Conference Agenda

The efficient computation of higher-order modes in multiconductor transmission lines is crucial, as these modes alter the distribution of TEM modes and increase cross-talk, affecting electromagnetic compatibility and signal integrity in high-frequency circuits. Traditional numerical methods face challenges in handling large-scale eigenvalue problems due to increasing computational complexity. Quantum computing offers a promising alternative by leveraging quantum principles such as superposition and entanglement to solve large eigenvalue problems more efficiently than classical solvers. In this work, we explore the variational quantum eigensolver as a quantum-assisted method for waveguide modal analysis. Starting from the Helmholtz equation for TM modes, we discretize the system using the finite difference method, map the Hamiltonian onto the Pauli basis, and implement the VQE with a hardware-efficient ansatz optimized via BFGS on the Qiskit statevector simulator of IBM. As a test case, we analyze a shielded stripline. The quantum eigensolver successfully computes the first two TM modes and their cutoff frequencies while reconstructing the Ez and Ex field distributions at 1 GHz. This preliminary study shows the feasibility of quantum algorithms for solving large eigenvalue problems in computational electromagnetics where classical computing can fail, opening new possibilities for the efficient analysis of shielded multiconductor transmission lines, where higher-order modes significantly impact cross-talk and signal integrity. Future work will focus on scaling this approach to analyze multiconductor propagation in complex transmission-line structures.

This paper investigates the performance of three hierarchical matrix (H-matrix) formats for modeling electromagnetic devices using the Electric Field Integral Equation (EFIE) and the Augmented EFIE (A-EFIE) formulation. These methods are applied to a benchmark problem, the single-ended microstrip transmission line, to evaluate their efficiency in terms of memory usage and accuracy.

A passive and inherent stable modal equivalent circuit for microstrip structures is presented. The layered media of the microstrip structure is modelled using dyadic Green's functions derived by the discrete complex imaging method (DCIM). Based on the partial element equivalent circuit (PEEC) equation system an eigenvalue problem is set up to obtain the eigenvalues and eigenvectors of this system. From which a fast converging, passive and inherent stable equivalent circuit is derived. Such an equivalent circuit can be easily connected with other network elements (active/passive and linear/non-linear) or via models, allowing a seamless integrated system analysis. Simulations in the frequency and time domain confirm the validity of the proposed method very well.

A new method for converting a discrete field description of a system by the finite element method (FEM) into an equivalent-circuit representation based on modal analysis is presented. This new approach allows to include dispersive materials with frequency-dependent dielectric losses over the whole considered bandwidth. To account for the frequency-dependent permittivity which is described by a Debye model, the previous modal network representation of the system is extended by additional modal coupling elements. The passivity of the additional modal coupling elements ensures the inherent stability of the system. The proposed method is validated by a complex example structure in the frequency and time domain.

This paper describes the formulation of an alternative accelerated approach for the characteristic mode analysis (CMA). The approach provides the same results as the conventional CMA for the modes that are resonant in the considered bandwidth. However, the necessary computational effort is significantly reduced due to the considerably smaller system size, which enables a CMA analysis over a wide frequency range. This allows a targeted broadband EMC analysis, which is demonstrated by examining the immunity behavior of an example system.