Use of whispering-gallery modes for complex permittivity determinations of ultra-low-loss dielectric materials

An Open Resonance Cell for Millimeter Wave Dielectrometer Applications

“…This effect is responsible for that the dielectric loss measurement of the specimen can run into difficulties consisting in that the Q comparison of the empty and rod-loaded ORC structures can yield a negative-valued dielectric loss, which is physically untrue. On the other hand, owing to the increase of the working-mode radiation Q at an optimal choice of the test rod diameter, the radiation loss action on the dielectric parameter measurement nearly vanishes in the given ORC, the same as in an open dielectric resonator [2]. The OR mirror ohmic loss is available from the actual H-component field distribution that can be found by rigorous calculation in terms of the 2-D ORC model.…”

“…Thus, available is a rigorous electrodynamical theory of the ORC like a metaldielectric resonator consisting of a dielectric test rod with infinite metal reflectors on the ends [1]. Owing to a small radiation loss, "whisperinggallery" modes of the ORC like an open dielectric resonator are appropriate for studying dielectrics with minimal absorption [2]. Some theoretical models have been sufficiently developed for dielectric parameter assessment using a spherical-mirror open resonator (OR) with a plane-parallel dielectric layer placed normal to the OR axis [3].…”

Observation of persistent photoconductivity in bulk gallium arsenide and gallium phosphide samples at cryogenic temperatures using the whispering gallery mode method

“…The modes have been labeled N(S)X-m according to Krupka [13] where N or S respectively indicate whether the magnetic field is anti-symmetric or symmetric with respect to the plane of the coupling loops. (The coupling loops are located at the midpoint on the cylindrical wall of the cavity, on opposite sides.)…”

“…[10,11,12] Very low-loss single-crystal materials including sapphire, ruby, Titanium doped sapphire, YAG, Chromium doped YAG, Calcium, Magnesium and Barium Fluoride, quartz, and others have been measured this way. [13,14,15,16,17,18,19,20,21,22] The WGM technique has also been used to characterize the complex permittivity of semiconductors, including bulk monocrystalline Silicon, [23] Gallium Arsenide (GaAs) and Gallium Phosphide (GaP), [24,25] at microwave frequencies from cryogenic temperatures to room temperature.…”

A Modified Formula for Microwave Measurement of Dielectric Loss Using a Closed Cylindrical Cavity Dielectric Resonator

“…The microwave measurements of dielectric properties have recently attracted more and more attention. There are many measurement techniques [4,5], such as Hakki-Coleman end shorted method [6,7], T E 01δ mode dielectric resonator method [8,9], Whispering gallery mode resonators [10][11][12] and Cavity perturbation method [13]. HakkiColeman end shorted method, called parallel plate method, is the most famous resonance technique.…”