Antenna Models

The purpose of an antenna model is to:

• Correct for the vertical offset between where GNSS observations are observed (the electronic phase center) and the bottom of the antenna (Antenna Reference Point, or ARP).

• Correct for any difference between the L1 and L2 electronic phase centers, which can be a factor in the success or failure of ambiguity resolution.

• Apply elevation based corrections

Calibrated absolute antenna models published by IGS and NGC in the ANTEX format are supported. If the antenna model is not known at your remote, it is recommended that the Generic profile be applied, which does not apply any corrections. In that case, the processed positions are referenced to the antenna L1 phase center, or as best can be estimated without applying the antenna model. The correct antenna model should be selected for best results.

When selecting an antenna model, the ARP to L1 offset reflects the vertical difference between the L1 phase center and the ARP (which is the bottom of the antenna). This value comes directly from the antenna model and reduces the processed position from the phase center to the ARP. This value should match any diagram that appears directly on your antenna, presuming it is an absolute antenna calibration. Antenna heights can be measured to the antenna reference point, phase center, or computed from a slant measurement.

When loading a base station converted from RINEX, the antenna name and radome (if provided) are scanned from the RINEX header and used to automatically load the appropriate antenna profile. It is good practice to ensure the correct antenna model is loaded prior to processing.

Waypoint does not perform antenna calibration. If your antenna model is not included in the Waypoint software, ask your antenna manufacturer to have the antenna calibrated through IGS.