TV Coaxial Cable Guide: Why Cable Quality Matters

Coaxial cable quality genuinely affects TV reception — but not the way “HD cable” marketing implies. A digital signal either arrives intact or it doesn’t; no cable makes the picture sharper. What good cable (double-screened, copper-cored WF100 or CT100 grade) actually does is lose less signal over the run and shut out interference, which is the difference between a stable picture and break-up. Cheap single-screened “contract” coax is behind a large share of the reception faults we see.

What coaxial cable is

Coax is the round cable running from your aerial or dish to the TV. Cut one open and there are four layers, working outwards: a centre conductor (the signal path), a dielectric (an insulating foam or air-spaced layer that keeps the conductor exactly centred), the screen (a foil wrap and/or a woven copper braid that keeps your signal in and the world’s radio noise out), and the outer sheath protecting it all from weather.

The “co-axial” name just means the conductor and screen share the same axis. That geometry is the whole trick: it gives the cable a consistent 75-ohm impedance (the electrical characteristic TV equipment is designed around) and lets the screen act as a continuous shield around the signal. Every quality difference between cables comes down to how well those layers are made.

The “HD cable” myth

Packaging that promises a “sharper HD picture” from a premium cable is selling you a misunderstanding of how digital TV works. Freeview arrives as DVB-T/T2 (the UK’s digital terrestrial broadcast standards) — a stream of encoded data, not a picture. Your TV’s error correction either recovers that data perfectly, in which case you get exactly the picture the broadcaster transmitted, or it can’t, in which case you get blocking, freezing or nothing. There is no in-between where a better cable adds detail. A £3/metre cable and a £30/metre cable that both deliver the data cleanly produce identical pictures.

So why does cable quality matter at all? Because of what happens when the data doesn’t arrive cleanly. Poor cable loses more signal along the run and lets interference in, pushing a marginal signal over the “digital cliff” — the point where error correction gives up. Good cable buys you margin. That’s the honest claim, and it’s worth paying for; “HD-quality picture enhancement” is not.

WF100/CT100 vs cheap contract coax

The benchmark cables for UK aerial and satellite work are WF100 (Webro) and CT100 (Cavel) and their direct equivalents. What defines the grade:

Solid copper centre conductor — low resistance, and it carries the DC power some setups send up the cable (masthead amplifiers, satellite LNBs) without voltage drop.
Double screening — a copper foil wrap plus a dense copper braid over it. This is the layer that matters most in 2026, for reasons covered below.
Air-spaced or foam dielectric built to hold tight impedance tolerances.

The stuff to avoid is generically called contract coax or “low-loss” bargain cable, and much of what’s sold cheaply as RG6 sits in the same bracket: a copper-coated steel centre conductor, a single sparse aluminium braid, and loose manufacturing tolerances. (RG6 is a US specification family — decent RG6 exists, but the £15-a-drum reel at the DIY shop is not it.) It costs a pound or two less per metre, and it is the single most common hidden cause of the flaky reception jobs installers get called to. The CAI (Confederation of Aerial Industries — the UK trade body) benchmarks cables for exactly this reason; WF100-class cable carries its approval, contract coax generally doesn’t.

	WF100 / CT100 class	Cheap contract / bargain RG6
Centre conductor	Solid copper	Copper-coated steel
Screening	Foil + dense copper braid	Single thin braid or sparse foil
Loss at UHF (per 10 m, approx.)	~1.5–2 dB	~2.5–3 dB+, inconsistent
Interference rejection	Very good	Poor
Powers masthead amps / LNBs	Yes	Marginal (steel core, voltage drop)
Satellite suitable	Yes	Often not
Typical price difference	—	Saves ~£10–£20 on a whole install

That last row is the point: on a £150–£250 aerial installation, the saving from cheap cable is trivial and the performance cost is not. It’s one of the corner-cuts we describe in the cheap aerial installation myth.

Attenuation: what long runs cost you

Every metre of coax loses signal — attenuation rises with frequency, so UHF TV frequencies (roughly 470–700 MHz since the 700 MHz band moved to mobile in 2020) suffer more than radio does, and satellite frequencies more still. Working figures for WF100-class cable: around 1.5–2 dB per 10 metres at UHF, roughly double that at satellite frequencies.

For context, an aerial-to-TV run in a typical two-storey house is 10–20 metres, costing 2–4 dB — rarely a problem. But a 35-metre run to a garden office, plus a couple of joints and a splitter (each joint ~0.5 dB, a two-way splitter ~4 dB), can total 12 dB or more, which in a moderate-signal area is enough to fall off the cliff. Cheap cable makes every one of those numbers worse. This is also why the fix for a long run is sometimes a properly sited amplifier rather than thicker cable — see signal booster vs amplifier for when each applies.

Terrestrial and satellite make different demands, too. A satellite installation pushes 950–2150 MHz down the cable and sends power up it to the LNB (the receiving unit on the dish arm), so copper-cored double-screened cable isn’t optional — cheap steel-cored coax that limps along for Freeview will often fail outright for Sky or Freesat.

Screening: the interference problem that got worse

The screen’s job is to keep external radio energy out of the cable, and the UK has made that job harder. Since the 700 MHz clearance completed in 2020, the frequencies directly above the TV band belong to 4G and 5G mobile networks. A nearby mast — or a phone transmitting inside your house — can push signal straight through a poorly screened cable, corrupting the data underneath the wanted signal.

Impulse noise is the other classic: short bursts of radio energy from fridge compressors, central-heating thermostats, LED dimmers, and vehicle ignition. Through single-screened coax these arrive as momentary picture freezes and blocking that seem random and are miserable to diagnose, because the cable looks fine and the signal strength reads fine — it’s the signal quality that’s being trashed.

Double screening (foil plus dense braid) suppresses both dramatically. If your break-up correlates with the boiler firing or with evenings on the sofa near your phone, screening is the prime suspect — our 4G and 5G Freeview interference guide covers the diagnosis and where a filter helps.

Connectors and wall plates

Two connector families live on UK TV cabling. The Belling-Lee plug is the familiar push-in aerial plug, essentially unchanged for a century — fine for the final flylead into the TV. The F-connector screws on, grips the cable’s screen a full 360°, and maintains screening integrity through the joint — it’s what satellite kit uses exclusively and what good installers now use everywhere they can: aerial terminals, amplifiers, splitters, wall plates. A poorly assembled Belling-Lee with a stray braid whisker is a little interference aerial in its own right.

Wall plates deserve a mention because the cheap “capacitor-coupled” ones quietly eat several dB and block the DC power that masthead amplifiers need. A screened, non-isolated F-type or direct-coupled plate costs a couple of pounds more and doesn’t sabotage the run. Every joint in the chain is a small loss and a potential screening breach — the best installations have the fewest joints.

When re-cabling fixes reception

Re-cabling is the unglamorous repair that outperforms expectations. It’s the likely answer when:

The aerial is healthy and correctly aligned (check which way your aerial should point) but signal quality readings are poor — see how to check signal strength.
Reception worsens in rain: water has got into the cable or an outdoor joint, corroding the conductor. Wet, corroded coax can lose several times its rated attenuation, and no amount of retuning fixes it.
Break-up correlates with appliances, phones or passing traffic — screening failure.
The existing cable is decades-old brown coax from the analogue era, which was often single-screened and is now perished.

A straightforward re-cable of one run, done alongside other work, typically adds a modest amount to a repair visit — far less than replacing an aerial that was never the problem. If channels vanished suddenly rather than degrading, start instead with Freeview signal disappeared to rule out transmitter work.

If your reception problems sound like a cabling fault — weather-dependent break-up, interference patterns, an ageing install — get in touch with your postcode. We route enquiries to local installers who work with benchmarked cable as standard, and who will test the run you have before selling you the run you might not need.