Wolfgang Ackermann

Antenna Modeling for Inductive RFID Applications Using the Partial Element Equivalent Circuit Method

In this paper equivalent circuit models of inductive coupled radio frequency identification (RFID) antenna systems are extracted by means of the partial element equivalent circuit (PEEC) method. Each antenna impedance is analyzed separately regarding frequency dependent behavior including skin- and proximity effects as well as parasitic capacitances. On the contrary, the inductive coupling between any two coils is computed for an arbitrary 3D spatial arrangement by a filamentary mutual inductance computation technique, allowing for fast spatial sweeps. Both models are combined to a reduced equivalent circuit that maintains the topology of mutually coupled inductances. The described approach is tested with a conventional reader transponder arrangement and compared with the full PEEC models.

Generation of physical equivalent circuits using 3D simulations

Physical equivalent circuits are powerful tools for EMC analysis of electronic devices, however their generation is in general cumbersome. In this paper, a procedure to generate physical equivalent circuits using 3D simulations is described. The method is based on a numerical computation of Z parameters using 3D simulations. Equivalent circuit tpoplogy and parameters are extracted from the simulated Z parameter matrix. Maxwells equations are used in a reduced form to eliminate all effects that cannot be modelled by equivalent circuits.

Proper Combination of Integrators and Interpolators for Stable Marching-on-in-Time Schemes

Mathematicians have proven that few specific collocation methods provide stable numerical solution for the delay differential equations provided the accuracy order of the finite difference approximation matches to that of the temporal interpolation. To adjoin this important conclusion to the development of stable time-domain field integral equation-based solvers, this paper investigates the impact of diverse proposed interpolators over conveniently usable integrators.

Survey of Temporal Basis Functions for Integral Equation Methods

To make the implicit marching-on-in-time schemes stable for practical applications, choices of appropriate temporal basis functions are investigated. The quadratic and cubic cardinal B-spline functions are introduced as new time bases for which the numerical solution of the electric field integral equation demonstrates that they can compete with the time shifted Lagrange interpolating functions in terms of accuracy and stability. It is shown that especially for small time step sizes using the analytical closed-form derivatives of the bases tremendously enhance the extension of the stable region in comparison with the results obtained using available consistent integrator-interpolator pairs.

Linearization of Parametric FIT-Discretized Systems for Model Order Reduction

Electrodynamic field simulations typically require the solution of large linear systems which may depend on several variables. Model Order Reduction Techniques offer an approach to solve these multivariate problems in a reasonable time. This paper presents an Order Reduction Method and the required system equation linearization for structures discretized by the Finite Integration Technique (FIT) depending on frequency and length variation.

Data Base Extension for the Ensemble Model Using a Flexible Implementation

To guarantee an adequate design and a proper functionality of various machine components it is of primary importance to perform detailed studies of the charged particle transport. However, it is often not necessary to initiate individual kinetic simulations based on the discrete particle movements. When the time evolution of such integral quantities like average or rms dimensions, total energy or projected emittances is of the research interest, it is worth treating an investigated particle ensemble as a whole and applying a macroscopic formulation. Based on the moment method a fast C++ code capable to handle various beam line elements has been implemented. The present paper treats the implementation issues of the code and discusses the simulation results for such axial magnetic multipoles like quadrupoles and sextupoles under the influence of fringe field effects.

Eigenmodes of electrical components and their relation to equivalent electrical circuits

Physical equivalent electrical circuits facilitate root-cause analysis of resonance phenomena in electromagnetic components. We extend an existing formalism for the generation of physical equivalent circuits by linking the resonant behaviour of the equivalent circuit with 3D electromagnetic eigenmodes of the component. We define a figure of merit, which we call quality, describing the frequency range of validity and the accuracy of equivalent circuit descriptions of 3D components. We validate our approach by analyzing practical examples.

Adaptive Time Stepping for Electromagnetic Models With Sinusoidal Dynamics

The numerical integration of electromagnetic models with sinusoidal excitation should be implemented in a special manner because standard adaptive Runge-Kutta integration methods do not work properly if the difference between the main and the embedded order of approximations is one. In this paper, a new class of adaptive time stepping schemes specially designed for the numerical integration of the electromagnetic models with sinusoidal dynamics is proposed.

Adaptive time integration for electromagnetic models with sinusoidal excitation

Purpose – To provide a reliable numerical technique for the time integration of the electromagnetic models with sinusoidal excitation.Design/methodology/approach – The numerical integration of an electrotechnical problem is commonly carried out using adaptive time stepping. For one particular selected time step, Runge‐Kutta (RK) adaptive integration methods deliver two approximations to the solution with different order of approximation. The difference between both is used to estimate the local error.Findings – Standard error‐controlled RK time integration fails for electromagnetic problems with sinusoidal excitation when the adaptive time step selection relies upon the comparison of a main solution and an embedded solution where the difference of orders is one. This problem is overcome when the embedded solution differs by two orders of approximations. Such embedded solution is efficiently constructed by putting appropriate order conditions on the coefficients of the Butcher table.Originality/value – Usi...

Wien filter as a spin rotator at low energy

The Wien filter is well known as a common energy analyzer and is also used more and more as a compact variant of a spin rotator at low energy for electrons. The Wien filter is based on homogenous magnetic and electric fields which are perpendicular to each other and transverse to the direction of the electrons. The rotation of the spin vector is caused by the magnetic field. If the force equilibrium condition is fulfilled the beam should not be deflected at the Wien filter. Simulations show that in the fringe fields the electrons get a kick. Therefore full 3D simulations of the electromagnetic fields and beam dynamics simulations are studied in detail at the example of the Wien filter at the new polarized 100 keV electron injector at the S-DALINAC. The results of the simulations with CST Design Environmenttradeand V-Code are presented.