ULTRA-WIDEBAND 170 AND 240 GHZ CW SOURCE SWEEPING SYSTEMS

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 通常，通过对发射/反射功率的扫频测量，与ESR谱的电桥设置相关的验证和调谐过程大大简化。扫频评估方法在毫米波领域特别有用，当采用准光技术时更是如此，这主要是因为大量的相互作用调整和增强的准光桥对额外路径反射的敏感性。与扫描测量能力一样有用的是，现成的测试和测量仪器即使在较低的毫米波制度下(即低于100 GHz)也提供锁相扫描频率能力，价格高得离谱，而且在该频率范围以上，似乎只有在更昂贵的定制基础上才能获得。出于这个原因，Acert之前没有投资于其170 GHz和250 GHz C.W.的毫米波扫描测量能力。分光计电桥。 去年，Acert为其高场C.W.获得了显著改进的中心频率为170 GHz和240 GHz的毫米波源。准光学ESR光谱仪。这些单元产生的输出功率比以前的C.W.高出约12db。在相对较宽的频率范围(FC？5 GHz)上提供锁相操作。鉴于这些电源提供的输出功率显著较高，为优化感应反射模式下的电桥运行，进行了一项广泛的电桥和谐振器设计升级计划。在这项开发工作的过程中，显然不仅扫频测量能力是必不可少的，而且方便地，这些扩展范围C.W.对于这种偶然的使用，资源可能会被强制投入使用。 到目前为止，我们在这方面的工作已经产生了一个临时的170 GHz扫频系统，它在高频反射电桥的设置和微调中被证明是非常有用的。我们发现，尽管扫描输出功率没有被主动地调平，但源乘法器的级偏置电平可以很容易地调整，以在FC？1.0 GHz处提供优于1.2分贝的平坦度，并且在从165 GHz到175 GHz的整个源跟踪范围内提供大约3dB的平坦度。这一性能水平足以满足一般电桥和谐振器调谐程序的需要。鉴于到目前为止的令人鼓舞的结果，我们计划在来年继续这一项目，对新的240 GHz跟踪C.W.进行类似的研究。扫描测量的来源。在未来一年，我们计划继续设计、建造、安装和编程简化的操作员界面，以便在正常的C.W.之间切换。运行和扫频诊断模式。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. 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.