The 21-20-85-1 VOR/ILS LOCALISER AND GLIDESLOPE antenna system comprising of a pair of high-strength blades (P/N 21-20-85A and 21-20-85B) for horizontal mounting, one on each side of a vertical stabiliser, together with an external cable harness (P/N 21-80-56).

When installed, the blades act as a loop for VOR/LOC and as a forward looking dipole for GLIDESLOPE. The combined output from the 21-80-56 is connected to a diplexer/splitter (P/N 21-80-39) which divides the signal into separate VOR/LOC and GLIDESLOPE signals, both of which derive equally from each half of the antenna system, and then splits each signal in phase and amplitude. The system is thus capable of feeding twin VOR/LOC and Glideslope receivers.

Mechanical design of each blade comprises an internal printed circuit half loop, foamed-in-place into a high strength epoxy-glass radome fitted to an aluminum alloy base block having an integral mounting flange. Structural design ensures high side loading acceptance as required on high speed military aircraft.