FCC Commissioner Ajit Pai says it is time to rewrite rules for AM
Tue Oct 2 10:10:08 EDT 2012
Anyone remember a guy named (IIRC) Lee Hollingsworth (long-since departed)?
Back in the late '40s and '50s he owned what was then WKBS 1520 in Oyster
Bay Long Island. I think it's now WKIT Mineola with somewhat more than the
250W-D WKBS had but it is still a daytimer on 1520. The huge daytime skywave
from what was then WKBW (now WWKB) used to cream the Oyster Bay station's
signal just about everywhere and Hollingsworth thought he had a solution--a
huge power increase, at least during the 1-1/2 hours after sunrise and
before sunset. To avoid interfering with WKBW's groundwave, he proposed a
sky-wave-cancelling antenna which he wanted to construct by running wires
horizontally from the WKBS tower outward to the guy wires. His idea was
that, when driven with signals of the proper phase with respect to the main
carrier, these horizontal wires would act as a skywave-cancelling antenna
that would send its signal straight upward. I don't know whether
Hollingsworth ever installed the horizontal wires and drove them with a
properly phase-shifted version of WKBS's modulated main carrier, but the FCC
was never impressed with the idea and I very much doubt whether the scheme
would have worked if it had ever been built. I hold little hope for skywave
cancellation of this type and I doubt whether the FCC commissioner who is
proposing it understands the practical limitations of what he is suggesting.
Skywave cancellation has, however, been used with very limited success in
the design of a few AM DAs. The idea there is to use towers of different
heights that, therefore, have different vertical radiation patterns. If the
ionosphere would only hold still from one minute to the next (let alone from
one night to the next), it might actually be possible to tailor the vertical
pattern to produce a stable minimum in the direction of a station needing
protection. As I said, however, the ionosphere has never been cooperative
and the results have, AFAIK, never proven to be worth the effort.
Dan Strassberg (email@example.com)
----- Original Message -----
Sent: Tuesday, October 02, 2012 1:00 AM
Subject: Re: FCC Commissioner Ajit Pai says it is time to rewrite rules for
> In a message dated 10/2/2012 12:57:51 A.M. Eastern Daylight Time,
> firstname.lastname@example.org writes:
> So what was the advantage of the antennas that we discussed on LTAR?
> The fact that they were not tall. --about 75' at most.... which can
> easily slip under any towns zoning laws, thereby preventing nimbys from
> a say.
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