The Honeywell ANT-67A Directional Antenna allows the bearing of intruder aircraft to be determined by providing the means for the TCAS processor to transmit interrogations and receive reply receptions on one of four antenna beams. By selecting the beam, the TCAS processor electronically points the antenna in a surveillance direction during TCAS transmit and receive operations.

The  top directional antenna is mounted at or near the longitudinal centerline of the aircraft ± 5 degrees and as far forward as is practical. The bottom directional antenna or omni antenna (if used) is collocated as near as possible to the vertical plane of the top directional antenna. During TCAS receptions, each of the four directional antenna elements receives any 1090 MHz signal that passes by the element. The phasing of these received signals is determined by the direction from which the rf energy is received. These signals are directed onto the same four cables that connect transmit signals between the TCAS processor and ANT-67A. The ANT-67A is a passive device and does not require aircraft power.