Investigating Low-Frequency Electromagnetic Fluctuations on PCB Surfaces: A Near-Field Analysis of CBCPW Transmission Lines up to 15.2 MHz

Abstract

The paper employs statistical methods to model low-frequency electromagnetic field fluctuations over printed circuit boards (PCBs) using near-field measurements within the frequency domain along the Coplanar Broadband Capacitance Wave (CBCPW) transmission line. The study characterizes electromagnetic noise profiles up to 15.2 MHz, assesses the impact of transmission lines (TL) on PCB environments, and explores the effects of signal interference. Advanced statistical methods, including the Hurst exponent and Ljung-Box tests, are integrated with traditional near-field measurements to quantify electromagnetic noise persistence and independence across frequencies. Additionally, 2-D autocovariance analysis provides a precise evaluation of electromagnetic field characteristics over the PCB surface. This research further develops a model for electromagnetic field fluctuations by incorporating theoretical frameworks aligned with stochastic Maxwell’s equations and addressing challenges such as measurement uncertainty and mechanical stepping of the probe head over the PCB surface. The autocovariance function enhances data analysis robustness, which is advantageous for the sparse data typically associated with PCBs and integrated circuits. Measurements extend up to 328.27 MHz, with a focus on significant fluctuations up to 15.2MHz due to their dominance over the measured noise. This study proposes a comprehensive statistical and modelling approach tailored for applications involving CBCPW transmission lines, especially relevant to microscale detectors and sensitive electronic devices.

Keywords

• Magnetic field measurement
• stochastic processes
• white noise
• near-field
• PCB
• CBCPW