Beacon Splits in Air Traffic Control Radar Beacon System (ATCRBS)

The ATC radar beacon system is today's primary source of surveillance ance data for air traffic control. For en route traffic control, radar and beacon data are collected at numerous long range radar (LRR) facilities and typically sent by remote control to the air traffic control center (ARTCC) by a radar microwave link (RML). Selfsupporting or guyed RML towers are installed at some LRR sites adjacent to the LRR antenna to establish a line-of-sight microwave path to the first repeater site. For these LRR sites, beacon splits and pulse-stretching effects have been observed particularly in the direction of the RML tower. This paper relates to the determination ion of the magnitude of the beacon split problem for such sites and the extent to which this problem is caused by the RML tower. It has been shown that the RML tower causes distortion in the patterns of both the directional and omnidirectional antenna. The nature and extent of these distortions are such that they tend to nullify the advantages achievable by the SLS and ISLS techniques. Consequently, the beacon split phenomenon may be referred to more specifically by the well-known "ring-around" effect. Finally, the paper makes a few recommendations for eliminating or reducing this problem.