Onsite radome performance verification

An important component of a dualpol radar system is the radome. Aside from a reliable longterm protection of the radar system by the radome, the influence of the radome on HF properties of the transmitted and received signal should be small. In particular for dualpol applications this requirment is very important as it has been shown in various studies. For example differential moments may be affected by the radome (e.g. this may be visible in aziumthal variations in ZDR, as seen in orange-peel radomes). At the DWD Hohenpeissenberg meteorological observatory site, a dedicated antenna pattern measurement program has been carried out in April 2011 in order to measure and verify the dualpol antenna characteristics of the DWSR-5001/SDP/CE radar system from EEC which is introduced in DWDs' radar replacement project RadSys-E. The onsite antenna tests were performed in order to ensure that the antenna performance seen during FAT is also realized after the onsite installation. Those antenna tests have been performed with and without the new AFC STEALTH radome which has been designed for dualpol applications. This measurment campaign provides an unique data set to investigate the radome influence on the antenna performance. Aside from the analysis of antenna patterns, we will also investigate the performance under real weather with respect to for example differential attenuation effects. In this contribution we show results on the beam widths, the beam symmetry and matching, the beam squint, side lobe levels, cross-pol isolation and differential phase patterns for our new radar system with and without radome. We discuss the general on-site measurement setup, the measurement strategy, the analysis procedure, the results and the implications on the data quality.