major@uunet.UU.NET (Mike Schmitt) (03/05/91)
From: bcstec!shuksan!major@uunet.UU.NET (Mike Schmitt)
In response to someone's question about airborne radar - AWACS
in particular. The following information comes from open sources,
specifically, a Westinghouse 'marketing' document with the caveat,
"This material has been cleared for public release in accordance with
DoD regulations"
The antenna array is housed in the rotodome - and the entire rotodome
revolves once every 10 seconds. The radar scans the area with a narrow
radar beam. The radar functions as both a pulse and/or a pulse-doppler
radar to detect air targets. For beyond-the-horizon targets a conventional
pulse radar is used. A pulse radar with pulse-compression and
sea clutter adaptive processing is used to detect maritime traffic.
Target reports contain elevation and azimuth angle, velocity, and range
for each target. The beam is narrow (horizontaly) to permit high
resolution to closly spaced targets and can be electronically scanned
vertically to obtain altitude measurements. These scans with the rotating
dome provide a 360-degree surveillance picture. Cruising at 30,000 feet
the E3 AWACS can detect targets within a 200 nautical mile radius.
There is an associated IFF radar.
The radar has several modes which the operators can select; Pulse-Doppler
Nonelevation, Pulse-Doppler Elevation, Beyond-the-Horizon, Maritime,
Interleaved, and Passive. Any azimuth scan can be divided into as many
as 32 sectors - each with its own operating mode.
Inside the rotodome the antenna array itself consists of the following:
- Stacked array of 28 slotted waveguides
- Reflectionless transmit and receive manifolds
- 28 reciprocal ferrite beam steering phase shifters
- 28 low-power nonreciprocal beam offset phase shifters
also inside: Phase shifter control unit
Thermal stabilization unit
Microwave receiver
mike schmitt