Limbaugh returns to WRKO

Laurence Glavin
Tue Aug 7 13:41:12 EDT 2012

>----- Original Message -----
>From: Scott Fybush
>Sent: 08/07/12 11:06 AM
>Subject: Re: Limbaugh returns to WRKO

 >On 8/7/2012 3:52 AM, Bob Nelson wrote: > I stand corrected about Entercom's other AM in Buffalo. And the 1520 > they have, WWKB, actually can sometimes reach our own area (even if it > can't reach Rochester for some reason). >It's not "for some reason." It's for a very easily explained engineering >reason. Any AM antenna system sends signal outward along two paths: a >groundwave signal that travels along the ground for as far as the ground >conductivity can carry it, and a skywave signal that shoots upward at an >angle. During the day, the skywave signal passes through the ionosphere >and out into space. At night, charged layers of the ionosphere reflect >those skywave signals back down to earth at a distance. >Most of the time, those skywave bounces land at a distance beyond the >end of the normal groundwave coverage. But on a fairly high MW frequency >like 1520, from relatively short towers, the first skywave bounce lands >quite close in - 75 miles in, or thereabouts, which puts it right over >Rochester. And that's close enough that there's still a lot of >groundwave signal present. Because the two signals arrive over different >paths, they land out of phase, and it's that phase cancellation that >makes 1520 hard to hear after dark in Rochester, just as it makes 1030 >hard to hear sometimes around Springfield, or WGY around Syracuse. >It's not so much that WWKB "can't reach Rochester" - it's more that it >reaches Rochester by too many different paths at once! >s 

 On a few occasions, usually late at night in the fall/winter period of long hours of darkness, I've experienced that
 short-wave effect while listening to WBZ-AM, whose antenna system is the most distant Boston-area AM
 signal I receive reliably at night. I live 30 miles due north of Boston within easy walking distance of the NH border,
 so the intervening mileage the signal traverses can't be much more than forty miles.

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