Ofcom EMF risk assessment & UK SOTA (part 2)

Just received my formal email from Ofcom. Has it been published else where. I didn’t find it in the previous topic:

Dear Licence Holder,

We are writing to make you aware of some important changes that we are proposing to make to your Wireless Telegraphy Act licence(s) issued by Ofcom.

In February and October last year, we issued two public consultations on our proposal to formally require licensees to comply with the internationally agreed levels in the International Commission on Non-Ionizing Radiation Protection (ICNIRP) Guidelines for the protection of the general public from electromagnetic fields (EMF). We refer to these levels as the ICNIRP general public limits. In October, we also issued a Statement setting out our decision to formally require licensees to comply with the ICNIRP general public limits and we recently published an update on how we propose to implement that decision.

We are now writing to you to inform you of our proposal to vary the terms and conditions of your licence(s) to require you to comply with the ICNIRP general public limits. In accordance with the Wireless Telegraphy Act and your licence(s), we are giving you notice of our proposal by publishing a General Notice on our website.

We’ve put all the relevant information about our proposal including the General Notice on a dedicated EMF webpage Meysydd Electromagnetig (EMF) - Ofcom. Here you will find details of the licence variation process alongside the background to the changes and lots of FAQs to help you understand what our proposal means for you.

If, after reading the above information, you wish to make a representation to Ofcom in relation to our proposal to vary your licence(s), you have up until the 18 April 2021 to do so. However, if you do not wish to make a representation you do not need to take any action at this time. More information on the representation process can be found by visiting the Ofcom EMF webpage.

We will consider all representations before coming to a final decision on the variation of your licence(s). We will publish our final decision on the EMF page of our website by 18 May 2021. We will explain whether we have decided to vary your licence(s) to include the EMF condition. If your licence(s) has been varied we will send you an update of it or information on where a new version can be obtained from.

In future we intend to make greater use of General Notices published on our website and may not individually contact you to inform you that we have published one. We would therefore urge all licensees to regularly check the Ofcom website or subscribe to email spectrum updates by going to the following page on our website Subscribe to email updates - Ofcom.

If you have any questions about this change and what it means for you, further information can be found on the dedicated EMF webpage using the address provided above.

Yours faithfully,



This exact letter has gone out to all radio transmitter licensees in the UK, not just us radio amateurs. I have received the same letter in my role as senior air traffic engineer for my local airport and, surprisingly, another letter for the radios in my aircraft!

73, John/WGV


So what do we have to actually do ?

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Hi Allen,

Once the licence change has been implemented, we will have to be able to demonstrate that our station is being operated within the guidlines for exposure to RF. Measuring this would be very difficult and involve expensive equipment, so calculations have to be made based on antenna design and location, frequency band, power etc.

This would be pretty daunting for most of us to attempt on our own from scratch, but our national society (RSGB) is working to provide a spreadsheet for us to use, to make things easier.
They are also hoping to produce some “standard configurations”, so that if we can show that our station fits one of those, it is considered compliant. (all of this will have to be agreed / accepted by OFCOM of course)

Its a work in progress, and I should mention that they are liaising with the American national society ARRL, as they face simillar changes.

Read all about it here: EM Field Exposure - Radio Society of Great Britain - Main Site : Radio Society of Great Britain – Main Site

It’s probably worth becoming familliar with the subject - it’s not something that I have thought much about other than in the context of microwave comms…


[pedant mode on]

Can I point out it is Ofcom not OFCOM.

[pedant mode off]

Secondly I think it’s worth starting a book on when the first Ofcom inspection of a random amateur station will be. I’m plumping for the 15th of Never. Any other bets?


Thanks Adrian I downloaded the calculator from ofcom but all I get is a black screen

So basically Andy do we just ignore it ?

What do you think?

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Mmm, sorry, can’t help with that - it worked for me in Windows using OpenOffice, and on my Chromebook using Google Sheets.

To the same extent that we ignore any other licence terms, I guess…

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Suggest you use the RSGB Prototype version of the spreadsheet Alan as suggested in Radcom - I have done my calculations so far from 2m down to 20m with the 3 different antennae I use on those bands. I’m leaving 10 MHz and below until later, hoping that the RSGB provide the tools for the job which take in near field calculations. My 20m 400 watt legal limit example is attached as a photo - the spreadsheet needs MS Excel to run. You will need to take horizontal and vertical measurenents of your antennae situation and from these calculate the diagonal distances to neighbours gardens, rooms and the public space adjoining your site. The safe Ofcom separation distance for this example is 7.4m to someones head, assumed to be at 1.8m AGL. In my case the distance would be 13m to the persons head on my next door neighbours property (or 12m into the nearest room) so I comply with ICNIRP. I have not factored in sidelobe loss which varies from antenna to antenna although the RSGB suggest that could be added as a minus dB figure to help us in our calculations. It won’t be much for the Hexbeam as the forward gain is only around 4 dBd.

73 Phil

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… and for those operating with anything other than QRP on hill tops, you need to take a portable fence to keep the public away from your antenna.

I can see issues arising for activating as presumably adherence to the requirements applies in each and every situation. Take running something like 30 watts to a vertical antenna in the Trans-Atlantic S2S QSO event from a popular summit for example. People might, and indeed have in the past, come over to see what I am doing and stood within a few metres of the antenna. What does this mean for activating in general? Will verticals and inverted vee dipoles become restricted to QRP use only? Time to run a few scenarios through the program.

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ok Phil I installed excel and now have the screen that you have so will have a go later Thanks

And even touching it

I have even had to ask my son to stop grabbing the wire of my sloper endfed antenna while I was dealing with the pileup…


Phil on my 20m one it shows ofcom separation as 1.8m in pink , what does this mean please as my long wire is at least10-15 m away from anyone

Read the displayed notes ( black text on light green background) as shown in Phil’s picture.

I* have done Andy but why it displays as pink is beyond my comprehension , sorry but it just isn’t logical how my setup is not within limits

The most obvious answer is you have entered the numbers wrong. If you enter the numbers as Phil has you should get the same answer.

Look Andy I apologize for being a pain but my numbers can’t be the same as Phils as I can only use 50w

Like some others I have now reviewed my Home QTH set-up and a typical SOTA activation using the RSGB EMF assessment tool. Subject to relying on the Ofcom/RSGB EMF assessment tool’s results and not by any measurement, a typical SOTA activation (FT817ND, 5 watts o/p, linked dipole and 10m SOTA pole appears to be OK. NOTE: The Ofcom recommended separation is superceded by the Near field zone separation distance which is typically several times more but typically 10 - 13m. I have simply followed the Ofcom/RSGB assessment tool without questioning it efficacy (new word I picked up somewhere?)
However, I would suggest that every radio amateur in UK runs their own assessment as

  1. Your AR licence is about to be revalidated or not by Ofcom depending whether you can show you have done an assessment or not. (Around Nov 2021)
  2. Check your home QTH assessment. Mine was a surprise and only just works for a typical small installation. The assessment is an exercise in learning on what you may have assumed is ok or maybe not so?
    The assessment tool can be found on RSGB website (I think you have to be a member?)
    Good luck
    Rob G0HRT