Onsite dualpol antenna performance verification

A critical component of a dualpol radar system is the antenna. A very good matching of the H and V characteristics in transmit and receive mode is a prerequisite to ensure high dualpol data quality.The main beam in H and V requires a good matching in all planes. Furthermore it is necessary to achieve low side-lobe levels in all planes including the struts. Low side levels are important in low reflectivity situations where clutter echoes may cause bad signal quality. The requirement to the antenna performance are more stringent for a dualpol system as compared to a Doppler system.

At the DWD Hohenpeissenberg meteorological observatory site a dedicated antenna pattern measurement program has been carried out in Spring 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.

We use the DWD radar software MURAN and the radar receiver to sample 3-D volume data which allows subsequently for a detailed analysis of the antenna characteristics. The onsite measurements with and without radome are also used to analyse the radome influence on the dualpol radar perfomance (see other abstract by Frech et al.) 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. We discuss the general on-site measurement setup, the measurement strategy, the analysis procedure, the results and the implications on the data quality.