[BC] KDKA's 0.5 mV/m 50% skywave coverage

[Dan Strassberg]

Dana wrote that KDKA's 50% skywave extends 750 miles.

Nope! Not only does the protected skywave service of all North American
Class A AMs terminate at the national border, the rules for calculating the
nighttime service areas have changed. 50 kW ND from an (~200 degree) antenna
that produces a groundwave of ~400 mV/m/kW @ 1 km (which is typical for
Class As) no longer produces a 0.5 mV/m 50% skywave coverage radius of 750
miles. (Never mind what you can hear on your radio; as I pointed out in an
earlier posting, which Dana quoted, listening is not only irrelevant; it is
dangerous, subversive, and probably punishable by death ;>) I don't have the
exact distance figures for KDKA, but WSCR's skywave service now extends only
to around Buffalo NY--a distance of approximately 450 miles and WSB's
extends only to around Baltimore, which may be a little bit more than 450
miles, but not much. In other words, a few years back, with the stroke of a
pen, the FCC reduced the nighttime service areas of US Class A stations by
approximately 64%. WBZ's nighttime signal in Chicago and Milwaukee is
legendary. Nevertheless there is now a full-time Class D AM in the Chicago
suburb of Vernon Hills. Yeah, WNVR's nighttime power is low and the signal
is directional to the west, but the station is located in an area where WBZ
delivers a signal of at least 2-3 mV/m on most nights.

--
Dan Strassberg, dan.strassberg at att.net
eFax 707-215-6367