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A pair of production Wedgetail AEW&C aircraft (Boeing).
Wedgetail Apertures
The most prominent of the many antenna and optical apertures is the MESA “top hat” AESA antenna subsystem shared between the L-band radar and its integrated IFF system. This design is both innovative but also the principal cause of numerous development problems which resulted in a four year delay against the intended schedule and loss in capability against the initial specification.
The dorsal fin mounts the transmit/receive elements for the left and right looking MESA slab arrays. These are a very conventional planar AESA design. The close proximity between the lower edge of the array and upper fuselage presents some problems with coupling between near field lobes and the aircraft structure. The MESA will provide reasonable heightfinding capability as the ~3:1 ratio permits sufficient phase difference across the vertical dimension of the array.
The cavity endfire antenna mounted on top of the dorsal fin is intended to provide coverage over the nose and the tail of the aircraft. This design is the first attempt at a production cavity endfire array. It can provide beamsteering in the horizontal plane, generating a vertical fan shaped beam. The internal arrangement is a lower surface with an array of radiating elements, described as a “bed of nails” and a upper surface which is a conventional waveguide arrangement. The design radiates, subject to element phase control, out of the front or the rear openings in the cavity. Public disclosures are insufficient to determine the extent to which the close proximity of the fuselage and tail surfaces impacted performance either by shadowing, near field coupling, or far field reflection1.
The MESA radar is supplemented by a variant of the BAe Systems Australia ALR-2001 Odyssey ESM system, based on the Israeli Elta EL/M-8300 (8382) series ESM/ELINT system, which employs a suite of four antenna systems for the microwave bands, mounted under nose, tail and wingtip radomes, and a suite of ventral antennas for the lower bands. Cited EL/M-8300 (8382) performance parameters are a DF accuracy under 1°, instantaneous bandwidth of ~4 GHz, sensitivity between -70 and -85 dBm, and band coverage between 500 MHz and 18 GHz. The production installation may employ optical links for RF signal transmission through the airframe2,3.
RF antennas for the extensive C3 suite, covering voice and data channels, are located primarily on the ventral and dorsal fuselage centrelines.
Three sets of optical apertures are employed. The AAR-54 MAWS has paired apertures on the nose and tail ESM antenna pedestals, with supplementary dorsal and ventral apertures cited but not validated by imagery. The LWS-20 laser warning system has individual apertures provisioned for along the fuselage - the status of the installation has not been disclosed. Finally the AAQ-24 DIRCM has a reserved location under the tail ESM antenna fairing, but this device has yet to be observed installed on the aircraft.
Wedgetail AEW&C Prototype in 2005
Head on view of the first prototype (Author; M645/1000S).
Ventral nose ESM antenna radome assembly. Note the red covers over the AAR-54 MAWS apertures (Author; M645/1000S).
Profile view of nose radomes. Note the circular LWS-20 laser warning receiver aperture below the aft cockpit window (Author; M645/1000S).
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