Finite difference time-domain analysis of planar microwave circuits

Contents The application of finite difference time domain analysis techniques to planar microwave integrated circuit design is discussed. It is shown that using this technique, three-dimensional discontinuity problems in planar microstrip and coplanar circuits can be analyzed in a full-wave approach.

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Finite-Differenzen-Analyse von planaren Mikrowellen-schaltungen im Zeitbereich

Übersicht Es wird die Anwendung der Finiten-Differenzen-Analyse elektromagnetischer Felder im Zeitbereich auf den Entwurf integrierter Mikrowellenschaltungen diskutiert. Es wird gezeigt, daß durch Anwendung dieser Technik eine Lösung der Beschreibungsprobleme für dreidimensionale Schaltkreis-Diskontinuitäten in planarer Mikrostreifenleitungstechnik und in koplanarer Leitungstechnik unter Berücksichtigung der vollen Welleneigenschaften gefunden werden kann. Verschiedene Beispiele von Analysen planarer Mikrowellenbauelemente werden diskutiert und die Ergebnisse mit Messungen verglichen.

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Dedicated to Prof. Dr.-Ing. Herbert Döring on the occasion of his 80th birthday     

Einflüsse von Triazolapplikationen auf Kornertrag und -qualität von Winterraps

Effects of Growth Substance Applications (Triazole) on Yield Formation and Grain Quality of Winter Rape Field trials have been conducted for two years (1986/87 and 1987/88) with cv. Lirabon (low erucic acid and low glucosinolate content). At several growth stages uptil beginning of flowering and at different rates the triazole RSW 0411 (Bayer) was applied. The problem was to investigate growth regulator effects on agronomically important traits, the utilization of yield potential and on seed quality. Applications during stem elongation reduced plant height phoma lingam infestation and lodging. Branching and numbers of pods/plant increased, partly on costs of pod filling. In 1986/87 grain yields/ha indicated (not significant) increases without any effects on grain quality. In 1987/88 grain yield/ha decreased significantly combined with increasing protein- and glucosinolate contents.     

Equivalent circuits for transient and steady state calculations in coaxial tubes

Contents Transient field and current have been calculated in coaxial tubes for a given applied voltage wave form. The boundary value problem of the diffusion equation has been solved. The solution lead to equivalent circuits i.e. circuits with lumpedL, R elements which can describe the impedance behaviour as accurately as required. This method could well be applied to find short circuit currents and steady state losses in cables, bus bars and gas insulated transmissions.

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Ersatzschaltbilder zur Berechnung von transienten und stationären Zuständen in koaxialen rohrförmigen Leitern

Übersicht Transiente Felder und Ströme werden in koaxialen Zylinderanordnungen bei eingeprägter Spannung berechnet. Das entsprechende Randwertproblem aus der Maxwellschen Theorie wird gelöst. Die Lösung führt zu einem equivalenten Ersatzschaltbild mit konzetrierten Elementen. So kann das Impedanzverhalten beliebig genau beschrieben werden. Diese Methode kann für die Berechnung von Kurzschlußströmen und stationären Verlusten in Kabeln, Sammelschienen und gasisolierten Übertragungstrecken von Bedeutung sein.

     

MIMO systems with full and reduced hardware complexity

MIMO (multiple-input-multiple-output) systems propose enormous gains in the capacity of wireless systems without requiring more spectral resources. This paper first gives an overview of the use of MIMO for diversity and spatial multiplexing, and the use of channel state information in MIMO systems. It then explores the use of antenna selection as a means for the reduction of the hardware complexity. It is shown that the performance in a spatial-multiplexing application is almost as good as that of full-complexity systems as long as the number of RF chains is at least as large as the number of data streams.     

Elastodynamic parameters for dynamic interface fracture mechanics

Summary Dynamic extension of cracks running along curvilinear interfaces of brittle bimaterials subjected to mechanical crack surface loads and superimposed thermal strains acting along the ligament is considered. This paper especially addresses the provision and discussion of elastodynamic interface parameters in order to assess quantitatively the bimaterial fracture in view of the governing physical features: applied mechanical and thermal strain loading, existence of an interface, crack-tip velocity and curvature of the interface contour. By utilizing the linear theory of thermoelasticity and adopting Stroh's method of generalized complex potentials, from the corresponding boundary and continuity conditions vectorial Hilbert problems are derived. It is shown that the parameters of the eigenvalues and of the eigenvectors of the Hilbert problems can be interpreted as elastodynamic interface mechanics parameters reading (,v _p, _Hf , _Hf ). Generalized Dundurs parameters of dynamics (, ) and consequently an associated generalized Dundurs diagram of dynamics are proposed. While the aforementioned elastodynamic interface parameters (, ,v _p, _Hf , _Hf ) do not assume the interface to be damaged, interfaces with running interface cracks generally cause two additional interface parameters, denoted as bimaterial constants (, _Hf ), where the latter is specific to the curvature of the interface in conjunction with the velocity of the interface crack. However, the bimaterial constants (, _Hf ) can be traced back to interface parameters for an uncracked bimaterial, namely to (, _Hf ).     

Solving non-linear elliptic difference equations by extendable sparse factorization procedures

New extendable LU sparse factorization procedures are presented for the solution of non-linear elliptic difference equations. The derived iterative methods are shown to be both competitive and computationally efficient in comparison with existing schemes. Application of the methods on non-linear elliptic boundary value problems both in two and three space dimensions are discussed and numerical results are given.     

Some basic results on M-matrices in connection with the Accelerated Overrelaxation (AOR) method

This paper extends some recent results by Varga concerning the theory of M-matrices, in connection with the well known iterative methods of Jacobi, of Extrapolated Jacobi and of Successive Over-relaxation, in two directions: i) The iteration matrix of the iterative scheme considered is more general than that of the aforementioned methods and may include a diagonal part and ii) the theory is presented in such a way that the number of equivalent statements given in the text covers the Accelerated Overrelaxation (AOR) method introduced by the present author not long ago.     

Numerische Lösung gewöhnlicher Differentialgleichungen mit Splinefunktionen

In this paper a general procedure to obtain spline approximations for the solutions of initial value problems for ordinary differential equations is presented. Several well-known spline approximation methods are included as special cases. It is common practice to partition the interval for which the initial value problem is defined into equidistant subintervals and to construct successively the spline approximation; thereby the spline function has to satisfy certain conditions at the knots. In the general procedure presented here additional knots are admitted in every subinterval. At these points which need not be equally spaced the spline approximation has to fulfill analogous conditions as at the original knots. Convergence and divergence theorems are proved; especially the influence of the additional knots on convergence and divergence of the method is investigated.