As we advised some months back in our interview with Leslie G0CIB, Ofcom has now introduced a new licence clause. Ofcom started writing to (emailing) radio amateurs at the start of March 2021 notifying them of a change to the licence conditions regarding EMF and safe exposure limits. All radio amateurs will be required to comply with the new conditions around not exposing members of the public to perceived unsafe levels of RF.
This page contains a very basic summary of what radio amateurs need to know. This is our interpretation of the situation only, and amateurs are advised to do their own reading and research.
What has changing?
The licence was updated on the 18th of May 2021 to include new wording about field strength.
The change of wording to the amateur radio licence conditions affects any transmissions at powers over 6.1 watts ERP (or 10 Watts EIRP), and is designed to ensure that licence holders will have to comply with the ICNIRP limits about exposure of radio signal field strength to members of the public.
How does that affect radio amateurs?
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.
This potentially affects your antennas at home, your in-car/mobile setup and when you operate out-and-about /P. It will also affect amateur radio clubs at club venues and on field days.
How do I comply with the new rules?
In one of the following three ways:
- Calculate your field strengths and make changes if needed – This is the route that most of us will likely go down
- Measure your emissions and make changes if needed – This involves special and expensive measuring equipment, so not ideal
- Ensure you never radiate more than 6.1 watts ERP – No-one’s preferred option
What should I do?
For many amateurs, it’s a case of using an online calculator to enter how much power you’re putting out on various amateur bands, and the calculator telling you the safe distance.
As long as members of the general public can’t stray into the “unsafe zone” and stay there for longer than the allotted length of time, then there’s no problem.
Amateurs are likely to need to retain a copy of the calculations (perhaps with a copy of their licence), so that if there’s a knock on the door from Ofcom, you can present the calculations and demonstrate no risk to the general public.
| Ofcom EMF Changes – Leslie G0CIB Interview |
How do I calculate the safe distances?
Ofcom has released a calculator (as an Excel spreadsheet). RSGB has released an amateur-friendly version:
You’ll need to type in several bits of information, to calculate the safe distance in meters. The important data is:
- Transmit power
- Frequency
By adding in amateur radio specific information to the calculator, we can reduce the calculated distance. Factors affecting amateurs include:
- 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’
What if there’s a chance of members of the public being inside the ‘unsafe zone’?
Then you potentially need to make changes – this could be: a) raising the height of the antenna, b) taping or fencing off areas, for example on a field day, c) displaying warning signs, d) reducing the power, e) repositioning the antenna to a better location.
Will this affect Foundation?
Yes. Foundation licence holders can transmit up to 10 watts. Power is measured at the feed point of antennas, and antennas have gain. ERP (Effective Radiated Power) is the power multiplied by the antenna gain, so Foundation can easily exceed 6.1 watts ERP.
If you have not already done so, you will need to carry out an assessment to check that your radio equipment operates within the ICNIRP general public limits.
Can I have an example?
Pete M0PSX has prepared an example assessment of this home setup. He has a 2m/70cm colinear white stick antenna on the roof.
To try out this new rule, I entered details of my setup into the RSGB calculator:
- Mode: FM Voice – Mode factor 100% (uses the full 50 watts when transmitting)
- Frequency: 145MHz
- Power: Radio has a maximum of 50 watts output
- Antenna gain: 3dB (according to the spreadsheet)
- TX percentage in 6 minutes: 50% transmitting (3 minutes)
- Co-ax loss (6m run of RG213 feeder) -0.5dB
- Height of antenna feed point from ground: 9m
In reality, I rarely transmit at 50 watts, and probably for less than 3 minutes every 6 minutes, so this is a “worst case”.
The RSGB spreadsheet returned a separation distance of 2.3 metres.
I entered details of 70cm – my radio can only transmit 20 watts on 70cm. Seperation distance was 1.3m.
A member of the public would have to me on my roof to be within 2.3 meters of my antenna. Therefore, no risk. Print out my calculations. Job done! I’m only required to check this again if I change my setup.
Where do I get more information?
- Guidance from Ofcom: https://www.ofcom.org.uk/manage-your-licence/emf
- Guidance from RSGB: https://rsgb.org/main/technical/emc/emf-exposure/
See Also:
Disclaimer: This is our interpretation of the situation only, and amateurs are advised to do their own reading and research, and form their own opinion on how to interpret Ofcom’s proposed changes.
Hi Peter, Your mail is very well put and interesting, there has been a lot of rumur and misinformed information said about the changes coming in, I have even heard one Radio Ham say “I`m not doing that for anyone”. Yes we know the likelihood of any law-abiding Radio ham getting a knock on the door is very remote, they don`t (as you know) have the manpower. OFCOM will I believe make an example of someone somewhere you can bet on that one, so to hammer it home that they mean business and we must comply. Then you will get the informed public that will know about the changes and how they will react, you always get one or two that will say or do something. Anyway lets hope it goes as smoothly as it can.
Many thanks for keeping up updated. Best regards Brian.
Thanks for the article! My question is what do we need to do with our assessment when complete?
What if I never transmit anymore and RX only for SSB and SWL?
Am I guilty by owning a Icom 7300 and having an antenna outside with an intermediate licence?
Just a test to see if this works
Oh well will be running under 10w soon …
As I read the ofcom document about power output, if the radio is capable of 100watts but as I do, you only use 50watts there must be a way to guarantee it cannot be turned up. If not we would have to assume worst case and calculate at 100watts. Seems to be mixed opinions. If so you can’t even turn the power down because they won’t believe us!!!!
Be interesting to how RSGB membership drops over this.
Hi John, it depends upon two factors :
1. What level of licence you have, hence the power level you can use.
2. The print out document when you do the assessment.
Yes, I do understand you point you can indeed have a 100 W transceiver and only run it at say 50W or even 10W ! It is essentially a “self declaration.”
73 Leslie G0CIB
Firstly, thanks for letting me join your forum, but sorry this has to be my first comment.
There are probably thousands of elderly hams in this country who haven’t got the luxury of a reasonable sized garden and rely on the hobby to stay in contact with freinds. Some people have no choice but put an antenna in the loft despite it perhaps being ‘bad practice’.
I find the timing of OFCOMS changes very poor at a time where many elderly people are feeling lonely. Our government like to promote the idea of mental ‘wellbeing’ but I do fear that when the HF rules come out, they will force many to give up.
I did wonder whether one solution to this is to grant ‘grandad/mum’ rights. After all most elderly licence holders are very experienced operators (?!).
I also don’t understand why the calculator shows the same separation distance for 100w as for 1w and why the separation distance goes up as the frequency decreases? BTW, if you type the numbers in for a mobile phone, shouldn’t it become lawcnot to hold the phone to our ears. ;-)
I being one of those who due to having a shared communal type garden can’t ensure a separation distance from my antenna. Anyone want to buy a ham nice radio setup?
Also, the calculator asks “Max transmission time in any 6 minute period”. I use my radio for about an hour a week, so what’s that work out to be?
The condition is only applicable when members of the public are exposed to EMF exceeding the limit. Are your neighbours in the garden 24 hours a day, seven days a week?
For your info : https://www.youtube.com/watch?v=kGcqTBH0_7w
73 g0cib