Four calculation techniques for the Q-factor determination of resonant structures are compared on the basis of the influence of the VNA measurement uncertainty. The influence is evaluated using Monte Carlo calculations. On the basis of the deviation, the dispersion, and the effect of nearby resonances, the circle fitting method is the most appropriate technique. Although the 3dB method is the most popular technique, the Q-factors calculated by this method exhibit deviations, and the sign and amount of the deviation depend on the measurement setup. Comparisons using measurement data demonstrate that the uncertainty of the dielectric loss tangent calculated by the circle fitting method is less than a third of those calculated by the other three techniques.

This paper presents an innovative fabrication process for a planar circuits at millimeter-wave frequency. Screen printing technology provides low cost and high performance coplanar waveguides (CPW) lines in planar devices operated at millimeter-wave frequency up to 110GHz. Printed transmission lines provide low insertion losses of 0.30dB/mm at 110GHz and small return loss like as impedance standard lines. In the paper, Multiline Thru-Reflect-Line (TRL) calibration was also demonstrated by using the impedance standard substrates (ISS) fabricated by screen printing. Regarding calibration capability validation, verification devices were measured and compare the results to the result obtained by the TRL calibration using commercial ISS. The comparison results obtained by calibration of screen printing ISS are almost the same as results measured based on conventional ISS technology.

We have studied the effect of Ga and Ca substitution in the PrBa2Cu3Oδ (PBCO) barrier on the parameters of high-temperature-superconductor ramp-edge Josephson junctions. Pr 1-XCa XBa2Cu3Oδ (X=0. 15, 0. 3) had reduced bulk barrier resistivity as small as 10 mΩcm which was close to the metal-insulator transition. Also, PrBa2Cu 3-ZGa ZOδ, written as GaZ-doped PBCO (Z=0. 15, 0. 3, 0. 6), had enhanced resistivity neater than 1 kΩcm at 4. 2 K. The transport mechanisms in these bulk barriers fitted well with the Mott variable hopping model. The critical current density Jc and normalized junction conductance (R nA)-1 decayed exponentially with almost the same decay length, as the barrier thickness increased. The decay length depended on the barrier material, and ranged from 1. 7 nm to 6. 5 nm for Jc, from 1. 9 nm to 7. 2 nm for (Rn A)-1. Because on these experimental results, we conclude that direct tunneling is the dominant transport mechanism for both quasi particles and paired particles in our junctions, while resonant tunneling should be considered as an additional transport mechanism of these two kinds of particles in the junctions with the PBCO-based barriers reported so far. It was also found that Ga doping raised the characteristic voltage Vc while Ca doping reduced it, though the Vc values obtained here were still small compared to the theoretically predicted values. The spacewise metal insulator transition at the interfaces caused by a high density of localized states in the barriers seemed to be responsible for the reduction in Vc. The best Vc value was 0. 32 mV at 77 K and 5. 2 mV at 4. 2 K using a Ga0. 6-PBCO barrier. These Vc values are suitable for electronics applications. Furthermore, superconducting-gap-like structures were observed in the junctions with highly resistive Ga-doped PBCO barriers.

The deposition conditions of Y0.9Ba1.9La0.2Cu3Oy (La-YBCO) and (LaAlO3)0.3-(SrAl0.5Ta0.5O3)0.7 (LSAT) thin films were studied with the aim of fabricating ramp-edge Josephson junctions on a superconducting ground plane. These films were deposited by a magnetron sputtering method and utilized as a base electrode and an insulating layer under the electrode, respectively. YBa2Cu3Oy thick films grown by liquid phase epitaxy (LPE-YBCO) were used for a ground plane. Insertion of a SrTiO3 buffer layer between LSAT and LPE-YBCO significantly improved the flatness of the film surface. La-YBCO films with a flat surface and Tc (zero) of 87K were reproducibly obtained by DC sputtering. We have fabricated ramp-edge Josephson junctions using these films. Resistively and capacitively shunted junction (RCSJ)-like characteristics were observed in them. An Ic spread of 10.2% (at 4.2K, average Ic = 0.5 mA) was obtained for a 1000-junction series-array.