MODELING OF A CAVITY BASED ON A PROFILED SAPPHIRE DISC

Abstract

Sapphire dielectric resonator (SDR) used in the lownoise microwave oscillators for increasing Q oscillating system usually have the form of a smooth cylinder or disc inside the coaxial metallic screen. Since the high-Q have only the higher azimuthal modes of SDRs, there are many additional resonances in the vicinity of the selected mode that can disrupt the normal operation of the generator. It is believed that if you remove the dielectric from the regions of the weak field of the selected type fluctuations, such a change in the disc shape slightly affect the planned fluctuation, while significantly affecting the disturbing fashion. Described transformation, hereinafter called profiling cylindrical surface, does not destroy the structure of the field operating mode. Simultaneously hamper modes having different azimuthal indices resulting from withdrawal of the disc material periodic uneven structure markedly shifts the resonance frequency and generates additional diffraction losses. In this paper, for the first time we considered the possibility of expanding the spectrum hamper modes near SDR prescribed frequency by replacing a smooth cylindrical wall of some SDR periodically profiled surface. Accounting for the specifics of the field structure in the smooth disk and additional considerations associated with sapphire processing technology, lead to the conclusion that should be used for testing of the proposed profiling method with the cylindrical wall SDR circles. When performing calculations we record the frequency and the quality factor corresponding picture field HE6 and the nearest frequency of the hamper mode on the left and right of the base resonance for different values of the disc format. Changing the format performed a variation of the height of the sapphire core. Managing the process was carried out more specialized software that automates record the results and launchs the calculation in the program CST Microwave Studio. Considered examples show that the above method of loose hamper vibrations near the planned mode frequency of SDRs by the profiling of the cylindrical surface can be very effective when properly selecting the profiling parameters.