A computationally efficient full-wave technique is developed to analyze superconducting microstrip lines on M-plane sapphire in which the optical axis is in the plane of the substrate at an arbitrary angle with respect to the propagation direction. To increase the efficiency of the method, the superconducting strip is replaced by an equivalent surface impedance which accounts for the loss and kinetic inductance of the superconductor. The complex propagation constant and characteristic impedance are calculated. The calculated results show good agreement with previously published data and with the results of the more rigorous volume-integral-equation method. >

A computationally efficient full-wave technique is developed to analyze superconducting microstrip lines on M-plane sapphire in which the optical axis is in the plane of the substrate at an arbitrary angle with respect to the propagation direction. To increase the efficiency of the method, the superconducting strip is replaced by an equivalent surface impedance which accounts for the loss and kinetic inductance of the superconductor. The complex propagation constant and characteristic impedance are calculated. The calculated results show good agreement with previously published data and with the results of the more rigorous volume-integral-equation method.<>

In this paper, the finite-difference time-domain method with nonuniform grid is applied to the analysis of novel three-dimensional (3-D) multichip module (MCM) interconnects. The vertical interconnects involved in this technology consist of small plated via holes defined by a photo lithography system. The via dimensions are in the same order as the microstrip and stripline linewidths to reduce the transmission line discontinuities. Two 3-D transitions are investigated: 1) microstrip-via-stripline and 2) microstrip-via-90-degrees stripline. Electric field distributions and pulse propagation under the microstrip and the stripline are presented. The scattering parameters for various cases are calculated and compared. Geometrical effects such as different conductor extensions on top of the vias and different hole sizes in the reference plane are also investigated. It is found that the 90-degrees bend structure shows less reflection than the straight one. Designers may introduce such 90-degrees bends intentionally to improve signal transmission.

A full-wave spectral-domain volume-integral-equation technique is used to calculate the complex propagation constant, the complex characteristic impedance, and the current distribution for Nb and YBa/sub 2/Cu/sub 3/O/sub 7-x/ microstrip lines and coplanar waveguides with superconducting ground planes. Measurements of resonant frequency and quality factor are performed on Nb microstrip and coplanar waveguide resonators, and the results are compared with numerical calculations. The power-handling capability of various superconducting transmission-line structures is calculated. Results of phase noise measurements on Nb microstrip resonators suggest that phase noise may be related to the current distribution in the structure.<>

The use of the Ginzburg-Landau (GL) theory to predict the nonlinear behavior in a superconducting stripline resonator as a function of input current is reported. A method for calculating the nonlinear inductance and the fractional change in the resonant frequency ( Delta f/f) of a stripline resonator is presented. By solving the GL equations inside the superconducting strip, the spatial variation of the number density of superconducting electrons and, hence, the spatial variation of the magnetic penetration depth are obtained for different values of input current. First, an infinite parallel plate transmission line is considered where the one-dimensional GL equations are solved. The two-dimensional case of a stripline is then considered. Nonlinear inductances are calculated as functions of input current for different superconducting striplines. Comparisons of the calculated Delta f/f with measurements for YBa/sub 2/Cu/sub 3/O/sub 7-x/ stripline resonators show excellent agreement.< >

The Ginzburg-Landau theory is used to predict the nonlinear behavior in superconducting strip transmission lines. A method for calculating the nonlinear inductance and the fractional change in the resonant frequency of a stripline resonator is presented. Comparisons with measurements for two YBa/sub 2/Cu/sub 3/O/sub 7-x/ stripline resonators show excellent agreement.<>

A full-wave numerical analysis is applied to accurately characterize superconducting transmission lines embedded in a layered dielectric medium. A volume integral equation formulation is developed by using a spectral domain dyadic Green's function for stratified media. Galerkin's method with rooftop basis functions for the electric field distribution inside the superconductor is then employed to solve the complex propagation constant. The thickness of the superconducting film is arbitrary in this analysis, and the formulation rigorously accounts for the anisotropy of the superconducting film. The propagation characteristics of a superconducting microstrip transmission line with a thin dielectric buffer layer are investigated. A superconducting stripline configuration with an air gap is also studied.<>

We present measurements of surface impedanceZ S as a function of frequency, temperature, and rf magnetic field for high-quality epitaxial YBa2Cu3O7−x thin films using a striplineresonator technique that measures theQ of the resonator vs. input power. The results have been modeled using Ginzburg-Landau theory at moderate fields, and the Bean critical state model at high fields. Good agreement has been obtained between the model and the measurements. We also discuss the current distributions in the stripline for both low power whenZ S is linear and high power whenZ S is nonlinear.

A method for the transient analysis of frequency-dependent interconnections and planar circuits terminated with nonlinear loads is presented. The frequency-dependent portion of the system is first analysed to obtain the S-parameters and hence the impulse responses. Two different methods are used to get the scattering parameters: the three-dimensional finite-difference time-domain method and an analytical procedure. The nonlinear convolution equations governing the overall system are then derived and solved numerically. The transient responses of a pair of coupled dispersive microstrip lines, a corner discontinuity, and a microstrip switching circuit are presented

A spectral-domain dyadic Green’s function formulation defining the fields in a multilayer chiral medium resulting from the arbitrary distribution of sources is presented. The constitutive parameters and the chirality of each layer are assumed to be different. The fields are obtained in terms of electric- and magnetic-type dyadic Green’s functions. The singular behavior of these dyadic Green’s functions in the source region is taken into account by extracting the delta function singularities. The fields in any layer are obtained in terms of the appropriately defined global reflection and transmission matrices.

A method for the calculation of the current distribution, resistance, and inductance for superconducting strip transmission lines is presented. These calculations allow accurate characterization of both high-T/sub c/ and low-T/sub c/ superconducting strip transmission lines. For a stripline geometry the current distribution, resistance, and inductance are calculated as a function of the penetration depth for various film thicknesses. These calculations are then used to determine the penetration depth for YBa/sub 2/Cu/sub 3/O/sub 7-x/ superconducting thin film from the measured temperature dependence of the resonant frequency of a stripline resonator. The power dependence of the YBa/sub 2/Cu/sub 3/O/sub 7-x/ surface resistance is plotted against the RF magnetic field, which is determined from the calculated current distribution.<>

We report measurements of the surface impedance, Z(S), of YBa2Cu3O7-x thin films using a stripline resonator. The films were deposited on LaAlO3 substrates by off-axis magnetron sputtering. We obtained Z(S) as a function of frequency from 1.5 to 20 GHz, as a function of temperature from 4 K to the transition temperature (approximately 90 K), and as a function of the RF magnetic field from zero to 300 Oe. At low temperatures the surface resistance, R(S), of the films shows a very weak dependence on the magnetic field up to 225 to 250 Oe. At 77 K, R(S) is proportional to the square of the field. The penetration depth shows a much weaker dependence on the field than does R(S). At 1.5 GHz the surface resistance of the best films is 2 x 10(-6) OMEGA at 4 K and 8 x 10(-6) OMEGA at 77 K. We also discuss the origins of the magnetic field dependence of Z(S).

A report is presented on measurements of the surface impedance, Z/sub S/, of YBa/sub 2/Cu/sub 3/O/sub 7-x/ thin films using a stripline resonator. The films were deposited on LaAlO/sub 3/ substrates by off-axis magnetron sputtering. The authors obtained Z/sub S/ as a function of frequency from 1.5 to 20 GHz, as a function of temperature from 4 K to the transition temperature ( approximately 90 K),...

Rate and thermodynamic parameters have been obtained for the protonation reactions of the aromatic amino acidl-tryptophan using a chemical relaxation technique. These have been compared with values obtained for other aliphatic amino acids. It is shown that the proton rate parameters decrease with increasing pH. This might have biological significance.

A general spectral domain formulation to the problem of radiation of arbitrary distribution of sources embedded in a horizontally stratified arbitrarily magnetized linear plasma is presented. The fields are obtained in terms of electric and magnetic type dyadic Green's functions. The formulation is considerably simplified by using the kDB system of coordinates in conjunction with the Fourier transform. The distributional singular behavior of the various dyadic Green's functions in the source region is investigated and taken into account by extracting the delta function singularities. Finally, the fields in any arbitrary layer are obtained in terms of appropriately defined global upward and downward reflection and transmission matrices.

In this paper, full modal analysis is used to study the dispersion characteristics of microstrip lines periodically loaded with crossing strips in a stratified uniaxially anisotropic medium. Dyadic Green's functions in the spectral domain for the multilayered medium in conjunction with the vector Fourier transform (VFT) are used to formulate a coupled set of vector integral equations for the current distribution on the signal line and the crossing strips. Galerkin's procedure is applied to derive the eigenvalue equation for the propagation constant. The effect of anisotropy for both open and shielded structures on the stopband properties is investigated.

The radiation from a cylindrical microstrip antenna excited by a probe is analyzed. Both the cylindrical-rectangular and the wraparound elements are discussed. The current distribution on the patch is rigorously formulated using a cylindrically stratified medium approach. A set of vector integral equations is derived which governs the current distribution on the patch. The set of equations is then solved using a moment method. The input impedance and the radiation pattern are derived both exactly and in the small substrate thickness limit.