ULTRA-WIDEBAND 170 AND 240 GHZ CW SOURCE SWEEPING SYSTEMS

超宽带 170 和 240 GHZ CW 源扫描系统

• 批准号: 8363967
• 负责人: CURT R DUNNAM
• 金额: $ 0.78万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8363967
• 关键词: Area; Custom; Development; Diagnostic; Electron Spin Resonance Spectroscopy; Evaluation; Frequencies; Funding; Grant; Investigation; Measurement; Methods; National Center for Research Resources; Output; Performance; Phase; Predisposition; Principal Investigator; Procedures; Research; Research Infrastructure; Resources; Services; Source; Staging; System; Techniques; Technology; Testing; United States National Institutes of Health; Work; base; cost; design; design and construction; improved; instrumentation; millimeter; operation; programs

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Verification and tuning procedures related to bridge setup for ESR spectroscopy are, in general, greatly facilitated by swept-frequency measurement of transmitted/reflected power. Swept-frequency evaluation methods are especially useful in the millimeter-wave regime, and even more so when quasioptical techniques are employed, mainly due to the numerous interacting adjustments and enhanced quasioptical bridge susceptibility to extra-path reflections. As useful as swept measurement capability is, off-the-shelf test and measurement instrumentation providing phase-locked swept-frequency capability at even the lower millimeter-wave regime (i.e., below 100 GHz) is inordinately expensive and, above that frequency range, appears to be available only on an even more expensive custom-built basis. For this reason, ACERT had not previously invested in millimeter-wave swept-measurement capability for its 170 and 250GHz c.w. spectrometer bridges. Last year, ACERT acquired significantly improved millimeter-wave sources of center frequencies at 170 and 240 GHz for its high-field c.w. quasioptical ESR spectrometers. These units generate approximately 12dB more output power than the previous c.w. sources and provide phase-locked operation over a relatively broad frequency range of fc ¿ 5 GHz. In view of the significantly higher output power available from these sources, an extensive program of bridge and resonator design upgrades was undertaken for optimized bridge operation in inductive-reflection mode. During the course of this development work, it became evident not only that swept-frequency measurement capability would be indispensable, but also, conveniently, that these extended-range c.w. sources might be pressed into service for such incidental use. Our work to date in this area has resulted in an interim 170GHz swept-frequency system which has proven extremely useful in the setup and fine-tuning of the H.F. reflection bridge. We have found that, although the swept output power is not actively leveled, the source multiplier stage bias levels may easily be tuned to provide better than 1.2 dB flatness at fc ¿ 1.0GHz and approximately 3dB over the entire source tracking range from 165 to 175GHz. This performance level is more than sufficient for general bridge and resonator tuning procedures. Given the encouraging results thus far, we plan to continue this project over the coming year with similar investigation of the new 240GHz tracking c.w. source for swept measurements. During the coming year, we plan to continue with the design, construction, installation and programming of a simplified operator interface for switching between normal c.w. operation and the swept-frequency diagnostic modes.

该子项目是利用资源的众多研究子项目之一 由 NIH/NCRR 资助的中心拨款提供 该子项目的主要支持。 并且子项目的首席研究员可能是由其他来源提供的， 包括其他 NIH 来源的子项目可能列出的总成本。 代表子项目使用的中心基础设施的估计数量， NCRR 赠款不直接向子项目或子项目工作人员提供资金。 一般来说，扫描频率测量发射/反射功率可以极大地促进与 ESR 光谱电桥设置相关的验证和调谐过程，扫描频率评估方法在毫米波领域尤其有用，在准光学领域更是如此。技术的采用，主要是由于大量的交互调整和增强的准光桥对额外路径反射的敏感性，与扫频测量功能一样有用的是，提供锁相的现成测试和测量仪器。即使在较低毫米波范围（即低于 100 GHz）的扫频功能也非常昂贵，而在该频率范围之上，似乎只能在更昂贵的定制基础上提供。此前并未投资其 170 和 250GHz 光谱仪桥的毫米波扫描测量能力。 去年，ACERT 为其高场准光学 ESR 光谱仪采购了中心频率为 170 和 240 GHz 的毫米波源，这些装置的输出功率比以前的连续波源高出约 12dB，并可提供锁相操作。 fc 的频率范围相对较宽 ¿鉴于这些源可提供更高的输出功率，我们对电桥和谐振器设计进行了广泛的升级，以优化电桥在感应反射模式下的运行，这一点在开发工作过程中变得显而易见。扫频测量能力是必不可少的，而且方便的是，这些扩展范围的连续波源可以用于此类偶然用途。 迄今为止，我们在这一领域的工作已经产生了临时的 170GHz 扫频系统，该系统已被证明在高频反射电桥的设置和微调中非常有用。我们发现，尽管扫频输出功率没有主动均衡，可以轻松调整源乘法器级偏置电平，以在 fc ¿ 下提供优于 1.2 dB 的平坦度1.0GHz，在 165 至 175GHz 的整个源跟踪范围内大约为 3dB。鉴于迄今为止令人鼓舞的结果，该性能水平足以满足一般电桥和谐振器调谐程序的要求，我们计划在未来一年以类似的方式继续该项目。来年，我们计划继续设计、构建、安装和编程用于在正常连续波操作和连续波测量之间切换的新型 240GHz 跟踪连续波源。扫频诊断模式。