86,627 research outputs found
L’ORO, IL BIANCO CALCE E LA POLVERE DI MARMO Stucchi e stuccatori nella Vicenza del Palladio
No full textMaxwell's Equations and Potentials in Dirac form using Geometric Algebra
No full textThe basis for engineering electromagnetic computations still relies on Gibbs' vector algebra. It is well known that Clifford algebra (geometric algebra) presents several enhancement on the latter. In this paper it is shown that Maxwell's equations can be cast in a form similar to Dirac equation by using spinors. Additionally, a similar relation is derived for the fields and the potentials. It is also shown that, as a consequence of using the geometric algebra approach, the Lorenz gauge comes naturally from the grade structure
Rigorous modeling of mid-range wireless power transfer systems based on Royer oscillators
No full textResonant Wireless Power Transfer over variable distances requires adaptive frequency change in order to preserve efficiency. The Royer oscillator provides the capability of correctly tracking the most efficient resonant frequency without the need of cumbersome control systems. In this paper, a rigorous modeling, including frequency-dependent losses, of a wireless power transfer system based on Royer oscillators is presented and experimentally verified
Gains Maximization for Two-port WPT Links with Three Coils
No full textIn this paper a two-port network for wireless power transfer realized with three coils is considered. Usually, these networks are analyzed assuming that one of the three mutual couplings is negligible. However, this hypothesis is not always applicable, there are specific configurations for which no coupling can be neglected. Accordingly, in this paper the optimal terminating impedances are derived for the general case where all the couplings are taken into account. The performance of the network are described by using the three power gains (available, power, transducer gains). Analytical formulas and circuital simulations are reported and discussed
Fast and robust inexact Newton approach to the harmonic-balance analysis of nonlinear microwave circuits
No full textThe letter discusses a novel approach to nonlinear microwave circuit simulation by the harmonic-balance (HB) technique. The nonlinear system is solved by an inexact Newton method, and the GMRES iteration is used at each step to find a suitable inexact Newton update. The peculiar structure of the Jacobian matrix allows the basis vectors of the Krylov subspace to be computed mostly by the FFT. The resulting simulation tool is fast and robust, and outperforms conventional HB techniques when applied to large-size nonlinear analysis problems
On the Use of Matching Networks and Relays for Maximizing the Gains of IR WPT Links
No full textThis paper analyzes the problem of maximizing the gains of a single transmitter-single receiver inductive resonant Wireless Power Transfer link (WPT). Two different approaches are considered and compared: the use of impedance matching networks and the use of additional resonators (relay elements). It is shown that, if from a theoretical point of view the two approaches are equivalent, in some practical cases the maximization of the gains by means of relays may not be feasible
Multitone intermodulation and RF stability analysis of MEMS switching circuits by a globally convergent harmonic balance technique
No full textThe paper introduces an extended harmonic-balance CHB)technique allowing the efficient computation of distortion effects due to MEMS nonlinearities in RF circuits containing microelectromechanical components. The ordinary HB equations are complemented by an auxiliary set of equations describing the nonlinear dynamics of the moving bridges, and the two sets are solved simultaneously by an inexact Newton iteration. Convergence problems are solved by advanced numerical techniques including special state variables and globalisation by a trust-region technique coupled to the GMRES iteration with restarting. The responses of a basic MEMS switching structure to multitone excitations and to digitally modulated RF signals are examined in detail.RF stability is investigated by a numerical implementation of bifurcation theory
Power-Handling Capabilities Optimization of MEMS-Reconfigurable Antennas
No full textThe paper discusses a rigorous simulation of reconfigurable integrated antennas operated by MEMS switches, based on a combined nonlinear/electromagnetic (EM)/structural approach. The patch antenna is characterized as a linear multiport network by EM analysis. The MEMS are described as nonlinear components by means of their structural-based electromechanical equations. The accuracy of the nonlinear model is validated by comparison with measures. A rigorous analysis of the entire nonlinear (sub)system behavior is then performed by the harmonic balance (HB) technique combined with a numerical implementation of bifurcation theory. This allows an in-depth investigation of the complex stability pattern of the reconfigurable patch antenna including power-handling capabilities depending on MEMS switches position
A MEMS-Based Wide-Band Multi-State Power Attenuator for Radio Frequency and Microwave Applications
No full textIn this work we present a novel implementation of a multi-state RF (Radio Frequency) power attenuator, entirely realized in MEMS (MicroElectroMechanical-Systems) technology. The network, based on a CPW (Coplanar Waveguide) structure and fabricated in FBK technology, features several resistors realized with an highly-doped poly-silicon layer. Each resistor can load the RF line or can be shorted, depending on the state (actuated/not actuated) of electrostatically controlled suspended membrane-based MEMS switches. The network realizes 128 attenuation levels with flat characteristics over broad frequency ranges. The network features two sections, namely a series and a parallel one, that are experimentally characterized in a few of the possible configurations up to 30 GHz and simulated within CSTTM Microwave Studio. After validating the simulated results for the two sections, simulated results of the whole RF-MEMS-based power attenuator are presented and discussed
Circuit-level nonlinear/EM co-simulation and co-design of UWB receivers
No full textThe paper describes an efficient and accurate circuit-level approach to the co-design of UWB receivers integrated with broadband antennas. A full nonlinear simulation of the front end is integrated with the electromagnetically (EM)-based description of the antenna impedance and far-field performance. For each direction of incidence of the transmitted UWB pulse, a circuit description of the receiver excitation under the form of a set of Norton equivalent current sources is generated by EM theory. The source internal impedance is the antenna impedance deter-mined by full-wave EM analysis. The receiver nonlinear analysis is carried out by a model-order reduction Harmonic Balance (HB) technique based on Krylov subspaces. The procedure allows the actual receiver sensitivity to be accurately evaluated by tak-ing into account the amplitude and phase distortion introduced by the antenna, which may significantly change with the UWB pulse direction of incidence. It also allows an effective prediction of the link power budget, which is particularly critical in ultra-low power Impulse Radio (IR) -UWB applications
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