Completing an EMF Assessment

Since May 2021, radio hams in the UK have been required to comply with new sections of our licence about exposing members of the public to electromagnetic fields (EMF).

What are the rules?

The rules apply to transmissions at powers over 6.1 watts ERP (stated as 10 Watts EIRP). Over this limit, checks need to be made to make sure that signals comply with international limits set by a body called ICNIRP.

All radio hams who transmit more than 6.1 watts e.r.p will need to carry out an assessment to make sure that members of the general public are not exposed to field strengths greater than the published limits.

How do I complete an assessment?

Free tools are available from the RSGB. Amateurs need to complete the assessment so that if they are asked by Ofcom, they can present the calculations and demonstrate no risk to the general public.

To perform an assessment, you’ll need to have the following information to hand:

  • Band – The band you’re planning to transmit on
  • Mode – FM voice, SSB, AM, data mode, digital voice, etc
  • Transmit power Power
  • Transmit percentage over 6 minutes – typically if you talk for 3 minutes and listen for 3 minutes, that’s 50% 
  • Feeder type and length of feeder run (as there will be loss)
  • Antenna type
  • Antenna height

EMF Assessment Video

The following short video provides an overview of how to complete an assessment:

EMF Assessment – HamTrain Video

Online Assessment Links

The RSGB has released an amateur-friendly version of Ofcom’s EMF calculator:

More information:

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