Past Columns

A VSWR bridge and a magnetic near field probe (NFP) are very valuable tools to find resonances in RF and EMI/EMC applications as tuning, shielding, etc.

Usually HF filters are designed using inductors with cores. In this way a medium/high inductance value is obtained in small size components. But using cores has a limitation.

The mirror technique is a very old technique to be used with PCBs when failing in radiated EMC tests. An easy solution to avoid changes in layout if the technique can be applied to your product.

Clock signals from 1 to 100MHz are usually responsible for radiated EMC problems in HF/VHF range. Harmonics are the culprits, but think in current, not in voltage.

Inductive loads and interrupted currents are an explosive combination. High voltages, arcing, and HF broadband noise are some typical effects. The phenomena behind these transients is complex, but it is not difficult to understand the fundamentals and how to minimize the effects.

Snubbers are RC networks that are really useful for protecting components (transistors, diodes, etc.) and reducing EMI, especially in switching applications.

Can the hi-pot test and the insulation resistance test be combined into a single measurement? Let’s discuss each of these parameters as circuit parameters and as safety parameters.

RF signals entering in a system and being rectified can interfere seriously. That has been classically the case of audio noise in speakers because of mobile phones using TDMA technology. The problem is now very common in products with wireless RF funcionality in products with audio areas.

For production-line testing, the 25- or 30-amp grounding continuity test is not likely to identify construction anomalies that would not also be identified by a simple low-current test.

High-current grounding impedance tests have been specified in safety standards for many years. There are two, independent sources for these tests.