Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!texbell!vector!telecom-gateway
From: mlr@houtz.att.com (Michael L Robins)
Newsgroups: comp.dcom.telecom
Subject: Re: Cellular Telephone Causes Airline Fire Alarm
Message-ID: <telecom-v09i0339m05@vector.dallas.tx.us>
Date: 30 Aug 89 18:39:36 GMT
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X-TELECOM-Digest: volume 9, issue 339, message 5 of 8

Although there has been much discussion about cellular and Airphone radio
services aboard airplanes, early propagation work in Chicago revelaed that the
radio pattern for cellular is kind of a mushroom shape, and at the height of
airplanes >10,000 feet, I suspect that you would never be able to receive a
signal from a cell site. This was even true on top of the Sears Tower in
Chicago, and although a cell cite was easily in view, and about 3 blocks away,
it was about 4 hundred feet below, and we found that we were never even able
to talk to that cell site because of the shape of the radio signal.  We found
that we were always talking to a cell site much further away. An example is
below:
                                          /    airplane
                                     o--/----/
                       ant               \
      ________          |        ________  \
    /          \        |      /          \
  /      |       \      |    /              \
 /    car|         \    |   /                 \
/    O---O           \  |  /                    \

Notice that when the plane is in the air that it is above the node of the
signal while the car on the ground works just fine.