I wonder if the sweet spot/sour spot locations are due to local land
conditions, or are simply areas of multipath cancellation, caused by
interaction of ground wave, and sky wave components, from a given station.
Another Antenna Tower that I had the great fortune to be given a tour of,
was WSM, in Tennessee. An unforgettable visit and tour by then (1990) Chief
Engr Everett Lawson (SK).
A very distinctive tower, made by Blaw-Knox, one of a handful around the
country, from the 30's era.
http://hawkins.pair.com/blaw-knox.html
They purposely built a 5/8 wavelength radiator design in order to suppress
higher lobe radiation causing selective fading at a particular radius from
the antenna. The big bulge in the middle of the tower apparently clouded
their efforts, and they tweaked the total height to get the best, no fade
reception at important distances.
Check out WSM on the web:
http://www.fybush.com/site-020424.html (and other locations)
You gotta see the tower base insulator...a Lapis Ceramic pair supporting
tons and tons of weight.
So, on the sour spots, are they specific to a single location and station?
Or, at a given location are many, (most?) stations noticeably weaker?
Selective Fading?
Sincerely, Pat Barthelow aa6eg@hotmail.com
http://www.jamesburgdish.org
Jamesburg Earth Station Moon Bounce Team
http://www.cq-vhf.com
>From: Jim Rhodes <k0xu@iowadsl.net>
>To: towertalk@contesting.com
>Subject: Re: [TowerTalk] Sweet spot locations:
>Date: Sat, 28 Jul 2007 22:36:01 -0500
>
>Not just sweet spots, but "sour" ones also. I remember a few from my
>teenage years, driving around with the AM radio and certain spots the
>radio would just go dead consistently. Had not been back there for
>about 40 years before driving through the area a while back. Just to
>check it out I switched the car radio on to an AM station before we
>reached that section of highway and sure enough, it still dies there.
>Couldn't see anything around that should cause it, but whatever it is
>it is still there.
>
>At 08:20 AM 7/28/2007, Barry Kirkwood wrote:
> >Years back I recall a note in Technical Topics in RSGB Radio
>Communications
> >to the effect that experience of the British Post Office (which once had
> >monopoly of telecommuncations in the British Isles ) was that coastal
> >stations had something like 20dB advantage over inland stations on HF.
>May
> >not have the details precise, but it was to that effect.
> >Whatever, as one of those older folk, back in the days when there was no
>FM
> >broadcasting, I well remember "sweet spots" when listening to the AM MF
> >broadcast band on the car radio while travelling, especially by
> >night.Notjust skip distance, as effect was noticed on stations at
> >different distances
> >And not necessarily by the seaside. Other folk noted the same thing.
>This
> >was in ZL, but certainly noticed the same effect in North America in
>1980.
> >Any thoughts on this?
> >73
> >Barry ZL1DD
> >
> >--
> >Barry Kirkwood PhD ZL1DD
> >barrykirkwood@gmail.com
> >_______________________________________________
> >
> >
> >
> >_______________________________________________
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> >TowerTalk@contesting.com
> >http://lists.contesting.com/mailman/listinfo/towertalk
>
>Jim Rhodes K0XU
>jim@rhodesend.net
>
>Experience is the thing you have left when everything else is gone.
>_______________________________________________
>
>
>
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