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TV aerial cable: IEC, F connector and 75 ohms
A coaxial aerial cable looks simple: a centre conductor, insulation, a braided shield and an outer jacket. Choosing one on length alone, or on the rough shape of the connector, causes plenty of problems. A home installation carries terrestrial television (DTT), cable television and satellite, and they do not always use the same termination.
To get it right you have to check three things: the service you want to connect, the connector on each device and the impedance of the cable. In home television that impedance is normally 75 ohms. The most common connectors are IEC for TV/DTT and threaded F for satellite.
IEC and F: similar in purpose, different in use
The IEC connector, also called the TV aerial connector, is the round one that pushes into place. You will often find it on wall sockets, televisions, DTT receivers and some radio equipment. It can be male, with a visible centre pin, or female, with a centre socket.
The F connector is recognisable by its thread. Rather than carrying a separate pin, it normally uses the coaxial cable's own centre conductor as the contact. It is common on satellite installations, SAT set-top box inputs, dish LNBs, splitters and certain cable or broadband equipment.
Do not decide on the word "aerial" alone. A socket marked TV normally uses IEC, while one marked SAT normally carries F. Mixed TV/R/SAT wall plates also exist. The label on the port and its physical shape matter more than the commercial name of the device.
If you need to compare terminations, lengths or adapters, the aerial cables and adapters section lets you narrow the choice once you have checked the actual connectors in the installation.
What 75 ohms means
The 75 Ω figure does not describe the resistance a multimeter would read from end to end. It states the characteristic impedance of the cable at radio frequencies. That property depends on the geometry of the conductor, the dielectric and the shielding.
A television chain is normally designed to work at 75 Ω: cable, sockets, splitters, amplifiers and equipment inputs. Introduce a component with a different impedance and mismatches appear. Part of the signal is reflected instead of continuing towards the receiver. Over short runs you may not notice it, but an installation with marginal signal, long cable runs or several splitters can lose headroom and suffer dropouts or pixelation.
50 Ω coaxial is used in other fields, such as certain radio and data installations. It may carry connectors that look compatible with some equipment, but that does not make it a good choice for TV. For a home aerial connection, look for the 75 Ω rating and do not assume that any coaxial will do.
Male and female: check both ends
Gender refers to the physical contact, not to the device that sends or receives the signal. On IEC, the male has a pin and the female has a socket. On F, male normally means the connector with a nut that screws onto a female F socket on the equipment.
A male-to-female IEC cable is common between the wall socket and the television, but it is not a universal rule. An installation may need male-to-male, female-to-female or an adapter. Before you buy, look at both ports and note what has to fit into each one.
As a format reference, a 75 Ω coaxial aerial cable with male-to-female termination matches the usual wall socket to TV input arrangement, provided the gender and the IEC type match both connectors.
Quick decision table
| What you can see | Likely termination | What to check before choosing |
|---|---|---|
| TV wall socket and the ANT IN input on the television | IEC | Gender of both ends and length |
| DTT receiver output to the TV | IEC | Whether each port needs male, female or a combination |
| SAT socket to a satellite set-top box | Male F on the cable | Thread, coaxial diameter and routing through trunking |
| Dish LNB to the receiver | Male F at both ends | Outdoor use, sealing and total run length |
| TV/R/SAT wall plate | IEC for TV/R; F for SAT | Exact label on each output |
| Installed cable whose termination differs from the equipment | IEC/F adapter or a different cable | Direction, gender and the losses you add |
Length, shielding and assembly quality
Shielding protects the signal from interference and also reduces what the cable radiates. A braid with good coverage, backed in many cables by a foil layer, tends to behave better in areas with routers, power supplies, motors or electrical runs nearby. Even so, excellent shielding will not make up for a badly fitted connector or a broken conductor.
Avoid tight bends, crushing the cable under furniture and pulling on the connectors. Outdoors, the cable and the joints must be rated and protected against water and sunlight. An exposed F connector is not weatherproof simply because it is screwed on.
Common mistakes when installing aerial cable
- Confusing TV with SAT. DTT normally arrives over IEC and satellite over F. An adapter changes the shape, but it does not turn a DTT signal into a satellite one, or the other way round.
- Buying on the gender of one end only. You have to check the socket and the receiver. Photos of the connector help more than remembering "I think it was male".
- Using 50 Ω coaxial. It can carry the signal, but it breaks the matching a 75 Ω network is designed around.
- Chaining adapters unnecessarily. Every joint adds a possible point of looseness, oxidation or loss. A correct end-to-end termination is preferable.
- Blaming the cable for every fault. Pixelation can also come from a misaligned aerial, excessive signal, an overloaded amplifier, a faulty splitter or a problem in the communal system.
- Stripping an F connector badly. A single strand of braid touching the centre conductor can cause a short circuit. On satellite, the receiver may also power the LNB through the coaxial itself.
Checks before you close up the installation
With the equipment switched off, confirm that no braid strands are touching the centre conductor. Tighten the F connectors until they are firm, without forcing the port, and push the IEC connectors fully home. Then check signal level and quality in the television or receiver menu. Quality is usually more useful than a level percentage on its own.
Frequently asked questions
Can I use an IEC to F adapter?
Yes, when all you need is to adapt the physical termination and the signal is compatible with the destination port. The adapter does not turn DTT into satellite, nor does it change frequencies, power feed or protocols.
Does a thicker cable always receive better?
Not necessarily. Diameter can be linked to lower losses, but the dielectric, the shielding, the connectors and the frequency matter too. Compare attenuation figures and the intended use.
How do I know whether my socket is TV or satellite?
The TV output is normally push-fit IEC and the SAT output is normally threaded F. On a multi-output plate, check the TV, R and SAT markings. If there are no labels, check the installed wall plate before connecting a receiver that feeds power up the coaxial.
Do 75 Ω and 75 ohms mean the same thing?
Yes. Ω is the symbol for ohm. In this context it states the characteristic impedance of the coaxial system, not the DC resistance of the cable.
Does pixelation mean I need a new cable?
Not always. Try the connections first, then a patch lead you know is good, and the quality indicators. If several neighbours have the same fault, the cause may be in the aerial or the communal headend.