UKThe 700 MHz clearance, and your aerial
Television left the top of the UHF band in 2020. Channels 49–60 went to mobile, every transmitter using them moved down into 21–48, and a great deal of aerial advice written before that is still online and still confident.
How to spot advice that predates it
A UK television channel number above 48 is the tell. Nothing has been transmitted above C48 since 2020, so any page, forum post or aerial listing quoting one is describing the band as it was.
More detail
We can put a number on how much that matters. Aerial group is a statement about channels: move the channels and the group moves with them, which is why a stale channel table and a wrong aerial group are the same mistake. Compared against the Wolfbane Cybernetic DTT predictor, its group agrees with Ofcom's on 97.7% of transmitters where its channel table is current and on 23.8% where it is stale. [V] The group column tracks the channel column that exactly — which is what makes the disagreement a measure of the clearance rather than of a naming convention.
What an aerial group is
A grouped aerial is tuned to part of the band instead of all of it. Ofcom publish a group for each transmitter, and it is the answer to “what will work here” — not a preference, the channels that site actually uses.
| Group | Channels | |
|---|---|---|
| A | C21–37 | the low end of the band |
| B | C35–53 | the middle |
| K | C21–48 | wideband across the whole post-clearance band |
More detail
K is the post-clearance wideband: it spans everything still in use, so it works at every transmitter in the country. A grouped aerial of the same size concentrates the same elements over a narrower span and so has more gain inside it [I] — which is the trade, and it only pays if the group is the right one. The older C/D and E groups covered channels above 48 and are now aimed at frequencies that carry no television.
The lookup states the group for the transmitter it picks for you, from Ofcom's column rather than from our model. Where two transmitters are worth considering it states both, because they are not always the same group.
What Ofcom's data actually says
1,127 masts publish an aerial group. [V]
| Group | Masts | Share |
|---|---|---|
| A | 538 | 47.7% |
| B | 475 | 42.1% |
| K | 112 | 9.9% |
2 publish more than one, because Ofcom hold them as separate rows that disagree. Those are shown as both rather than resolved to one — there is nothing in the data that says which row is right.
More detail
Only about a tenth are wideband, which reads as though most of the country needs a grouped aerial and is not what it means: a wideband works everywhere, and the group is what a correctly-grouped aerial would have to be to beat it. The figure to take from the table is that A and B are close to evenly split, so there is no group that is usually right.
Filters and amplifiers
Equipment sold as “4G filtered” before about 2013 filters at 800 MHz, and does nothing about the 694–790 MHz band that became mobile in 2020. [I]
More detail
Interference from a mast in that band looks like an ordinary weak signal: blocking, or a multiplex missing entirely. The distinguishing feature is that it does not follow the weather and does not improve with a better aerial, because the problem is arriving at the amplifier rather than at the aerial.
Where this leaves you
Look your postcode up — it names the transmitter, its group, its polarisation and which way to point. Or start from the symptom if something has stopped working and you do not yet know what.