Re: [IRCA] Max. Groundwave Propagation Distance?

["Paul B. Walker, Jr." <walkerbroadcasting@xxxxxxxxx>]

I beleive the 580 you're referring to is 5KW Day/34W Night, Non Directional
Facility WKSK West Jefferson, NC not far from the TN/VA state line.

Paul



On Sat, Mar 8, 2008 at 3:05 AM, George Sherman <georgesmn@xxxxxxxxx> wrote:

> CBK (about 70 mi N of Regina) is surrounded by great ground & I seem to
> recall them claiming to get improved results from having double the normal
> number of ground radials? Anyway, they go 700 miles for sure on groundwave
> weakly, on a good radio. Summer reception near Park Rapids, NW MN, on a
> portable.
>
>  That 100 mi or so limit for *average* ground may be true?
>
>  WLW can be heard weakly days in SE MN, about 650 miles. Cleveland on 1100
> put a weak carrier into MN & NE daytimes, many years ago. We had a car radio
> that could get summertime mid-day reception of some Chicago stations in
> Northeastern SD, about 550 miles. WCCO is one of the strongest signals in
> parts of Eastern SD during the day 200+mi.
>
>  WNAX-570 SD day primary almost reaches Minneapolis, about 200 miles.
> Omaha on 590 very readable, almost 300 mi, on SRF-59 barefoot. Several
> Kansas City stations weakly days, almost 450 miles, with loop.
>
>  As we go up the dial WHO-1040 easily readable @ 225 miles. KXEL-1540 also
> @ 175mi.
>
>  Local KYMN-1080 on the 11 watts night, has a good groundwave strength at
> 25 miles, but some QRM most nights.
>
>  But I've been in W NC where a station on 580 had a day primary of 15-20
> miles, and a 7 mile distant graveyarder could not be detected in the mess at
> night. 73, George S., MN
>
> Nick Hall-Patch <nhp@xxxxxxxx> wrote:
>  At 01:52 AM 3/8/2008, you wrote:
> >My best distance midday reception, was KORL-650-10KW-Honolulu, HI (2500
> >miles over water) heard around 1970. KORL was mixing with KYAK-Anchorage
> >(1800 miles also over water). That would be nil to impossible today with
> >CISL there. No Sacramento CA on 650 then either. I also heard several
> >Midwesterns (WMAQ,WGN, WBBM, WLS, WHO, etc) around 1 PM Pacific time
> >back in the early 70s too. In those days I had a 600 foot longwire
> >running N/S.
> > In recent years around 2000 I logged
> >around 2PM or so in mid winter, KATQ-Plentywood MT, KFTI-Wichita KS, an
> >Houston TX. So long haul Midday Winter DX can be had.
>
>
> I guess the problem is determining what is ground wave and what is skywave
> especially during a winter day in the northern part of the USA, or any part
> of Canada. If there's any amount of fading over less than a few minutes,
> it's generally thought that there's a skywave component.
>
> There's several scientific publications that I've seen that address MF
> groundwave from a theoretical standpoint;one (NTIA Report 99-368: Medium
> Frequency Propagation Prediction Techniques and Antenna Modeling for
> Intelligent Transportation Systems (ITS) Broadcast Applications by Nicholas
> DeMinco, available at http://www.its.bldrdoc.gov/pub/ntia-rpt/99-368/)
> says "At 0.5 MHz over average ground, the ground wave predominates over
> the sky wave from the transmitter site out to distances of about 150 km,
> where
> the two signals are equal. The signals add as vectors, and destructive and
> constructive interference
> can occur. At distances beyond 150 km the sky wave is the predominant
> signal. At a signal
> frequency of 1.5 MHz, the distance where the two signals are equal reduces
> to 45 km, because of the
> increased loss at the higher frequency."
>
> Given the above figures, I'm not sure how I received CBK-540 here in
> Victoria at 2PM local on a mid-July afternoon (1PM sun time, given it was
> daylight saving time then); I wouldn't have expected much skywave then.
>
> The references in the above publication will give you a wealth of sources,
> some of them stiff with mathematics.
>
> Other publications
> http://www.its.bldrdoc.gov/pub/ntia-rpt/86-203/index.php
>
> http://downloads.bbc.co.uk/rd/pubs/reports/1978-07.pdf
>
> The FCC's AM groundwave field strength graphs:
> http://www.fcc.gov/mb/audio/73184/index.html
>
>
> Gordon Nelson's article, "Skywave or Groundwave Reception", National Radio
> Club reprint P9 (http://www.nrcdxas.org/) addressed the problem of
> identifying which is which for the DXer, and was an initial introduction to
> long haul groundwave propagation for me.
>
> Hope this helps.
>
> best wishes,
>
> Nick
>
>
>
> *****************************
> Nick Hall-Patch
> Victoria, BC
> Canada
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-- 
Sincerely,
Paul B. Walker, Jr.
www.walkerbroadcasting.com
www.myspace.com/walkerbroadcasting
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