TRE-920 TCAS Directional Antenna is part of the Rockwell Collins TCAS-94 system. The TCAS-94 system consists of the TTR-920/TTR-921 TCAS Receiver-Transmitter, two TRE-920 TCAS Directional Antennas (or one TRE-920 and one omnidirectional L-band antenna), two Mode S diversity transponders (or one Mode S diversity and one no diversity) with antennas and the TCAS Control. The TCAS-94 equipped aircraft transmits an interrogation signal, the transponder addressed aircraft replies, as the reply signal is received through the TRE-920 directional antenna, and processing circuits in the TTR-920/TTR-921 determine the direction of the aircraft.

The TRE-920 directional antenna mounts on the top and bottom of an aircraft and connects to the TTR-920/921 receiver-transmitter. There are no operator controls or adjustments on the TRE-920 antenna. The TRE-920 directional antenna requires four antenna cables. . The weight for the TRE-920 is 2.1lb, measurements are height 1.30in, width 6.30in, and length 11.2in.