Institute of Atmospheric Physics Fast Calibration of Weather Radar Systems for Multi Polarization Radar Measurements Jens Reimann, Martin Hagen DLR-Institute of Atmospheric Physics

Institute of Atmospheric Physics Slide 2 > Jens Reimann Outline Introduction Polarimetric Calibration Multi Polarization Measurements Conclusion

Institute of Atmospheric Physics Slide 3 > Jens Reimann POLDIRAD Research Radar C-Band Doppler Weather Radar Polarization agile: – Tx/Rx any Polarization – Switch Polarization every Radar Pulse

Institute of Atmospheric Physics Slide 4 > Jens Reimann Polarization Network High Power Ferrite Phase Shifter Not Linear, not Reciprocal Changing Losses No “a priori” known polarization Schematics Variable Power Divider Phase Shifter

Institute of Atmospheric Physics Slide 5 > Jens Reimann Requirements Fast → adjust polarization switch settings Measure any Polarization Independent Rx/Tx measurements Repeatable

Institute of Atmospheric Physics Slide 6 > Jens Reimann 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

Institute of Atmospheric Physics Slide 7 > Jens Reimann Polarimetric Calibration (PARC) Very flexible: 1)Polarization measurement 2)Power calibration 3)PRF 4)Frequency 5)Pulse shape 6)Independent Rx/Tx Measurement 7)Automatic Calibration 8)Polarimetric Antenna Pattern Calibrated: H, V, 45°, 135°, R, L

Institute of Atmospheric Physics Slide 8 > Jens Reimann Scan Strategies Hybrid/STAR-Mode Tx: 45° linear Rx: both H and V Only two parameters H/V-Switching Mode Tx: alternating H and V Rx: both H and V Full Scattering Matrix Full description for further calculation: Optimal Polarization Huynen Parameters R/L-Mode tt+1

Institute of Atmospheric Physics Slide 9 > Jens Reimann Multi Polarization Radar Measurement Combination of H/V-Switching and STAR-Mode t H V 45° H Tx Rx H/V V 45° H/V-Mode STAR- Mode H/V-Mode STAR- Mode

Institute of Atmospheric Physics Slide 10 > Jens Reimann Combination of Polarimetric Modes H/V- and STAR-Mode Simultaneous measurement in H/V- and STAR-Mode Direct comparison For high Depolarization → large discrepancy

Institute of Atmospheric Physics Slide 11 > Jens Reimann Combination of Polarimetric Modes Two STAR-Modes Polarimetric Sensitivity Analysis Transmit: Circular and Linear t 45° R Tx Rx H/V STAR- Mode II STAR- Mode I STAR- Mode I Any Combination of R/L,H/V, STAR-Mode possible

Institute of Atmospheric Physics Huynen-Parameters Decomposition Phenomenological Description Polarization Independent Insight into Scattering Mechanism Target Size Orientation Ellipticity Example: 24. Aug 2011, 17:58, near Alps, Germany

Institute of Atmospheric Physics Slide 13 > Jens Reimann Conclusion Calibration Very flexible, automatic calibration device Adaptable for other radars Measurement First Results for Multi Polarization Measurements Influence of Polarization Errors Huynen-Parameter

Institute of Atmospheric Physics Slide 14 > Jens Reimann Dipl.-Ing. Jens Reimann German Aerospace Center Institute for Atmospheric Physics Muenchner Strasse Oberpfaffenhofen-Wessling, Germany Contact