Open nonradiative cavities as millimeter wave single-mode resonators

Abstract

Open single-mode metallic cavities operating in nonradiative configurations are proposed and demonstrated. Starting from well-known dielectric resonators, possible nonradiative cavities have been established; their behavior on the fundamental TE 011 mode has been predicted on the basis of general considerations. As a result, very efficient confinement properties are expected for a wide variety of open structures having rotational invariance. Test cavities realized having in mind practical millimeter wave constraints have been characterized at microwave frequencies. The field distribution of some relevant configurations has been modeled by means of a finite-element numerical method. The obtained results confirm the expected high performances on widely open configurations. A possible excitation of the proposed resonators exploiting their nonradiative character is discussed, and the resulting overall ease of realization enlightened in view of millimeter wave employments. _______________ @

High-frequency EPR applications of open nonradiative resonators

“…In this device, the limiting height of the aperture is k 0 2 , with k 0 the resonant wavelength, whereas the overall size of the resonator is of the order of k 0 [31]. Hence, this resonator combines the minimum active volume typical of a single-mode cavity with a largely open structure resembling a Fabry-Perot resonator.…”

High frequency single-mode resonators for EPR spectroscopy enabling rotations of the sample about two orthogonal axes

“…It represents in fact a natural development of the NR waveguide first proposed [17,18]. The radiation can be stored in the central region of this structure since the dielectric material increases the optical distance between the metallic plates [12,14]. The TE 011 mode of this resonator shows the typical magnetic dipole field distribution, in which the maximum magnetic fieldB l lies in the center of the resonator and is directed along its axis, as shown in Fig.…”

“…The fundamental question concerns the effect of the sample holder on the electromagnetic properties of the resonator. The new configuration loses indeed the rotational invariance, which was the crucial point in the prediction of a proper NR resonant behaviour [14]. Moreover, for practical millimeter wave applications the diameter of the sample holder cannot be much smaller than the size of the resonator.…”

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

“…The same principle has been extended to metallic resonators, allowing the realization of a widely open TE 011 cavity. 15 In this reference the possibility of open resonators which combine the benefits of both metallic cavities and dielectric resonators was anticipated. The present article is a further step along this research line, in which the concept of NR resonator is generalized in order to include axially open configurations.…”