Complex Permittivity Measurements at Variable Temperatures of Low Loss Dielectric Substrates Employing Split Post and Single Post Dielectric Resonators

A split post dielectric resonator in a copper enclosure and a single post dielectric resonator in a cavity with superconducting end-plates have been constructed and used for the complex permittivity measurements of single crystal substrates. (La,Sr)(Al,Ta)O3, LaAlO3, MgO and quartz substrates have been measured at temperatures from 20 K to 300 K in the split post resonator and from 15 K to 80 K in the single post resonator. The TE01delta mode resonant frequencies and unloaded Qo-factors of the empty resonators at temperature of 20 K were: 9.952 GHz and 25,000 for the split post resonator and 10.808 GHz and 240,000 for the single post resonator respectively.Comment: 4 pages, 8 figures, 1 tabl

Precise microwave characterization of MgO substrates for HTS circuits with superconducting post dielectric resonator

Accurate data of complex permittivity of dielectric substrates are needed for efficient design of HTS microwave planar circuits. We have tested MgO substrates from three different manufacturing batches using a dielectric resonator with superconducting parts recently developed for precise microwave characterization of laminar dielectrics at cryogenic temperatures. The measurement fixture has been fabricated using a SrLaAlO3 post dielectric resonator with DyBa2Cu3O7 end plates and silver-plated copper sidewalls to achieve the resolution of loss tangent measurements of 2 {\times} 10-6. The tested MgO substrates exhibited the average relative permittivity of 9.63 and tan {\delta} from 3.7 {\times} 10-7 to 2 {\times} 10-5 at frequency of 10.5 GHz in the temperature range from 14 to 80 K.Comment: 6 pages, 8 figures, 3 table

High temperature superconducting films and HTS devices for wireless communication systems

HTS films exhibit very low losses, and HTS microstrip filters ensure a low noise figure and sharp skirts when employed in cellular base station receivers. This paper reviews the current state of the art in the field of microwave applications of superconducting thin films and of problems related to nonlinear power effects in HTS materials

Analysis of high frequency properties of multilayer structures for multichip modules

The microwave surface resistance and reactance of YBa₂Cu₃O₇ multilayers for MCMs have been studied as a function of thickness and relative permittivity of dielectric layers at 500 MHz and 10 GHz propagation frequency. Additionally, frequency properties of a YBCO/CeO₂/SrTiO₃/YBCO/LaAlO₃ multilayer have been analyzed and results compared with measurement results. Performed simulations have shown that a dielectric layer of high relative permittivity, necessary for good isolation between superconducting ground planes and power planes in the multichip modules, has negligible influence on the effective surface resistance and reactance up to 0.5 μm dielectric thickness

Recent advances in measurements of permittivity and dielectric losses at microwave frequencies

The precise microwave characterization of dielectric materials is an important issue for emerging technologies of the 21st century. In this paper recent advances in resonant techniques for permittivity and dielectric loss tangent measurements of low and medium loss dielectrics at microwave frequencies are presented

Temperature dependence of permittivity and loss tangent of Lithium Tantalate at microwave frequencies

Lithium Tantalate exhibits excellent electro-optical, piezoelectric and pyroelectric properties and a very low thermal expansion. In this paper, we report measurements of loss tangent and the real part of the relative permittivity r measured in c-axis LiTaO3 crystals in the temperature range from 14 K to 295 K at a frequency of 11.4 GHz and 10 GHz. Microwave properties of LiTaO3 were determined by measurements of the resonance frequency and the unloaded Qo-factor of a TE011 mode cylindrical cavity containing the sample under test and accounting for uncalibrated cables and adaptors inside the cryocooler. The permittivity of LiTaO3 was found to increase from 38.9 to 41.1 and the loss tangent to change from 1.1×10-4 to 6.5×10-4 over the full temperature range. Due to its low loss and relatively high permittivity Lithium Tantalate is suitable for microwave applications