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Acoustic filters are, without any doubt, the key technology for the development of highly miniature high performance RF/Microwave filters. Such a technological and engineering effort has been one of the driving forces for the expansion of handset wireless devices, such as smart phones, tablets and other portable gadgets (integrating +50 filters each of those portable devices). The main features of current acoustic wave (AW) filters: low insertion loss, sharp frequency response and highly miniaturized, in comparison with other technologies, are highly desirable in RF components for space applications.

We discuss an harmonic balance algorithm to analyze High Temperature Superconducting (HTS) circuits subject to wideband signals, such as the ones used in CDMA wireless systems. Undersampling is used to discretize and down-convert the bandpass signal resulting from the weak HTS nonlinearities, and this has to be taken into account when performing time-domain calculations of the nonlinear effects. We present an overview of the algorithm and describe an example to verify the software developed. We also discuss a tentative performance assessment of an HTS preselect filter in a UMTS base station receiver

This article describes a procedure for the calculation of the intermodulation behavior of the TM010 mode in high temperature superconducting (HTS) disk resonators from a description of the local HTS nonlinearities. Successful cross-checks are performed by comparing the theoretical results with experimental measurements and simulations based on the multiport harmonic balance algorithm for a specific model of HTS nonlinearity. The application of this procedure to the determination of nonlinear material parameters from disk resonator measurements is illustrated and compared to theoretical predictions.

This work describes an alternative to the traditional dielectric resonator topology used for measuring surface impedance in High Temperature Superconducting (HTS) films. A gap is introduced above the dielectric so that only the lower film is in direct contact with it. This arrangement has been used extensively for mechanical tuning of dielectric resonators and, when used for surface impedance measurement, it can be designed to make the losses in the upper film small relative to the overall resonator losses. Then, measured results are mostly due to one of the films and not the average of two. The specifics of a resonator design for measuring 2-inch wafers are presented. An analysis and optimization of the resonator is done using a numerically efficient mode-matching algorithm.

We report on the growth of epitaxial YBa2Cu3O7 thin films on X-cut LiNbO3 single crystals. The use of double CeO2/YSZ buffer layers allows a single in-plane orientation of YBa2Cu3O7, and results in superior superconducting properties. In particular, surface resistance Rs values of 1.4 m have been measured at 8 GHz and 65 K. The attainment of such low values of Rs constitutes a key step toward the incorporation of high Tc materials as electrodes in photonic and acoustic devices.

This paper describes the application of Harmonic Balance algorithms to predict nonlinear effects in planar High Temperature Superconductors (HTS) microwave circuits. The resulting algorithms are fast and efficient and can be used both for the characterization of the nonlinearities in the HTS material, and for the prediction of the behavior of an HTS circuit given the parameters of these nonlinearities (such as a dependence of the surface impedance on the current density). Most previously published nonlinear HTS models can be used, because the algorithms are not restricted to a specific model of HTS nonlinearities. Two different types of algorithms are described: (1) algorithms specific for one-dimensional resonators (transmission lines and TM010 disk resonators) and (2) an algorithm based on the combination of Method of Moments and Harmonic Balance, applicable to 2D planar structures with few restrictions in their shape. Several cross-checks with theory and measurements are presented.

This work presents a very compact duplexer based on novel miniaturized loaded-close-loop dual resonators. Two different dual resonators are used to establish the two bands, corresponding to the transmitter and the receiver bands. The two filters are connected to the antenna through a matching network. We have fabricated a prototype using a 10.2 dielectric constant substrate. The duplexer fits in a 16 /spl times/ 10 mm/sup 2/ area and has less than 2dB insertion loss and more than 20 db of isolation. Measurement results are in good agreement with the simulation

This work describes and compares two alternative methods of analyzing dielectric-loaded cavities for measurement of intermodulation distortion in HTS films. One of them is based on assuming a specific type of HTS nonlinearities and developing theoretical equations based on them. The second is based on a numerical approach that can be applied to many types of nonlinearities. Both methods are shown to work on measured data of representative HTS films.