A simple method for estimating radiated emissions

A simple method for estimating radiated emissions image #1

17 May 2021

Author: Keith Armstrong

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?:

  1. A commercial equipment under test with metal housing
  2.  Equipment placed on the grounded metallic table/plane
  3.  LISN installed (and also placed on mentioned metallic ground plane)
  4. Cable length between LISN and equipment under test = 1.5 m (so length > lambda/4 i.e. 1.5 m > 1 meter so cable is electrically long)
  5. Cable height above ground plane = 5 cm
  6. Frequency of interest/measurement = 75 MHz 

What will be the equation to find the radiated E field with high degree of confidence?

Please open the pdf to see my reply

Photo by Emily Morter on Unsplash

Some useful references are below:-

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  • Why “CE+CE=CE” cannot be relied upon for EMC compliance
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  • How to achieve EMC Compliance under the RED
  • Practical Electronic Design Techniques for Cost-Effective SI, PI and EMC in 2021  

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