Transponders

Eric Greenwell wrote:
...
I'm guessing the relatively slow speeds (compared to the airliner) and
low G turns of a glider (compared to a fighter, for example) would still
allow the TCAS to sort things out to the benefit of all concerned. At
the least, the TCAS is providing bearing, and altitude to the
glider, a big improvement over a pair of eyeballs looking out a window
going 300 knots.


I understand clearly how the TCAS can determine range and altitude (by
timing the return and decoding the encoded altitude), but how can it
determine the bearing? directional antennas coupled with compass information?