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POLDIRAD

Fast Calibration of Weather Radar Systems for Multi Polarization Radar Measurements Jens Reimann, Martin Hagen DLR-Institute of Atmospheric Physics. POLDIRAD. Research Radar C-Band Doppler Weather Radar Polarization agile: Tx/Rx any Polarization Switch Polarization every Radar Pulse.

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POLDIRAD

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  1. Fast Calibration of Weather Radar Systems for Multi Polarization Radar MeasurementsJens Reimann, Martin HagenDLR-Institute of Atmospheric Physics

  2. POLDIRAD Research Radar C-Band Doppler Weather Radar Polarization agile: Tx/Rx any Polarization Switch Polarization every Radar Pulse

  3. Polarization Network High Power Ferrite Phase Shifter Not Linear, not Reciprocal Changing Losses No “a priori” known polarization Schematics Variable Power Divider Phase Shifter

  4. Requirements • Fast → adjust polarization switch settings • Measure any Polarization • Independent Rx/Tx measurements • Repeatable

  5. Polarimetric Calibration (PARC) Far Field Polarization determination by Power and Phase measurement Simple two channel Rx/Tx frontend Commercial SDR card, Measure every Pulse Data analysis in Software Radar

  6. Polarimetric Calibration (PARC) Very flexible: Polarization measurement Power calibration PRF Frequency Pulse shape Independent Rx/Tx Measurement Automatic Calibration Polarimetric Antenna Pattern Calibrated: H, V, 45°, 135°, R, L

  7. Scan Strategies • H/V-Switching Mode • Tx: alternating H and V • Rx: both H and V Full Scattering Matrix R/L-Mode Hybrid/STAR-Mode • Tx: 45° linear • Rx: both H and V Only two parameters t t+1 • Full description for further calculation: • Optimal Polarization • Huynen Parameters

  8. Multi Polarization Radar Measurement Combination of H/V-Switching and STAR-Mode Tx V V 45° 45° H H Rx t H/V H/V H/V H/V H/V H/V STAR- Mode STAR- Mode H/V-Mode H/V-Mode

  9. Combination of Polarimetric Modes H/V- and STAR-Mode • Simultaneous measurement in H/V- and STAR-Mode • Direct comparison • For high Depolarization → large discrepancy

  10. Combination of Polarimetric Modes Two STAR-Modes • Polarimetric Sensitivity Analysis • Transmit: Circular and Linear Tx R 45° 45° Rx t H/V H/V H/V STAR- Mode I STAR- Mode II STAR- Mode I • Any Combination of R/L,H/V, STAR-Mode possible

  11. Huynen-Parameters Example: 24. Aug 2011, 17:58, near Alps, Germany Orientation TargetSize • Decomposition • Phenomenological Description • Polarization Independent • Insight into Scattering Mechanism Ellipticity

  12. Conclusion Calibration Very flexible, automatic calibration device Adaptable for other radars Measurement First Results for Multi Polarization Measurements Influence of Polarization Errors Huynen-Parameter

  13. Contact Dipl.-Ing. Jens Reimann <Jens.Reimann@dlr.de> German Aerospace Center Institute for Atmospheric Physics Muenchner Strasse 20 82234 Oberpfaffenhofen-Wessling, Germany

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