Development of a High Performance Offset Gregorian Antenna for the Colorado State University (CSU)-CHILL National Radar Facility

根据该MRI，主要研究者将为科罗拉多州立大学（CSU）-CHILL雷达设施开发、获取、安装和测试一种新的高性能偏置格里高利天线。 CSU-CHILL雷达设施已由CSU作为多用户设施运营多年，可供所有合格的研究人员使用。 该设施主要通过CSU和NSF之间的合作协议提供支持。新天线的规格非常严格，推动了天线设计和制造技术的发展。 预计目前CSU-CHILL天线的旁瓣电平将大幅降低。 这一改进源于偏置格里高利设计，该设计消除了喇叭天线和馈源支撑支柱的阻塞。 交叉极化水平预期在任何平面中小于-35dB。 与当前天线相比，在所有平面上的二维积分交叉极化能量与共极化能量的比率预计将降低约10 dB。 这些对应于预期（双向）旁瓣杂波到主瓣信号功率的显著降低（16-20 dB），以及相对于主偏置设计，由双偏置设计提供的辐射偏振纯度的显著改善。在强空间梯度存在的情况下，需要这些高天线性能水平来精确测量常规多普勒数据和全极化协方差矩阵降水回波的强度，特别是在强风暴中。 目前，即使在存在适度降水回波空间梯度的情况下，在馈源支撑支柱的平面附近的相对较差的旁瓣性能也倾向于在许多关键极化测量中引起大的误差。 新的天线性能预计将增加近一倍的降水回波空间梯度，可以容忍没有显着的错误，在极化测量。 它还将大大提高常规多普勒数据的质量，特别是在通过数值模型进行数据同化方面。 新的天线将允许使用完整的协方差矩阵进行尖端研究，以大大改善云和风暴微观物理学的定量遥感，并可能在未来使用数值模型同化偏振数据。 这将是世界上唯一一个在S波段工作频率上进行研究的天气雷达。在过去几十年里，利用天气雷达进行遥感是许多气象进步的推动力。 这些进展包括对雷暴、山洪暴发、龙卷风、飓风和微暴流等恶劣天气现象有了基本了解。 这些知识大部分带来了实际的社会效益，例如业务气象机构采用的雷达预警系统。 多年来，CSU-CHILL设施为这一知识库作出了重大贡献。 新的天线系统将有助于保持什么是强大的，正在进行的研究和教育活动在雷达气象研究的前沿。

Under this MRI, the Principal Investigator will develop, acquire, install and test a new high performance offset Gregorian antenna for the Colorado State University (CSU)-CHILL radar facility. The CSU-CHILL radar facility has been operated for many years by CSU as a multi-user facility available to all qualified researchers. The facility is supported primarily through a cooperative agreement between CSU and NSF. The specifications for the new antenna are stringent and push the antenna design and manufacturing technology. A substantial reduction in sidelobe levels over the current CSU-CHILL antenna is expected. This improvement results from the offset Gregorian design that eliminates blockages by the feedhorn and feed support struts. The cross-polarization levels are expected to be less than -35 dB in any plane. The ratio of two dimensional integrated cross-polarized energy to copolarized energy over all planes is expected to be reduced by around 10 dB compared with the current antenna. These correspond to significant reductions in expected (two-way) sidelobe clutter-to-mainlobe signal power (16-20 dB), and significant improvement in the radiated polarization purity offered by the dual-offset design relative to the prime-focus parabolic reflector antenna.These high antenna performance levels are needed to accurately measure conventional Doppler data and the full polarimetric covariance matrix in the presence of strong spatial gradients of precipitation echo, especially in severe storms. Currently, the relatively poorer sidelobe performance near the planes of the feed support struts tends to cause large errors in many of the key polarimetric measurements even in the presence of modest precipitation echo spatial gradients. The new antenna performance is expected to nearly double the precipitation echo spatial gradient that can be tolerated without significant error in the polarimetric measurements. It will also greatly improve the quality of conventional Doppler data especially in the context of data assimilation by numerical models. The new antenna will permit cutting-edge research using the full covariance matrix to greatly improve the quantitative remote sensing of cloud and storm microphysics, and possibly in the future use of assimilation of polarimetric data by numerical models. It will be the only such research weather radar of its kind in the world at S-band operating frequency.Remote sensing using weather radar has been the impetus for many meteorological advances over the last few decades. Such advances have included gaining fundamental understanding of severe weather phenomena such as thunderstorms, flash floods, tornadoes, hurricanes and microbursts. Much of this knowledge has led to practical societal benefits such as radar warning systems that have been adopted by the operational weather agencies. The CSU-CHILL facility has made substantial contributions to this knowledge base over the years. The new antenna system will help keep what are robust, ongoing research and educational activities at the cutting edge of radar meteorological research.