When sourcing GNSS RTK antennas, you must prioritize Multi-Band and Multi-Constellation support (GPS, GLONASS, Galileo, BeiDou) to ensure rapid signal acquisition and high reliability. Key technical metrics include Phase Center Stability (PCS), which should be sub-millimeter for geodetic applications, and a High Gain (typically >3dBi) to capture weak signals. Additionally, ensure the antenna features Advanced Multipath Mitigation technology to filter out reflected signals in urban or obstructed environments.