Low-cost landing system

When visibility is poor, instrument landing systems (ILS) create a "picture" of the runway for pilots so that they can bring a plane down more safely. But because most systems involve extensive and expensive equipment installation on the ground and in the aircraft, only the busiest airports are equipped. A new, low-cost instrument landing system promises to make ILS more affordable for more airports.

Based on monolithic millimeter-wave integrated circuits, the system uses a single, fixed, on-board multi-beam antenna system, called a radiometer, and six RF beacons on the ground. Four beacons outline the runway, and two more widely spaced apart provide a more accurate indication of range.

Since the system uses a minimal amount of equipment, it doesn't produce a "camera-like" picture. However, overlapping RF beams provide an accurate image of the runway relative to the aircraft. Each ground-based emitter uses an amplitude-modulated frequency. Narrow, millimeter-wave-receiving signals from the antenna pick up the RF transmission. Then conversion circuitry converts them into video signals that can be segregated by a fast Fourier transform processor. Another application of the millimeter-wave technology is in a fully populated focal plane array.

Merit Shoucri, TRW, 1 Space Park, Redondo Beach, CA 90278; Tel: (310) 812-5161; E-mail: [email protected].

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