FRESNEL-ZONE MEASUREMENT AND ANALYSIS OF A DUAL- POLARIZED METEOROLOGICAL RADAR ANTENNA

摘要

The use of dual polarization in meteorological radars offers significant advantages over single polarization. Recently a standard single-polarization C-band radar was upgraded to operate in dual-polarization mode. The antenna has a 4.2m diameter parabolic reflector with a prime-focus feed. A spherical Fresnel-zone holographic technique was used to obtain the radiation pattern for the upgraded antenna. The sidelobes were higher than predicted and so the data was analyzed to identify the relative contributions of shadowing from the feed crook and surface errors in the dish. This paper describes practical considerations in the measurement of this antenna and the analysis of the results.