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From: roy@alanine.phri.nyu.edu (Roy Smith)
Newsgroups: sci.electronics
Subject: Commercial radio transmitters
Message-ID: <1990Dec20.172920.7325@phri.nyu.edu>
Date: 20 Dec 90 17:29:20 GMT
Sender: news@phri.nyu.edu (News System)
Organization: Public Health Research Institute, New York City
Lines: 25


	In New York, two radio stations (I think it's WCBS and WNBC, both
50 kW AM stations) transmit from the same tower.  How do they do that?  Are
there two independant antennas supported by the same physical structure, or
do they somehow mix their signals to feed the same antenna?

	As far as I know, there are no studios at the transmitting site;
there is just a small house which looks like it is probably big enough to
hold the actual transmitting gear, a couple of guys on duty watching it,
and maybe an emergency generator.  How do they get the audio signal from
the studio to the transmitter?  Plain old leased phone lines?  Private
microwave link?

	There are actually two towers, one rather smaller (1/2 as high?)
than the other.  I've always assumed that the smaller tower supported a
second antenna element to provide some directionality to the signal, as the
tower is at the extreme NE corner of New York City (actually on a tiny
island in Long Island Sound).  Is that likely the real reason for the
second tower?  My knowledge of antenna theory is pretty weak, so I'm not
really sure if my guess is even reasonable.
--
Roy Smith, Public Health Research Institute
455 First Avenue, New York, NY 10016
roy@alanine.phri.nyu.edu -OR- {att,cmcl2,rutgers,hombre}!phri!roy
"Arcane?  Did you say arcane?  It wouldn't be Unix if it wasn't arcane!"