The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
D. J. Scalapino - One of the best experts on this subject based on the ideXlab platform.
-
Phenomenological Theory of Intermodulation in HTS Resonators and Filters
Journal of Superconductivity, 1999Co-Authors: T. Dahm, D. J. Scalapino, B. A. WillemsenAbstract:Recent work on nonlinear effects in microwave resonators and filters from high temperature superconductors, focusing on Intermodulations, is reviewed. We calculate the intrinsic nonlinear response of s -wave and d -wave superconductors. A phenomenological description of the lowest order nonlinear behavior in high- T _c films in terms of a single parameter, j _IMD, is proposed. We show how this description can be used to calculate the Intermodulation power arising in realistic microstrip resonators. These calculations show good agreement with measurements on hairpin resonators. This description can also be used for the modeling of nonlinear behavior of complex microwave filters.
-
microwave Intermodulation in thin film high tc superconducting microstrip hairpin resonators experiment and theory
Applied Physics Letters, 1997Co-Authors: B. A. Willemsen, Thomas Dahm, D. J. ScalapinoAbstract:We present experimental results for microwave Intermodulation in a series of superconducting hairpin resonators. We find that geometry plays a dominant role in determining both the losses and Intermodulation in these resonators. The experimental data can be reproduced using recent theoretical calculations with a single parameter, JIMD (77 K). We compare the response of the fundamental and the first harmonic modes of these resonators to find that the use of the first harmonic mode gives less Intermodulation, but we also find higher losses due to the more extended fields of this mode.
D Raboso - One of the best experts on this subject based on the ideXlab platform.
-
experimental analysis of passive Intermodulation at waveguide flange bolted connections
IEEE Transactions on Microwave Theory and Techniques, 2007Co-Authors: C Vicente, D Wolk, H L Hartnagel, B Gimeno, Vicente E Boria, D RabosoAbstract:In this paper, the generation of passive Intermodulation at rectangular waveguide flange bolted connections is investigated. An exhaustive series of tests has been performed in order to provide understanding on the physics lying behind such a phenomenon. In particular, the Intermodulation response of the system has been studied as a function of the applied torque to the flange screws. It has been found that, in some situations, the Intermodulation response differs from its expected behavior. An interpretation of such discrepancies is given, and practical guidelines for the design of waveguide flanges free of passive Intermodulation are provided as well
B. A. Willemsen - One of the best experts on this subject based on the ideXlab platform.
-
Phenomenological Theory of Intermodulation in HTS Resonators and Filters
Journal of Superconductivity, 1999Co-Authors: T. Dahm, D. J. Scalapino, B. A. WillemsenAbstract:Recent work on nonlinear effects in microwave resonators and filters from high temperature superconductors, focusing on Intermodulations, is reviewed. We calculate the intrinsic nonlinear response of s -wave and d -wave superconductors. A phenomenological description of the lowest order nonlinear behavior in high- T _c films in terms of a single parameter, j _IMD, is proposed. We show how this description can be used to calculate the Intermodulation power arising in realistic microstrip resonators. These calculations show good agreement with measurements on hairpin resonators. This description can also be used for the modeling of nonlinear behavior of complex microwave filters.
-
microwave Intermodulation in thin film high tc superconducting microstrip hairpin resonators experiment and theory
Applied Physics Letters, 1997Co-Authors: B. A. Willemsen, Thomas Dahm, D. J. ScalapinoAbstract:We present experimental results for microwave Intermodulation in a series of superconducting hairpin resonators. We find that geometry plays a dominant role in determining both the losses and Intermodulation in these resonators. The experimental data can be reproduced using recent theoretical calculations with a single parameter, JIMD (77 K). We compare the response of the fundamental and the first harmonic modes of these resonators to find that the use of the first harmonic mode gives less Intermodulation, but we also find higher losses due to the more extended fields of this mode.
Mario Huemer - One of the best experts on this subject based on the ideXlab platform.
-
The influence of DC offsets on the digital cancellation of second-order TX Intermodulation distortions in homodyne receivers
2012 IEEE International Conference on Wireless Information Technology and Systems (ICWITS), 2012Co-Authors: Christian Lederer, Mario HuemerAbstract:Intermodulation distortions are produced when a modulated blocker signal with a nonconstant envelope gets processed by a stage with a nonlinear characteristic. Especially in homodyne receivers (RX), where the RX signal is directly downconverted into the baseband, even-order Intermodulations might overlap the wanted signal in its baseband. In Frequency Division Duplex (FDD) systems, where RX and transmitter (TX) are active at the same time, the own TX is the source of major Intermodulation distortions, since the TX signal power can be 130dB larger than that of the RX signal [1]. Usually the isolation of the duplexers, which are used to seperate TX and RX path at the antenna, is limited. As a consequence parts of the TX signal are leaking into the RX path. Due to nonlinearities, especially of the downconverter, Intermodulation distortions are produced, degrading the performance of the RX. The quadratic term in the transfer functions of those nonlinear stages produces the major distortions, the so called second-order Intermodulation distortions (IMD2). One approach to avoid IMD2 is to attenuate the TX leakage before the downconversion in the RX takes place. This would require analog filters which cannot be integrated into the radio frequency (RF) transceiver chip, increasing the production costs of the wireless communication device. Furthermore, in multiband RX, separate bandpass filters are needed for different signal bands.
-
LMS based digital cancellation of second-order TX Intermodulation products in homodyne receivers
2011 IEEE Radio and Wireless Symposium, 2011Co-Authors: Christian Lederer, Mario HuemerAbstract:Second-order Intermodulation products are produced by non-linearities in the transfer functions of the receiver's signal processing blocks. Especially in homodyne receivers the second-order Intermodulations are problematic since they are convolved into baseband and overlap the wanted signal. In this paper a Least-Mean-Square (LMS) adaptive filter approach to estimate and cancel the transmitter (TX) induced second-order Intermodulation distortion (IMD2) in the digital domain is presented. The performance of the proposed cancellation method and its dependency on the number of used filter coefficients is verified on measured data of the digital front end (DFE) output of an UMTS transceiver chip.
Heikki Seppa - One of the best experts on this subject based on the ideXlab platform.
-
Intermodulation read out principle for passive wireless sensors
IEEE Transactions on Microwave Theory and Techniques, 2011Co-Authors: Ville Viikari, Heikki SeppaAbstract:This paper presents a general Intermodulation read-out principle for passive wireless sensors. A sensor utilizes a mixing element, such as a varactor, and it can be equipped with a capacitive, inductive, or resistive sensor element. When the sensor is illuminated with signals with two frequencies, it replies the sensor data at an Intermodulation frequency. An analytical expression for the Intermodulation response of the sensor is derived and verified by simulations. The concept is demonstrated at 1.2 GHz.
