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Purpose -- The purpose of this paper is to present an optimization process for the design of a 2×2 patch antenna phased array with application for an UHF RFID system. Design/methodology/approach -- The optimization process is based on a method of moment (MoM)-solver, which was individually made to create such patch antenna phased arrays and simulate the radiated field pattern. In combination with this MoM-solver, a GUI, which gives the opportunity to change every physical antenna factor and create the antenna structure within a few minutes is presented. Furthermore the golden section search method is used to produce an even better solution in a more efficient way compared to the first attempt. After the simulation, different types of presentation of results can be chosen for a fast and easy optimization. Findings -- The design process is discussed while the authors try to optimize the distance between the elements and the difference of input phase for each patch element. The final goal is to create an antenna with maximum directivity and coverage of field pattern. Practical implications -- A physical implementation of an optimized patch antenna phased array and the results of measurement are presented in the end. Originality/value -- An optimization process for the design of a 2×2 patch antenna phased array with application for an UHF RFID system is presented. Furthermore the golden section search method is combined with the design process to increase the accuracy of the solution and decrease the time effort. [ABSTRACT FROM AUTHOR]

Purpose – This paper seeks to give an outline about the geometric concept of electronic circuits, where the jump behavior of nonlinear circuits is emphasized. Design/methodology/approach – A sketch of circuit theory in a differential geometric setting is given. Findings – It is shown that the structure of circuit theory can be given in a much better way than by means of a description of circuits using concrete coordinates. Furthermore, the formulation of a concrete jump condition is given. Originality/value – In this paper, an outline is given about the state of the art of nonlinear circuits from a differential geometric point of view. Moreover, differential geometric methods were applied to two example circuits (flip flop and multivibrator) and numerical results were achieved. [ABSTRACT FROM AUTHOR]

Purpose – This paper aims to present a method for the efficient reduction of networks modelling parasitic couplings in very-large-scale integration (VLSI) circuits. Design/methodology/approach – The parasitic effects are modelled by large RLC networks and current sources for the digital switching currents. Based on the determined behaviour of the digital modules, an efficient description of these networks is proposed, which allows for a more efficient model reduction than standard methods. Findings – The proposed method enables a fast and efficient simulation of the parasitic effects. Additionally, an extension of the reduction method to elements, which incorporate some supply voltage dependence to model the internal currents more precisely than independent current sources is presented. Practical implications – The presented method can be applied to large electrical networks, used in the modelling of parasitic effects, for reducing their size. A reduced model is created which can be used in investigations with circuit simulators requiring a lowered computational effort. Originality/value – Contrary to existing methods, the presented method includes the knowledge of the behaviour of the sources in the model to enhance the model reduction process. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to investigate the accuracy of different force calculation methods and their impact on mechanical deformations. For this purpose, a micrometer scaled actuator is considered, which consists of a micro-coil and of a permanent magnet (PM) embedded in a deformable elastomeric layer. Design/methodology/approach – For the magnetic field evaluation a hybrid numerical approach (finite element method/boundary element method (FEM/BEM) coupling and a FEM/BEM/Biot-Savart approach) is used, whereas FEM is implemented for the mechanical deformation analysis. Furthermore, for the magneto-mechanical coupling several force calculation methods, namely the Maxwell stress tensor, the virtual work approach and the equivalent magnetic sources methods, are considered and compared to each other and to laboratory measurements. Findings – The numerically evaluated magnetic forces and the measured ones are in good accordance with each other with respect to the normal force acting on the PM. Nevertheless, depending on the used method the tangential force components differ from each other, which leads to slightly different mechanical deformations. Research limitations/implications – Since the force calculations are compared to measurement data, it is possible to give a suggestion about their applicability. The mechanical behavior of the actuator due to the acting forces is solely calculated and therefore only an assumption concerning the deformation can be given. Originality/value – A new kind of micrometer scaled actuator is numerically investigated by using two different hybrid approaches for the magnetic field evaluation. Based on those, the results of several force calculation methods are compared to measurement data. Furthermore, a subsequent structural analysis is performed, which shows slightly different mechanical deformations depending on the used force calculation method. [ABSTRACT FROM AUTHOR]

The conventional treatment of thermal noise is based on Nyquist's theorem. This theorem has only been derived for linear, reciprocal (we define "reciprocal networks" as networks that are built of reciprocal network elements) networks. In this paper a description of thermal noise in reciprocal non-linear RLC networks is presented. This description is derived from first principles, i.e. from a direct application of non-equilibrium thermodynamics (irreversible thermodynamics) to electrical networks. As an example, the class of "complete" non-linear networks is considered. Using the idea of equivalent n-ports, the theory's extension to certain classes of transistor circuits should be possible. [ABSTRACT FROM AUTHOR]