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Interference Technology

For EMI / EMC Engineers

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Amplifiers

An Isotropic Probe for Radiated Susceptibility Measurements from 10kHz to 18GHz and 5V/m to 220V/m

 

Abstract: Isotropic probes are available for radiated susceptibility test level measurements from 100kHz to 6GHz, 2MHz to 18GHz, 2MHz to 40GHz and 2MHz to 60GHz. For MIL-STD-461 and DO-160 testing a frequency range of 10kHz to 18GHz would be better and a possible solution is presented here.   Introduction The probe described in this paper has three separate sections, … [Read more...]

EMC Confidence Checking

 

I was recently working with a manufacturer of stand-alone ticket machines, who had big problems with Ethernet-related emissions. Long story short – it was the Ethernet hub they had incorporated in their machine. They had assumed that all CE-marked Ethernet hubs would be equally good for EMC, and they had several different types lying around their design department. We tested … [Read more...]

Mains Harmonic Current Emissions are Always Bad – It is Risky to Rely on the Limits or Exclusions in the Standards

 

Many (perhaps all) of EMC standards that are listed under the EMC Directive, that set limits for mains harmonic emissions, have exclusions (‘let-outs’) for certain types of equipment, especially: (these examples are from IEC/EN 61000-3-2 Ed.5:2018) Lighting equipment with a rated power of less than but not equal to 5W Equipment with a rated power of 75W or less, e.g. … [Read more...]

Key Points to Remember While Choosing PCB Assembly Company

 

Once you have designed a PCB and have completed everything that needs to be done before the assembly process, you would require a PCB assembly company to assemble your PCB without any problems. After all, you've been working considerably hard to assemble the layout and the design of the PCB. You would want to be convinced that your PCB gets well-assembled. To ensure that the … [Read more...]

Review: EMI Devices Harmonic Comb Generator

 

Harmonic comb generators are handy tools for validating open area test sites or semi-anechoic chambers and I've written extensively on how to use these for various other applications (see References). Harmonic comb generators produce a range of narrow band harmonics that are typically very stable in amplitude and frequency. One of the major uses is to position one in place … [Read more...]

Risks Associated with EMC and EMI – Don’t get Confused!

 

There are many kinds of risk For example: the risk of being late for an appointment; the risk of buying a lottery ticket but  not winning a prize; the risk of designing and manufacturing a new product that might not sell well enough, etc. The above are examples of non-safety-related risks, but safety-related risks also exist. EMC1 Risk Management (or, the Risk Management … [Read more...]

A Simple Method for Estimating Radiated Emissions – Part 2

 

I recently published this blog, detailing a simple proven method for estimating the radiated E field with  specified test setup. As a result, I received the following feedback... 'This model is wrong for equipment tested over a ground plane as described. The complex correct transmission line model (less the ground plane) is given by Balanis, and a simpler but accurate … [Read more...]

A Simple Method for Estimating Radiated Emissions

 

A simple method for estimating radiated emissions I recently received the following question: How to calculate the radiated E field with following test conditions with an antenna placed 1 meter away from the test setup?: A commercial equipment under test with metal housing  Equipment placed on the grounded metallic table/plane  LISN installed (and also placed … [Read more...]

Comparison of PWM VFDs versus Resonant Link Converters – Part 1

 

AC variable frequency drives (VFDs) have been in existence in a number of forms since the early 1970s. In the early 1980s the “pulse width modulated” (PMW) VFD versions began to appear. This form of motor control produced less motor rotor and stator harmonic heating and delivered smoother torque control at slow motor speeds. Thirty years on PWM VFDs are still the most … [Read more...]

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