Axially open nonradiative structures: An example of single-mode resonator based on the sample holder

Abstract

The concept of nonradiative dielectric resonator is generalized in order to include axially open configurations having rotational invariance. The resulting additional nonradiative conditions are established for the different resonance modes on the basis of their azimuthal modal index. An approximate chart of the allowed dielectric and geometrical parameters for the TE 011 mode is given. A practical realization of the proposed device based on commercial fused quartz tubes is demonstrated at millimeter wavelengths, together with simple excitation and tuning mechanisms. The observed resonances are characterized in their basic parameters, as well as in the field distribution by means of a finite element method. The predictions of the theoretical analysis are well confirmed, both in the general behaviour and in the expected quality factors. The resulting device, in which the sample holder acts itself as single-mode resonating element, combines an extreme ease of realization with state-of-the-art performances. The general benefits of the proposed open single-mode resonators are finally discussed.

High-frequency EPR applications of open nonradiative resonators

“…The presence of the slits compromises significantly the merit factor, which is reduced to approximately Q 0 = 5000 or less [4,12,22], hence lower than the values obtained with the NR resonator described in this paper. It is worthwhile to note that lower quality factors, but better conversion factors, can be obtained with dielectric NR resonators [47].…”

Quantitative cw Overhauser effect dynamic nuclear polarization for the analysis of local water dynamics

“…[36]. The novel non-radiative microwave resonator design presented by Annino et al [37, 38] provides very high ESR performance at 95 GHz, easily integrates DNP functionality, and can be fabricated from commonly available materials. Researchers have also employed ODNP hyperpolarization to enhance perfusion imaging, where the first proof of principle application by Han et al [39] was followed by further development and applications at 10 GHz (ESR) [40–43], an extension to higher frequencies (35 GHz ESR) by Krummenacher et al [44], and a recent in vivo study demonstrating enhanced visualization of brain perfusion in a live rat [45].…”

Properties of trapped electromagnetic modes in coupled waveguides

“…The reflected wave can be decoupled by the incoming one by means of a circulator, before reaching the detector. More details about a similar setup can be found in [24]. The configuration of Fig.…”