I wrote to the BBC under the "Freedom of Information Act" in 2009 to ask them to disclose the radiation patterns used by the transmitters in the UK. This information shows the level of signal reduction from each transmitter in each direction, as the signals are not always broadcast at their full power (the "ERP") in all directions.
The response, which I posted here on 5th September 2009 can be see here:
BBC Freedom Of Information - transmitter radiation patterns and these are now included in the transmitter pages on UK Free TV, as shown in this example:

Also provided was some information on the pre-switchover patterns for certain transmitters, see
BBC FOI transmitter data - first draft from 12th September 2009.
I recently wrote again to the BBC asking them to disclose the information for the masts that were "redacted" (withheld) in the original request. These masts are listed at the foot of this article.
The response from the BBC today is shown below:
British Broadcasting Corporation Room 2252, White City, 201 Wood Lane, London W12 7TS
Telephone 020 8008 2883 Fax 020 8008 2398 Email foi@bbc.co.uk
Information Policy & Compliance bbc.co.uk/foi
6 March 2012
Dear Brian,
Freedom of Information Act 2000 - RFI20120153
Thank you for your request under the Freedom of Information Act (the Act) of 9 February 2012, seeking the information which we had withheld from our earlier response to your previous request under the Act of 3 August 2009 (our reference RFI20091165).
In our reply to RFI20091165, we stated that we expected international negotiations regarding coordination of certain of the
antenna patterns which you had requested to continue until the end of 2012. I am advised, however, that
Ofcom has informed our spectrum planning team that these negotiations have not yet concluded and may in some cases still have some months to run.
Since we last wrote to you regarding this matter, it has also become clear that a further clearance of spectrum currently allocated to DTT is to be expected, for which international negotiations may start shortly. Therefore, I am afraid that it appears to us that negotiations surrounding these have not concluded.
For that reason, therefore, I regret that we must continue to withhold the data for these sites under the exemption in section 27(1) of the Act ("International Relations").
As set out in our response to RFI20091165, the exemption referred to above is a qualified exemption, which means that it must be tested against the public interest in favour of disclosure.
We note that for a number of transmitter sites (that is, all those marked as "Redacted" in the spreadsheet accompanying our last response to you), the exact radiation pattern that is to be employed is still subject to, or is likely to require, negotiations between HM Government (represented by Ofcom) and the equivalent administrations in these neighbouring countries.
The arguments in favour of disclosure are:
- the antenna systems used for television transmission are, in part, funded by public money through the BBC's transmission contracts with Arqiva and the public has an interest in understanding what that money has been spent on; and
- disclosure of the antenna radiation patterns would enable certain members of the public with specialist knowledge to gain a more accurate understanding of reception conditions in their area.
However, the arguments against disclosure of the characteristics of particular antenna systems are:
- disclosure of the antenna radiation patterns into the public domain could lead to these being available to foreign administrations, which would substantially weaken HM Government's negotiating position with respect to international frequency clearance;
- a weaker negotiating position for HM Government may lead to additional cost for the broadcasters (where antenna systems have to be re-built as a result of international coordination) and lower coverage for viewers (where antenna systems have to be restricted in order to protect foreign transmissions); and
- the BBC is required to provide coverage of its services on digital terrestrial television to a certain proportion of the population by the completion of switchover and a failure or suboptimal result from international co-ordination may harm the BBC's ability to meet this obligation.
Therefore, I am satisfied that in all the circumstances of the case, the arguments against disclosure outweigh the public interest in disclosure for some of the antenna radiation patterns.
Appeal Rights
If you are not satisfied with this response you have the right to an internal review by a BBC senior manager or legal adviser. Please contact us at the address below, explaining what you would like us to review and including your reference number. If you are not satisfied with the internal review, you can appeal to the Information Commissioner. The contact details are: Information Commissioner's Office, Wycliffe House, Water Lane, Wilmslow, Cheshire, SK9 5AF, telephone 01625 545 700 or see http://www.ico.gov.uk/
Yours sincerely,
Tom Everest
BBC Distribution
I am considering if making an appeal is the best course of action, or perhaps waiting until the end of 2012, when the mentioned negotiations may be complete.