[TowerTalk] Sweet spot locations

[Pat Barthelow]

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 at hotmail.com
http://www.jamesburgdish.org
Jamesburg Earth Station  Moon Bounce Team
http://www.cq-vhf.com

>From: "Rick Karlquist" <richard at karlquist.com>
>Reply-To: richard at karlquist.com
>To: K6TFZ at aol.com
>CC: towertalk at contesting.com
>Subject: Re: [TowerTalk] Sweet spot locations
>Date: Fri, 3 Aug 2007 13:32:37 -0700 (PDT)
>
>K6TFZ at 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