Enhanced Multipath Rejection GPSAntenna GA41

Features

• Multipath rejection

• Stable phase center

• Navigational data directly fromGPS satellites

• 29 dB pre-amplifier

• Band-pass filter providesimmunity to interference

• Protective epoxy coating

GA41 is designed to give the bestpossible local GPS signal reception inconnection with the new generationRS41 radiosonde measuring GPS basedpressure. GA41 antenna design has anexcellent multipath rejection and a highlystable phase center, improvingthe accuracy of calculated height andatmospheric pressure profiles. Multipathoccurs when GPS signal arrives atthe GPS antenna from more than onepropagation route i.e. multiplepropagation paths.

Vaisala Sounding System gets orbital andother navigational data directly fromthe GPS satellites through GA41 antenna.The local reception is also used tocalculate differential corrections forpositioning.

InstallationGPS signal reception requires anunobstructed line-of-sight to the GPSsatellites as far as possible fromreflective surfaces. Installation sites on

sheet metal roofs, water bodies invicinity or with prominent reflectivestructures near the antenna requirea high performance GA41 antenna toobtain the specified GPS-based pressureaccuracy. The best reception is achievedwith a location that has a clear view ofthe sky down to the horizon in everydirection.

GA41 is equipped with a 29 dB pre-amplifier. A band-pass filter rendersthe antenna immune e.g. to Inmarsat orradar interference. GA41 is sealed withepoxy for protection against ambientconditions. It is shipped with a 1.5-meteraluminium pole with a cast-aluminiumflange and pole mounting clips and33 meters of cable.

Enhanced Multipath Rejection GPS Antenna GA41 isdesigned to give the best possible local GPS signalreception in connection with the new generation RS41radiosonde measuring GPS based pressure.

GA41 Technical Data

Operating EnvironmentOperating temperature -40 … +85 °C

Storage temperature -55 … +85 °C

Operating humidity 0 … 100 %RH

Storage humidity 0 … 100 %RH

Operating precipitation Unlimited

Maximum wind speed 65 m/s

Inputs and OutputsPrimary power +5 VDC (±10 %)

Power consumption 35 mA (nominal)

Output impedance 50 Ω

Operating frequency L1 (1575 MHz)

Polarization Right-hand circular polarization(RHCP)

Mechanical SpecificationsWeight (without cables) 2.9 kg

Height 1.6 m

Mounting Pedestal flange or pole clamps

Standard cable length 33 m

GeneralVSWR 2:1

Axial ratio < 1.5 dB (typically) above10° elevation

Gain 29 dB (nominal)

Noise figure 2.0 dB (nominal)

3 dB pass-band width 23 MHz (nominal)

Cable attenuation < 21 dB at 1.5 GHz

Azimuth coverage 360° (omni-directional)

Elevation coverage 0 … 90° (hemispherical)

Published by Vaisala | B211319EN-B © Vaisala 2017

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