Circulating power, RF magnetic field, and RF current density of shielded dielectric resonators for power handling analysis of high-temperature superconducting thin films of arbitrary thickness

Abstract

In the current quest for HTS films with negligible power effects at high RF power levels for wireless communications, accurate calculations of a maximum RF magnetic field H max and of a maximum RF current density J max flowing on the surface of superconducting films is necessary to allow for any sensible conclusions and comparisons. As the dielectric resonator method is used most frequently for investigation of HTS losses, the authors discuss in this paper a dependence of the circulating power and of a maximum RF magnetic field H max on dielectric resonators' geometry as well as of the maximum RF current density J max flowing on the surface of superconducting films on the films' thickness, for a general case of a resonator shielded in a metallic cavity. The authors' results demonstrate that under the same input power levels the same HTS films may be exposed to differing RF power level conditions, depending on the cavity to dielectric radius ratio and thickness of superconducting films. This means that there may be a significant discrepancy between calculated and real power handling capabilities of HTS films tested in different dielectric resonators unless correct formulas are used.

Analysis of dielectric-loaded cavities for characterization of the nonlinear properties of high temperature superconductors

“…CAVITY ANALYSIS The cavity used ( Fig. 1) is similar to the ones used for surface resistance ( ) measurements of HTS films [6], [7]. However, unlike in measurements, one of the endplates in our cavity may be a normal metal since it is not required that the HTS losses dominate the overall cavity loss.…”

“…where is the radial dependence of the surface current of the mode, i.e., [7]: (4) where is the -direction propagation constant, and are the -direction wavenumbers (inside and outside the dielectric respectively), , being , , , , , , the corresponding Bessel and Hankel functions. The electric field on the HTS film can be found using (3) and (4) in (2): (5) where .…”

STUDY OF THE ELECTRODYNAMIC RESPONSE OF MgB2 SINTERED PELLETS AND THIN FILMS

“…The maximum in the radial component of the magnetic field is reached in the cavity around a circle of radius of about 2 mm. The application of formula (7) to our case (D/d < 1.5) gives a relative error in the evaluation of H max below 5% [35].…”

Comparison between nonlinear measurements in patterned and unpatterned thin films

“…In these conditions, the surface current density of the HTS endplate in an intermodulation experiment can be written as j s (ρ, t) = ( j s,1 cos ω 1 t + j s,2 cos ω 2 t) f (ρ)φ, whereφ is the unit vector in the azimuthal direction and f (ρ) describes the radial dependence of the TE 011 mode (see [10] for a detailed expression). Reference [8] shows the steps to find the parameter α to be used in (4):…”

“…where R is the ratio of the energy stored outside the dielectric rod to that stored inside, and can be written as [10]:…”