Hartnett John G, Tobar Michael E, Ivanov Eugene N, Luiten Andre N
IEEE Trans Ultrason Ferroelectr Freq Control. 2013 Jun;60(6):1041-7. doi: 10.1109/TUFFC.2013.2668.
A process for optimal design of a room-temperature whispering-gallery-mode sapphire resonator has been developed. In particular, design rules were determined to enable choice of the optimum azimuthal mode number and resonator radius for a given resonance frequency. The coupling probe design was investigated and it was found that straight antenna probes aligned radially and positioned in the mid-plane of the resonator gave the highest unloaded Q-factors because of minimized probe losses. We noted that when coupling through this technique (as compared with a perpendicularly positioned probe) the mode standing wave pattern would lock to some asymmetry in the crystal resonator itself and not to the probe. This was confirmed by noting that the coupling could be altered over a significant range by merely rotating the resonator. Following these optimal design rules, we were able to measure the Q-factors of quasi-TE and quasi-TM modes with high precision in four cylindrical sapphire resonators at room temperature. From this analysis, the highest attainable Q-factor is expected to be (2.1 ± 0.1) x 10(5) at 9 GHz in a quasi-TM mode.
已开发出一种用于室温回音壁模式蓝宝石谐振器的优化设计方法。具体而言，确定了设计规则，以便为给定的共振频率选择最佳方位模数和谐振器半径。对耦合探针设计进行了研究，发现径向对齐并位于谐振器中平面的直天线探针由于探针损耗最小而具有最高的无载品质因数。我们注意到，当通过这种技术进行耦合时（与垂直放置的探针相比），模式驻波图案会锁定到晶体谐振器本身的某些不对称性上，而不是探针上。通过注意到仅通过旋转谐振器就可以在很大范围内改变耦合，这一点得到了证实。遵循这些优化设计规则，我们能够在室温下在四个圆柱形蓝宝石谐振器中高精度地测量准TE和准TM模式的品质因数。根据该分析，在9 GHz的准TM模式下，预计可达到的最高品质因数为(2.1 ± 0.1) x 10(5)。
