Worth knowing: Bad PCB Design Leads To Unwanted Radiation скачать в хорошем качестве

Worth knowing: Bad PCB Design Leads To Unwanted Radiation

PCB traces can quickly turn into unintended antennas. All it takes is poor layout. Specifically: gaps in the ground plane. In this example, we're looking at a simple PCB with two identical traces. Both are properly terminated with 50-ohm loads, and both are driven by the same signal source, a comb generator that produces a wide range of harmonics. But there's a critical difference: the bottom layer of the board is a solid ground pour, except under one of the traces, where a deliberate ground cutout has been placed. When we scan the area above the traces using a magnetic near-field probe, the results are striking: the trace above the ground cutout radiates significantly more than the one over solid ground. Unlike DC signals that follow the path of least resistance, high-frequency signals rely on the lowest-impedance return path, which runs directly beneath the signal trace. If this path is interrupted, the return currents are forced to detour, causing a substantial increase in radiated emissions. 👉The takeaway is simple: high-frequency signal traces must always run over a continuous, unbroken ground plane! #electricalengineering #electronics #hamradio #physics