Source Reconstruction in Near-Field Scanning Using Inverse MoM for RFI Application

The ability to predict the electric and magnetic fields generated by a component can solve many in-system interference problems before they occur. In this article, methods are presented to predict the high-frequency near electric and magnetic fields from a component using a method of moment approach. The current representation is estimated from a near electric-field scan by solving the electric field integral equation. The reconstruction method was validated with measurements of a test board containing a buffer integrated circuit. The current representation was shown to accurately predict fields at locations both above and to the side of the buffer with less than a 3.5-dB average error. Here, a near-field scan was only performed on a flat plane above the emitter and was used to predict sources to the side of the emitter. To accurately predict fields to the side of the emitter, the current representation must be defined on a surface between the emitter and the prediction location. An error analysis was performed to understand the impact of scan plane parameters, such as the size of the scan plane, the size of the current representation, and the relative distance between the current representation and the estimated fields on prediction accuracy.

I. Introduction

Due TO the complexity and reduced size of new wireless products, it is important to predict the potential for radio frequency interference (RFI) between components, such as from integrated circuits (ICs) and high-speed traces to nearby antennas. Unwanted coupling from high-frequency components may degrade the radio frequency (RF) performance of the wireless receivers. Potential problems can be mitigated by predicting the near electric and magnetic fields generated by components early in the design process and then modifying the design to minimize coupling issues.