X-Band Dual-Polarization Phased Array: Calibration and Performance

近年来，随着国家天气雷达试验台和快速扫描移动多普勒相控阵雷达(如Rapid-Dow、MWR-05XP和大气成像雷达)等研究平台的发展，相控阵技术在气象领域的应用已经实现。随着这些举措以及多任务相控阵雷达和大气协作自适应传感中心(CASA)等举措的实施，人们对相控阵雷达在天气监测和测量方面的潜力越来越感兴趣。然而，由于美国现役天气雷达网现在采用双极化，预计未来的相控阵系统将需要支持极化，以改进水星识别和降雨估计，并具有与目前反射面天线相同的保真度。微波遥感实验室与CASA工程研究中心合作，最近开发了一种移动式、双极化、固态、X波段有源相控阵天气雷达。获得这一奖项后，将对这种有源相控阵雷达进行实验，以研究其极化性能、校准和稳定性、偏差以及相控阵天气雷达天线特有的其他不确定性。该阵列将用于具体部署和获得相控阵雷达极化实用化经验的机会试验，并将在当地进行校准试验和在大平原部署。特别是，该雷达将在连续两个春季部署到达拉斯/沃斯堡城市试验台，这是一个由CASA工程研究中心发起、主要由北德克萨斯州政府委员会赞助的准作战/研究雷达网。在这里，相控阵雷达将与其他类似大小的X波段机械扫描双极化雷达一起观测恶劣天气。这项研究的学术价值在于用实际的双极化相控阵雷达对极化缺陷和投影误差的影响及其补偿进行了实验研究，并用低成本的相控阵对波束质量(旁瓣、H、V极化波束的精确匹配、交叉极化)进行了表征。性能将通过校准目标和天气观测以及配套的机械扫描天线进行基准测试。这项研究的更广泛影响是提高了对严重风暴及其形成的运动学和动力学的理解，最终导致对恶劣天气事件的预测得到改善。在天气观测中采用新技术也将使用户对这些目的的雷达测量的解释和期望有所了解。此外，该项目还包括来自马萨诸塞州大学的研究生与DFW测试床的研究人员和用户的密切合作。在部署期间，相控阵雷达还将作为麻省理工大学和德克萨斯阿灵顿大学的教学工具。

The advent of phased array technology for meteorological applications has been realized recently with the development of research platforms such as the National Weather Radar Testbed and mobile Doppler phased array radars for rapid scanning such as the Rapid-DOW, MWR-05XP, and Atmospheric Imaging Radar. With these and initiatives such as the Multi-mission Phased Array Radar and the Center for Collaborative Adaptive Sensing of the Atmosphere (CASA), there is growing interest in the potential for use of phased array radars in weather surveillance and measurement. However, because the operational weather radar networks in the U.S. are now adopting dual polarization, it is anticipated that it will be necessary for future phased-array systems to support polarimetry for improved hydrometeor identification and rainfall estimation, with the same fidelity as is possible with today's reflector antennas.The Microwave Remote Sensing Laboratory in collaboration with the CASA Engineering Research Center, has recently developed a mobile, dual-polarization, solid-state, X-band active phased-array weather radar. With this award, experiments will be performed with this active phased-array radar to study its polarization performance, calibration and stability, biases, and other uncertainties particular to phased-array weather radar antennas. This array will be used in specific deployments and experiments of opportunity to gain experience in the practicalities of phased-array radar polarimetry.A combination of calibration experiments will be performed locally as well as deployments to the Great Plains. In particular, the radar will be deployed during two successive spring seasons to the Dallas/Fort Worth Urban Testbed, a quasi-operational/research radar network initiated by the CASA Engineering Research Center and primarily sponsored by the North Texas Council of Governments. Here, the phased-array radar will observe severe weather in tandem with other similarly sized, X-band, mechanically scanned dual-polarization radars. The intellectual merit of the research is experimental investigation of the impacts of polarization imperfections and projection errors and their compensation with a real dual-polarization phased-array radar, as well as characterization of the beam quality (sidelobes, precise matching of H- and V-polarized beams, cross-polarization) with a low-cost phased array. The performance will be benchmarked both via calibration targets and observations of weather with companion mechanically scanned antennas. The broader impacts of the research are improved understanding of the kinematics and dynamics of severe storms and their formation, ultimately leading to improved predictions of severe weather events. The incorporation of new technologies in weather observation will also inform users' interpretations and expectations of radar measurements for these purposes. In addition, the project includes strong involvement of graduate students from UMass working with investigators and users of the DFW Testbed. The phased-array radar will also serve as a teaching tool at UMass and at U. of Texas Arlington during deployments.