A Basic Study on a Resonance Characteristics of the Whispering Gallery Mode on a Layered Dielectric Disks Resonator

本文的研究课题是将回音壁模式的层状介质圆片谐振器应用于毫米波带通滤波器。上（下）盘与下（上）盘之间隔开一个气隙长度d。2001年，我们从微波区的实验中得出结论，上述结构适用于带通滤波器。2002年，我们的研究取得了进展。也就是说，我们可以估计耦合的两个介质盘之间的耦合系数和外部Q值从滤波器的设计理论。通过研究发现，只要给定中心频率和带宽，就可以实现所需的带通滤波器。在电磁理论中，我们使用了一个近似的分离变量的方法，这已经提出了由本研究的首席研究员，计算耦合的两个介质盘的耦合系数。从这些检查中，我们可以确定气隙长度d和从盘到用于激励盘的矩形介质波导的距离s。我们还进行了实验，以确认我们的分析的有用性和充分性，在毫米波波段。由于回音壁模式谐振器具有多个谐振频率，在上述结构中，在期望的带通宽度附近存在寄生带通宽度。然后，我们提出了另一种类型的结构来抑制寄生带通宽度。在新结构中，用与上（下）盘不同的盘代替气隙。实验证实，这种新结构抑制了约20dB的杂散带通强度。（参见下页第一条）

A subject of our research is to apply a layered dielectric disks resonator operated by Whispering Gallery Modes to a band pass filter in millimeter wave band. Upper (lower) disk is separated from lower (upper) one by an air gap length d.In 2001, we concluded from experiments in microwave region that the above stated structure was applicable to the band pass filter. In 2002, we had been progressing in our research. Namely, we could estimate a coupling coefficient between coupled two dielectric disks and external Q value from a design theory for filter. It was found from our investigations that we could realize a desired band pass filter by giving a center frequency and band width. In electromagnetic theory, we used an approximated separation variables method, which had been proposed by the head investigator of this research, to calculate the coupling coefficient of coupled two dielectric disks. From these examination, we could decide the air gap length d and a distance s from the disk to a rectangular dielectric waveguide which was used to excite the disk. We had also performed experiments to confirm our analytical usefulness and adequacy in millimeter wave band. A part of this Grant-in-Aid for Scientific Research was spent on a millimeter wave source module which was used in these experiments.As the whispering gallery modes resonator has many resonance frequencies, spurious band pass widths exist near the desired band pass width in the above stated structure. Then, we proposed another type of structure to suppress the spurious band pass widths. In new structure, different disks from the upper (lower) disk were substituted for the air gap. We confirmed experimentally that the new structure suppresses the spurious band pass strength about 20dB. ( Refer the first article in next page)