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Trimble Zephyr Geodetic GPS Antenna

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Trimble Zephyr Geodetic GPS Antenna
Item ID: X3675
Condition: Refurbished
Warranty: 90 Day Exchange


* Trimble Zephyr Geodetic GPS Antenna P/N: 41249-00 [ID- X3675]


Trimble Zephyr Geodetic Antenna
The Trimble Zephyr and Zephyr Geodetic antennas are two types of survey-grade, dual-frequency, GPS antenna. They are designed to match the performance of the choke ring antenna, while being smaller, lighter, and significantly less expensive.

Both antennas are the result of intensive research and development, and utilize recent innovations in highperformance GPS antenna technology, for which patents have been issued to Trimble. The new antennas incorporate major advancements in:
  • Radio frequency antenna design
  • Advanced materials technology
  • High precision manufacturing techniques
  • Trimble Stealth Ground Plane technology
The result is antenna phase center (APC) repeatability and multipath resistance comparable to the choke ringóand improved tracking of low elevation satellites and in difficult environments.

The use of advanced materials enables the Trimble Zephyr and Zephyr Geodetic antennas to be extremely compact and lightweight. Although the antenna element and low noise amplifiers used today will need to be modified in order to be compatible with the future L5 second civil frequency, the underlying design of the new Trimble Stealth Ground Plane is independent of frequency. This will make it much more effective for use with the new frequency than more conventional ground planes.

Patented Antenna Element Design Achieves Sub-millimeter Repeatability
The GPS antenna element is the part of an antenna that is sensitive to energy transmitted from GPS. For precise GPS surveying, this element is usually a flat piece of metal called a ìpatchî antenna. It is usually round or approximately square, and its dimensions make it sensitive to the GPS frequency being tracked. When a GPS receiver/antenna combination is tracking satellites and making code and carrier phase measurements, the actual points in space between which those measurements are taken are the instantaneous phase centers of the GPS satellite and GPS receiver antennas.

Nominally, the GPS receiver antenna phase center is located at the center of this square patch, that is, at the mechanical center of the antenna. However, in practice the effective electrical center of the antenna moves around in three dimensions.

This is a function of the apparent azimuth and elevation of the satellite being tracked, and the way that the antenna is fed, that is, how it is electrically connected to the rest of the circuit. Because multiple satellites are tracked at any time, and each one has a different azimuth and elevation, each measurement is taken from a slightly different location in space, somewhere near the mechanical center of the antenna. Thus, although surveyors require a measurement at a single point in space at any point in time, their antennas take measurements from a group of electrical phase centers that are all at slightly different locations.

The space in which these electrical phase centers may vary is something like an error ellipsoid; consequently, if an antennaís variation is large, then its ellipsoid is also large.

An ideal GPS antenna for surveying would take all measurements from an exact, physically defined, mechanical location, regardless of satellite elevation angle or azimuth, or any other factor. Such an antenna would be said to have extremely good phase center stability.

13.5" diameter x 3" maximum depth
Weight: 2.2 lbs
Operating temperature range:  -40 to +70 C
100% humidity proof, fully sealed
Shock tested for a drop of 2 m onto concrete
Vibration tested to MIL-STD-810
4-point antenna feed for sub-millimeter phase center repeatability.
Integral Low Noise Amplifier
50 dB antenna gain
Trimble Stealth ground plane for reduced multipath