Re: [IRCA] KOFI-1180 Coverage map for advertisers:

[Glenn Hauser <wghauser@xxxxxxxxx>]

Click on Advertise, at http://www.kofiradio.com/indexk2.html

The four different contours are not labeled! What does this mean? Why in the
world aren`t they labeled with night/day, mv/m? KOFI is 50/10 kW U2, which
means 50 kW day, non-direxional, and 10 kW night, direxional.

The smaller non-circular contour, however looks like it is groundwave,
influenced by the mountain range to the west, so that would be daytime? The
larger circular contours sure don`t go very much further as would be expected
for nighttime skywave, but that is supposed to be direxional. KOFI is one of
those few ``almost clear channel`` stations which ought to have big coverage at
night, even if direxional, not the smaller inside contours (that is, until
IBOCh interference from KEX-1190 Portland et al. messed everything up).

On the contrary, the bigger circular patterns must be theoretical daytime
coverage, so the smaller non-circular contours must be nighttime, even if they
don`t match FCC or radio-locater versions. Has anyone axually measured their
field strength in different direxions and at different distances? Otherwise,
this is all pretty meaningless (except to advertisers who don`t know any
better?)

The NRC Pattern Book shows a very different picture. Daytime is a
non-direxional circle, and nighttime is almost a figure 8 N/S, with a null
toward WHAM Rochester, of course. Almost, meaning the null to the west is not
pulled in nearly as much as to the east. This matches the night pattern at FCC:
http://www.fcc.gov/ftp/Bureaus/MB/Databases/AM_DA_patterns/45972-10705.pdf
And it`s dated 16 Sept 2007 --- does that mean there has been a very recent
change?? Transmitter site is just east of Kalispell, which is a good idea since
there must be a night null to the east.

Of course, the circular daytime pattern merely means it starts out
non-direxional, not taking into account mountain blockage, differences in
ground conductivity.

What do the patterns at radio-locator.com show? Still different! Daytime: 
http://www.radio-locator.com/cgi-bin/pat?call=KOFI&service=AM&status=L&hours=D
has it circular but cut off toward the north, i.e.  Glacier NP region, not
west/southwest, the more distant Bitteroot Range.
Nighttime: 
http://www.radio-locator.com/cgi-bin/pat?call=KOFI&service=AM&status=L&hours=N
is similar to the others, kidney-shaped N/S with null toward east. This of
course is groundwave at night, ignoring skywave! 73, Glenn Hauser, Enid OK


       
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