Folks:
I found a few tools on the net to investigate patterns of AM antennas to see
if I could see correlations with Rick's observations below.
Nothing conclusive yet, but I learned a LOT using The Radio Locater site for
KGO, KFI, and KOMO, mentioned below.
What I did see, clear as day, when looking at the Field Strength contours at
each station along side google Map images of each station TOWER site, and
backing off to a larger scale, was quite interesting. It was awesome to see
how the wiggles and strong field strength vairations correlated very closely
with salt water locations, and shore line patterns relative to the
transmitter sites.
Terrain features that are very far away have awesome effects on the field
strength contours. Particularly iinteresting is looking at KGO contours to
the east of their array, awash in the South San Francisco Bay, and how it
correlates to the shoreline terrain emerging from the salty water. The
larger field strength lobes of the contour map of KGO closely correlates
where the most, or longest water path exists...
This is also where the phasing design between the three towers seems to be
designed to optimize.
Also, on the KFI, maps it was stunning to see the bulge in the equi
potential line exactly corresponding to the location of the Salton Sea,
which seemed to give a boost of dbs or more on a radial from the antenna
and the Salton Sea.
The KOMO-Seattle station which the Swedish ham says he can hear, has an
enormous spike in the Field Strength Contour map to the north...right where
the salt water is relative to the antenna array.
A long time ago, VOA shut down their Dixon site near Davis CA. It was
situated in the California Delta with a lot of salty or brackish water ways
amongst its antennas. I wonder if the site was selected because it was
cheap, or because of all the salty wet water-mud that was around.
Man, that SALTY water sure DOES create some SWEET spots.
KGO:
http://www.fccinfo.com/CMDProEngine.php?sCurrentService=AM&tabSearchType=Appl&sAppIDNumber=249372&sHours=U
http://doc-weblogs.com/2004/09/30
http://radio-locator.com/
http://radio-locator.com/cgi-bin/pat?call=KGO&service=AM&status=L&hours=D
http://radio-locator.com/cgi-bin/page?p=maps
http://radio-locator.com/cgi-bin/finder?call=KGO&x=10&y=8&sr=Y&s=C
KGO Google Maps
http://maps.google.com/maps?f=q&hl=en&geocode=&q=Fremont+CA&ie=UTF8&ll=37.544169,-122.10248&spn=0.044575,0.080338&t=h&z=14&iwloc=addr&om=1
KFI:
Antenna Pattern:
http://radio-locator.com/cgi-bin/pat?call=KFI&service=AM&status=L&hours=U
KFI Google Map:
http://maps.google.com/maps?f=q&hl=en&geocode=&q=+++%0933%C2%B0+52'+47%22+N,++118%C2%B0+00'+47%22+W&ie=UTF8&ll=33.877827,-117.949219&spn=5.362058,8.942871&t=k&z=7&om=0
KOMO Seattle:
Antenna Pattern
http://radio-locator.com/cgi-bin/pat?call=KOMO&service=AM&status=L&hours=D
KOMO Google Map Image:
http://maps.google.com/maps?f=q&hl=en&q=47.46361,+-122.44083+(KOMO-AM)&om=1&ie=UTF8&ll=47.463564,-122.442005&spn=0.008109,0.017467&t=h&z=16
Sincerely, Pat Barthelow aa6eg@hotmail.com
http://www.jamesburgdish.org
Jamesburg Earth Station Moon Bounce Team
http://www.cq-vhf.com
>From: "Rick Karlquist" <richard@karlquist.com>
>Reply-To: richard@karlquist.com
>To: K6TFZ@aol.com
>CC: towertalk@contesting.com
>Subject: Re: [TowerTalk] Sweet spot locations
>Date: Fri, 3 Aug 2007 13:32:37 -0700 (PDT)
>
>K6TFZ@aol.com wrote:
> > In one of the pictures I noticed a lightning transformer.
> > I could not easily find a description via Google of how
> > this operates. I would appreciate it if someone would
> > point me in the correct direction for an explanation.
> > Thank you. Geoff, K6TFZ
> >
> > (Now I know why KGO is like a local station down here
> > in L.A. during night hours. They can sometimes be
> > heard during daylight hours in QRM-free areas.)
>
>KFI in Los Angeles can be heard during daylight in
>the SF bay area near the coast. KOMO in Seattle is
>stronger in the SF bay area than KGO is in the Seattle
>area. Also, KFI comes into Seattle about as well as
>KGO. KGO's apparent dream location, in my experience,
>has not translated into demonstrably better performance
>than other AM stations.
>
>Rick N6RK
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