A New Method for Identifying Coupling Paths and Mitigating Crosstalk in PCB Design

Crosstalk in printed circuit boards (PCBs) poses challenges for signal integrity in high-frequency and compact systems, yet mitigation is often guided by empirical rules rather than systematic analysis. It is of particular concern in applications such as high-speed digital systems, multi-antenna wireless systems, and automotive radar, where unwanted coupling can lead to bit errors, degraded channel isolation, or false detections with direct impact on end-user performance and safety. To systematically study crosstalk in PCB transmission lines, this thesis adapts a reaction-theorem-based method originally developed for antenna placement optimization. Within this framework, two formulations are employed to evaluate coupling: the coupling density, denoted related to and the generalized impedance density, denoted , related to , which is proportional to under weak coupling.

Simulations of microstrip and stripline geometries in CST show that both and visualizations identify the regions responsible for coupling. For countermeasure design, is particularly useful, since results demonstrate that placing shorting vias or continuous copper walls in regions of positive reduces crosstalk, whereas placement in negative zones increases it. In striplines, an iterative application of this method can suppress coupling almost completely in a narrowband case, achieving more than 50 dB reduction in . The method can be easily integrated into existing electromagnetic design workflows and was found to add only a small computational cost compared to the full-wave field simulations already required for such systems.

The results establish reaction-theorem-based visualization as a systematic tool for identifying coupling paths and guiding countermeasure design in PCBs.
Beyond the methodological contribution, the approach offers potential for more sustainable electronics design through reduced design iterations and material use, while at the same time supporting improved signal integrity, better reliability in high-frequency operation, and more efficient use of compact layouts.