This International GNSS Service (IGS) Choke Ring Antenna designed by NASA/JPL and machined to Leica Geosystems' exacting standards, features superior multipath rejection with uncompromised phase center stability (<1mm) and is resistant to RF jamming.

The Choke Ring is the required standard for permanent GNSS networks around the world. Available with Leica Geosystems radome for weather protection.

The antenna is available as AT504 GG (GPS/GLONASS) version. The AT504 (GPS-only) is no longer available.