5.3 Definition of "Nullantenna" and Antenna Type "Nullantenna"

Definition "Nullantenna"

The Nullantenna has an absolute and isotropic characteristic. Hence, the Nullantenna has no PCV. The PCV are reduced to an antenna reference point (ARP) in order to avoid problems arising from a mean phase center (i.e. dual frequency antenna).

Realization "Nullantenna"

A realization of a Nullantenna is an actual antenna corrected by absolute PCV with its associated standard deviations.

"Nullantenna" for Absolute PCV

The absolute PCV for a Nullantenna are, corresponding to the definition, null for offsets and PCV.

"Nullantenna" for Relative PCV (refering to IGS/NGS Reference Antenna)

The relative antenna type Nullantenna (refering to the IGS/NGS reference antenna) is required for consistency with the currently existing relative PCV tables. This can be derived from an absolute PCV calibration of the IGS/NGS reference antenna (i.e. AOAD/M_T).

The PCV of the antenna type Nullantenna relative to the IGS/NGS reference antenna is derived from the AOAD/M_T, SN 404, absolute PCV field calibration in the following manner:

The antenna type Nullantenna must be incorporated into the IGS rcvr_ant.tab as well as into the IGS igs_01.pcv  and into the NGS ant_info.003 relative PCV tables.
Last update: 17.05.2001 by Geo++