Abstract :
Extensive use was made during the war of a new type of navigational beacon system using radar principles, the technical considerations of which are fully discussed in this paper. A description of the basic system is given in the introduction, together with a general review of the various applications of such a system by all three Services. The special technical problems involved in both airborne and ground equipments are dealt with at length in Section 2, thus preparing the reader for the detailed descriptions of particular equipments which follow. It is shown how the identification system (I.F.F.) developed, and how these early I.F.F. equipments were adapted to provide simple aids to navigation in the form of radar beacons which could supply range and heading information on the cathode-ray-tube display of early radar anti-shipping (A.S.V.) and air interception (A.I.) systems, thus enabling the aircrews to locate their home aerodromes. These early beacons soon established themselves, and a series of equipments in the 200-Mc/s frequency band, known by the code name ¿Rebecca-Eureka,¿ were developed to enable aircraft not fitted with search radar to make use of the beacon navigational system. A discussion follows on the application of the system to aid the approach and landing of aircraft under conditions of bad visibility, using a beacon equipment known as the Beam Approach Beacon System (B.A.B.S.). A brief outline is then given of some of the special developments of the system to meet various war-time operational requirements of all three Services. The paper concludes with a review of the present trends in interrogator-beacon development for use by both military and civil aviation in the more immediate future.
