The UK amateur radio licence was updated on the 18th of May 2021 to include new clauses about exposing members of the public to EMF (Electromagnetic fields). Exams after 31st August 2022 will include questions on this topic
What does the licence say?
The EMF section applies to any transmissions at powers over 6.1 watts ERP (or 10 Watts EIRP), and is designed to ensure that licence holders comply with the ICNIRP limits about exposure of radio signal field strength to members of the public.
All radio amateurs 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 limits specified by a body called the ICNIRP.
How do I comply with the new rules?
Most amateurs will simply complete an assessment to see if their setup complies. 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.
The following short video provides an overview of how to complete an assessment:
Online Assessment Links
The RSGB has released an amateur-friendly version of Ofcom’s EMF calculator:
You’ll need to type in several bits of information, to calculate the safe distance in meters. The important data is:
- Transmit power
- Frequency
- Mode (SSB, FM, etc) – Taking SSB as an example, when we talk quietly, we radiate less power than when we shout
- Transmit time – We can specify our measurements based on a 6-minute period. As we will spend some of that six-minute period listening, we can specify what percentage of a sample 6-minute period we spend transmitting
- Antenna gain – This of course affects the ERP
- Co-ax loss – Some power is lost in the feeder, reducing the amount of power we radiate from the antenna
- Antenna height off the ground – Obviously affects how likely members of the public are to be in the ‘unsafe zone’
More information:
- Guidance from Ofcom: Ofcom EMF Guidance
- Guidance from RSGB: RSGB EMF Guidance
- Essex Ham Guide: Essex Ham Getting Started: EMF (PDF guide)
- Essex Ham Views: Essex Ham: EMF Licence Changes
