Low-frequency to high-frequency stabilized inverse source solutions with validation measurements

• Applicants: Professor Dr.-Ing. Simon Adrian; Professor Dr.-Ing. Thomas Eibert
• Subject Area: Communication Technology and Networks, High-Frequency Technology and Photonic Systems, Signal Processing and Machine Learning for Information Technology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 504345461

High-frequency, electromagnetic near-field measurements and corresponding solutions of inverse source problems have become an established technology in the field of antenna measurements during the past years. However, when the frequencies become smaller (e.g., as needed and encountered in the diagnostics of electronic devices, in dosimetry, or corresponding imaging approaches), or if the resolution shall be raised by increasing the number of unknowns and measurement samples, the existing inverse source algorithms become unstable due to several types of breakdown. In this project, it is proposed to investigate and establish a collection of stabilization procedures for the involved radiation integral representations and transfer the gained insights to the related measurement and acquisition schemes. Novel and stable integral equation formulations will be derived with a particular focus on low- and mid-frequency measurement scenarios. Moreover, wideband stable fast integral solvers for the inverse source problem will be established together with preconditioners, which will allow achieving very high-resolution inverse source results of problems with several millions of unknowns. Validation measurements with high-precision measurement setups for measuring electric and magnetic fields by dedicated measurement probes will be performed and investigated in parallel to the theoretical investigations, where in particular combined measurements of electric and magnetic fields according to the underlying field topology will be considered in order to support stabilized inverse source solutions. Test targets producing a variety of field effects and with a variety of geometrical details of varying resolution will be measured and characterized.

• DFG Programme: Research Grants