Influence of a Radome on Antenna Performance

Michael Frech Meteorologisches Observatorium Hohenpeissenberg, Deutscher Wetterdienst, Hohenpeissenberg, Germany

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Bertram Lange Deutscher Wetterdienst, Hamburg, Germany

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Theo Mammen Deutscher Wetterdienst, Hamburg, Germany

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Joerg Seltmann Meteorologisches Observatorium Hohenpeissenberg, Deutscher Wetterdienst, Hohenpeissenberg, Germany

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Chris Morehead Enterprise Electronics Corporation, Enterprise, Alabama

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Joshua Rowan Enterprise Electronics Corporation, Enterprise, Alabama

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Abstract

The German Meteorological Service [Deutscher Wetterdienst (DWD)] operates the German weather radar network and is currently replacing all radar systems with new dual-polarization radars. One of the key components of a radar system is its antenna. The quality of the dual-polarized (dual-pol) moments is dependent on the quality of the antenna and its proper characterization. Dedicated on-site antenna pattern measurements with and without radome are performed in order to verify the antenna and radome specification of the new Hohenpeissenberg radar. Those on-site measurements are carried out from three different source sites in the far field of the antenna. The pattern measurements show that the main antenna specifications, such as the 3-dB beamwidth, beam squint, and sidelobe levels, are met. This is also true if a radome is in place. However, the data suggest that the manufacturer’s specifications are not fulfilled completely. This study finds a substantial increase of the copolar power level off the main beam. The homogeneity of the main beam with respect to differential power and phase is degraded with the radome. The measurements based on the three source sites indicate that a small (but negligible) radome-induced azimuthal variability of the radar moments can be expected. The integrated cross-polarization ratio based on the pattern measurement suggests that 1.4 dB of sensitivity is lost in the linear depolarization ratio (LDR) due to the dry radome.

Corresponding author address: Michael Frech, Meteorologisches Observatorium Hohenpeissenberg, DWD, D-82383 Hohenpeissenberg, Germany. E-mail: michael.frech@dwd.de

Abstract

The German Meteorological Service [Deutscher Wetterdienst (DWD)] operates the German weather radar network and is currently replacing all radar systems with new dual-polarization radars. One of the key components of a radar system is its antenna. The quality of the dual-polarized (dual-pol) moments is dependent on the quality of the antenna and its proper characterization. Dedicated on-site antenna pattern measurements with and without radome are performed in order to verify the antenna and radome specification of the new Hohenpeissenberg radar. Those on-site measurements are carried out from three different source sites in the far field of the antenna. The pattern measurements show that the main antenna specifications, such as the 3-dB beamwidth, beam squint, and sidelobe levels, are met. This is also true if a radome is in place. However, the data suggest that the manufacturer’s specifications are not fulfilled completely. This study finds a substantial increase of the copolar power level off the main beam. The homogeneity of the main beam with respect to differential power and phase is degraded with the radome. The measurements based on the three source sites indicate that a small (but negligible) radome-induced azimuthal variability of the radar moments can be expected. The integrated cross-polarization ratio based on the pattern measurement suggests that 1.4 dB of sensitivity is lost in the linear depolarization ratio (LDR) due to the dry radome.

Corresponding author address: Michael Frech, Meteorologisches Observatorium Hohenpeissenberg, DWD, D-82383 Hohenpeissenberg, Germany. E-mail: michael.frech@dwd.de
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