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 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

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),...

The performance of a microstrip hammerhead filter that has been fabricated on an electrically thin layer of semiinsulating GaAs backed by a fused quartz substrate was measured and compared to results of a three-dimensional finite-difference time-domain (FD-TD) program used to calculate the response of the filter both with and without the GaAs layer. The program, presented by D.M. Sheen et al. (IEEE Trans. Microwave Theory and Techniques, vol.38, no.7, p.849-57, 1990), discretizes the entire structure and then simulates the propagation of a Gaussian pulse through the filter. The microstrip filter is intended for applications involving ultra-thin lifted-off or etched-back GaAs containing both active devices and passive microstrip circuitry backed by a much thicker mechanically rigid low-loss, low-dielectric-constant substrate. The low-pass characteristics of the hammerhead filter with the intermediate GaAs layer are compared with those of the same filter on quartz alone. Both the measured and computed data show a significant shift in cutoff frequency ( approximately=10% at the 3 dB points) for a GaAs layer that is 0.007 wavelengths thick at 4 GHz.<>

A direct three-dimensional finite-difference time-domain (FDTD) method is applied to the full-wave analysis of various microstrip structures. The method is shown to be an efficient tool for modeling complicated microstrip circuit components and microstrip antennas. From the time-domain results the input impedance of a line-fed rectangular patch antenna and the frequency-dependent scattering parame...