Short answer: at the transmitter that serves your area, along a bearing you can work out from your location and the transmitter’s, with the aerial’s rods set horizontal or vertical to match that transmitter. The catch is that the right transmitter is often not the nearest one, because the difference between a 200 kW main station and a 7 W relay dwarfs the difference between 10 km and 30 km.
This guide explains how the direction is worked out, how to choose the transmitter, and the two things that go wrong more often than the pointing.
Where the answer comes from
Ofcom publishes the parameters of every UK terrestrial TV transmitter: its position, height, radiated power, polarisation, and the channels and multiplexes it carries. Aerial Aligner bundles that dataset, 1,130 sites including the Local TV and Northern Ireland multiplexes, and works entirely from it, offline.
Given your position, from a postcode or GPS, the app does three things for each site:
- Distance, along the great circle between the two points.
- Bearing, the forward azimuth from you to the transmitter, in degrees clockwise from true north. That is the direction the aerial points.
- A signal estimate, from the site’s radiated power and the distance, using a calibrated path-loss model. The result is a band: Strong, Good, Marginal or Poor.
Sites are then ranked by that estimate, not by distance. The bands are a planning estimate for a roof-height aerial, calibrated against a published UK coverage predictor at a set of test postcodes. They are a guide to which site to try first, not a promise about your loft.
Worked example: Fleet, Hampshire
For a postcode in Fleet, the nearest site is a relay called The Bournes, about 10.6 km away, radiating 7 watts. It is not the answer. Ranked by the app’s estimate:
| Site | Power | Distance | Bearing | Polarisation | Multiplexes |
|---|---|---|---|---|---|
| Hannington | 50 kW | 29.6 km | 273° (W) | Horizontal | 8 |
| Guildford | 2 kW | 16.5 km | 116° (ESE) | Vertical | 7 |
| Crystal Palace | 200 kW | 53.7 km | 74° (ENE) | Horizontal | 7 |
| Midhurst | 20 kW | 31.8 km | 165° (SSE) | Horizontal | 6 |
Hannington is nearly twice as far as Guildford and three times as far as The Bournes, and it is still the site to point at: 50 kW into a clear westerly path beats 2 kW from the south-east and 7 W from a relay designed for a single valley. It also carries eight multiplexes where the relay carries three.
So the aerial in Fleet points a little north of due west, with the rods horizontal.
Match the polarisation, or nothing else matters
Every transmitter radiates with its signal polarised either horizontally or vertically, and a few of the biggest sites do both. Your aerial’s rods have to be set the same way: horizontal rods for a horizontal transmitter, vertical for vertical. Get it wrong and a good signal drops to nearly nothing, whatever direction you point.
The pattern in Ofcom’s data is strong. Of the 50 UK sites transmitting at 10 kW or more, 48 are horizontal. Of the 1,042 sites under 1 kW, 939 are vertical. Main stations are horizontal; relays are vertical; the exceptions exist, which is why the app shows the polarisation for the specific site you choose rather than leaving you to assume.
If you are switching from a relay to a main station, or the other way, the rods almost certainly have to be turned through 90°.
Check the channels against the aerial
Every site in Ofcom’s current dataset uses UHF channels between 21 and 48. Older aerials were built for a “group” of channels, and some were built for channels that no longer carry television. A wideband aerial covers the whole range. If you are reusing an existing aerial, compare the channel numbers of the site you are pointing at, which the app lists, against what the aerial was made for, and if it was installed before the last retune, treat its group with suspicion.
Multiplexes: why some channels are missing
Freeview is not one signal. It is a set of multiplexes, each carrying a bundle of channels, and not every site carries every multiplex. The three public service multiplexes reach nearly everywhere; the commercial ones reach most main stations and few relays. In the Fleet example, the relay carries three multiplexes and Hannington carries eight.
If you can get BBC One but not a channel further down the list, the site you are on may simply not transmit it. Pointing at a main station that carries the missing multiplex fixes that; a bigger aerial pointed at the relay does not.
Pointing it
The bearing is measured from true north. A phone compass reads magnetic north unless corrected, and in the UK the two are currently within a couple of degrees of each other, which is inside the tolerance of a directional aerial. Aerial Aligner uses the phone’s true heading where it is available and shows the deviation from the target live, with the dial turning green when you are on it.
Stand where the aerial will be, or as near as you can, and turn until the compass shows the target. Then look along that line. A directional aerial wants a clear path; a hill, a large building or a block of flats in the way will cost more than a few degrees of misalignment ever will. If the direct line is blocked, the second-ranked site with a clear path is often the better choice, and that is the real reason the app shows a ranked list rather than a single answer.
Caravans, boats and moving house
The same rules apply at every pitch. Rank, check polarisation, point, and check which multiplexes the site carries before deciding the box is faulty. Aerial Aligner works offline, so it does the ranking in a field with no signal at all.
Sources and scope
Transmitter positions, powers, polarisations, channels and multiplexes are from Ofcom’s published transmitter parameters, as bundled in Aerial Aligner and refreshed from Ofcom’s data. The signal bands are the app’s own calibrated estimate and are not an Ofcom coverage prediction. Freeview’s own coverage checker is the reference for what a given address is expected to receive.
Dataset facts and the worked example were computed on 11 September 2026 from the Ofcom transmitter data bundled in Aerial Aligner 2.0. Plan CD is not affiliated with Ofcom, Freeview or any broadcaster.