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From: rats@ihlpm.att.com (David Woo)
Newsgroups: sci.military
Subject: Re: Airborne Radar
Message-ID: <1991Mar1.053813.794@cbnews.att.com>
Date: 1 Mar 91 05:38:13 GMT
Sender: military@cbnews.att.com (william.b.thacker)
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From: rats@ihlpm.att.com (David Woo)


|From: yarvin-norman@CS.YALE.EDU (Norman Yarvin)

|Second, radars on fighters seem to be located in the nose cone, and to point
|forward.  The AWACS planes seem to have a large radar, in the shape of a
|disc attached to the top of the plane.  What is the mechanism these radars
|use to scan their beams?  I know of two classes of mechanisms: phased-array
|grids, and the rotation of an antenna.  These don't need to be visible; they
|might be concealed/protected behind radar-transparent material.  Is the
|AWACS's disk shielding a rotating antenna?  And what sort of mechanism can
|fit in a fighter's nose?

AWACS uses a rotating antenna underneath the rotating radome. 

Fighter aircraft can use a mechanical fully-scanned radar. Other
possibilities include a mechanically scanned phased-array radar.

Why, per chance, do you want a mechanically scanned phased-array radar?
Because a phased-array radar may be limited in it's angle of scan
via electronic means. Some versions of American cruise missiles use
a mechanically scanned phased-array radar for precisely this reason.

Previously, many American military aircraft utilised hydraulics to
scan the radar antennas. Advances in brushless DC motordrive technology
have allowed these troublesome beasts to be replaced with electric
actuators. It allows for new possibilities, for example, Wright-Patterson
was working on replacing the old actuators on the C-130 radar with
superior actuators to allow the C-130 to become terrain following,
like the F-111. However, the project was killed to to lack of funds.