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An efficient adjoint variable method technique is developed for time-domain sensitivity analysis of planar structures with transmission-line modeling complemented by a first-order one-way wave-equation absorbing boundaries. A backward-running adjoint simulation is derived and solved. The validity of the technique is illustrated through three microstrip circuits. The examples demonstrate the efficiency and accuracy of the technique in comparison with the classical finite-difference approaches to the estimation of the response sensitivities. Copyright © 2007 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We present an efficient self-adjoint approach for the computation of response derivatives in lossy inhomogeneous structures with time-domain electromagnetic solvers. Our approach yields the responses and their derivatives with only one system analysis regardless of the number of optimizable parameters. The only requirement is to access the field solution at the perturbation grid points. The computation is performed as an independent post-process outside the solver. This makes our approach easy to implement as stand-alone software, which aids microwave design based on commercial computer-aided design packages. We show that our sensitivity analysis approach yields Jacobians of second-order accuracy for lossy dielectric structures. The approach is verified through 1-D, 2-D and 3-D examples using the time-domain field solutions obtained with solvers based on the finite-difference time-domain (FDTD) and transmission line modeling (TLM) methods. Copyright © 2007 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We present a novel efficient algorithm for the estimation of S-parameter sensitivities in homogeneous and lossless transmission line modelling (TLM) problems. Our approach estimates S-parameter adjoint-based sensitivities without actually carrying out any adjoint simulation. By applying a transformation to the original TLM simulation we establish an isomorphism between the original and the adjoint problem. The unique properties of the TLM node in a lossless and homogeneous problem are also exploited in establishing the isomorphism. For an electromagnetic structure with Np ports, only the Np original simulations utilized in evaluating the S-parameters are required to estimate their sensitivities as well. Our novel approach is illustrated through estimating S-parameter sensitivities with respect to waveguide discontinuities. Good match is obtained between our sensitivity estimates and those calculated using finite differences at the response level. Copyright © 2005 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A new approach to transient electromagnetic (EM) analysis in terms of wave potentials is presented. It is based on the EM field and source scalarization in a non-uniform medium. The algorithm computes two scalar wave functions of space-time, which constitute a complete 3-D solution. They represent the time-dependent values of two collinear (electric and magnetic) vector potentials of known fixed direction throughout the computational volume. Auxiliary source functions are also computed but only at the location of material non-uniformities. A finite-difference implementation in the case of metallic boundaries and inclusions is considered. The algorithm offers approximately 30% reduction of the computation time and memory requirements in comparison with the FDTD method based on the Maxwell curl equations. The technique is illustrated with a number of waveguide examples. Copyright © 2004 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]