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AM RADIO PATTERNS
- Thread starter OldChicago
- Start date
...for whatever it's worth, when I worked at the then-WRJR/1500 in Zion, we were a daytimer that had to throw our signal to the south to protect KSTP/1500 St. Paul. Consequently, we found we had a sizeable pocket of listeners in Evanston and Skokie (bigger than the listener feedback we ever got from Kenosha County, in fact)...
The WJJG towers look like two way/dispatch towers. They are self supporting and not painted or lighted. I drove past them at least a few times before noticing that they seemed to look like an array. I had a tower tour every time I drove from SE Michigan to Chicago or Milwaukee. I saw WITL (now gone), WJIM, WBCK, WKLZ/WQLR, WHFB, WIMS, WLTH, WIND, WBGX, old WMVP array, old WTAQ, WRDZ, old WAIT, WJJD/WYLL, WEAW/WKTA, WEEF, and WSBC/WXRT and night WNTD depending on the route.
I was actually riding in the car going by the WJJG array. I would not have been able to crane my neck and see the WIMS, WCFL/WMVP old, huge footprint self supporters and WTAQ's old four tower array otherwise. WIND, WRDZ, WBEE/WBGX, and WJJD/WYLL would be hard to miss. WEAW/WKTA's are obscured by trees as I recall. WLTH would not necessarily strike you as an AM tower right away. I also had the best radio with a signal strength meter I ever had, with a good logarithmic response. WITL was hard to miss, but the intercahnge ramp was in a deep null, and another nearly identical array that they abandoned stood for years a couple miles away, with just as strong a signal while going by. I found several arrays with that radio, before the locations were widely available on the internet. WLTH signal was strong, I looked and saw the tower next to the railroad track.
My experience is that M-3 is inaccurate in many areas, and that the Great Lakes are better than many 8 areas on land. Canada shows 10 on their sides of the same lakes.
Because of the skin effect, only the ground right near the surface matters.
ai4i said:
There's so much going on, it's often hard to say. I saw the greatest increase over a 40 mile path, 4 times the summer field strengths, when it was just -15 degrees F. As I recall, it was dry. It was 1992. I'd have to look up the history. The snow and ice seem to make more difference when they fall on sand and rocky soil, so that sounds right.
If the snow and ice have the same conductivity, it would make no difference. And the actual ambient temperature would also affect it. In the situation mentioned before, as the ambient temperature increased rapidly to +15 F, you could almost watch the field strength meter decrease as it warmed up. The engineer from WMTR in New Jersey wrote an article about great diurnal field strength variations with temperature about 35 years ago. He measured a two or three fold difference in WABC during the same day.
Boring subject 
radioaircheck said:Boring subject
Nobody is making you read this tread.
ai4i said:
What states have all nondirectional stations? Alaska and Hawaii? I don't think the conductivity maps are that accurate there either.
ai4i said:
KAIM (Now KHCM) moved, IIRC, from 870 to 880. It was directional from Moloda'i aimed at Oahu with 50 kw, but with power so expensive in Hawaii, the abandoned that idea. And then, to allow modification of co-owned 870 in Glendale / LA, they moved it up the dial.
There are 3 AM's in Peoria, IL. 1290 & 1350 have crazy nitetime patterns where you can get their signal south to Springfield but can't get their signal 20 miles east. Who are they protecting with those patterns on those non-clear channel frequencies? Guess the FCC has their reasons. Anybody care to comment?
howardm said:
1290 has a deep null protecting WHIO in Dayton. I believe 1350's null protects Kokomo and Akron. That's the nature of the "regional" (former class III) channels, and it's why the 1290 and 1350 (and 1470) sites are all in such close proximity - most of what they're protecting is east and a little south of Peoria, so the transmitter sites are also south and east.
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