveled field guy
> Munn-Reese, Inc.
>
>
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