Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!newstop!sun!amdcad!amdcad!military
From: caf@omen.UUCP (Chuck Forsberg)
Newsgroups: sci.military
Subject: Re: Bistatic Radar
Message-ID: <1991Apr4.042304.12387@amd.com>
Date: 3 Apr 91 10:31:38 GMT
References: <1991Apr2.064909.14705@amd.com>
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From: caf@omen.UUCP (Chuck Forsberg)

> From: micquis!john@asuvax.eas.asu.edu (John Moore)
> Regarding discussions of passively tracking via radar:
> It is possible to use signals from an independent source to passively track
> aircraft.  There was an experiment done some years ago where aircraft in the 
> vicinity of LAX were tracked by a passive radar system. It used the signals 
> from a TV satellite as the emitter. It worked!

TV Satellite?  The most powerful TV satellites are about 50 watts.  That
50 watts is thinly spread over a wide area.  One might be able to paint a
Visitors' Mother ship with such a signal, but even a C5 might be too
stealthy.

A UHF TV station, with peak ERP in the megawatt range, sounds
more likely.  The receiving antenna would require extremely low
sidelobes to reject the much more powerful signal of the transmitter.
(Unlike radar, the TV carrier never shuts up.)

A BBC program on the early development of radar demonstrated airplane
interference (flutter) on a nearby 6 mHz shortwave station.  Which raises
the question: how low a frequency can radar operate on?  Not counting over
the horizon types, the lowest I've heard of is 30 mHz.  Would the British
WWII early warning radar pick up stealth A/C?

-- 
"Compared to tanks, journalists are cheap - and you get more for your money."
		- Saddam Hussein