TV Coax Cables
and Signal Loss

• TV Cable Types
• Signal Loss
  Loss Calculator
• Signal Splitters
• Connectors
• Coax/Twin-lead Adapters
• Antenna to TV Loss Calculator

Three types of coax cable (RG-6, RG-11, RG-59) can be used to connect an antenna to televisions. All TV coax cables have a 75 ohms (Ω) impedance and use F-type male connectors. Cable signal loss mainly depends on cable type, length, and signal frequency (RF channel). Signal splitters cut signals in half, the more times it's split the lower the signal. Connectors and adapters introduce a small loss.

RG-6 coax cable
This cable is the industry standard for home reception. RG-6 is available with 2, 3, or 4 layers of shielding. Three or four layers has better immunity from interference and is more sturdy and durable, but is a little more expensive and less flexible than dual shield. Outside cables should be quad shield (4 shield layers).

RG-11 coax cable
This cable can be used if signal loss is a problem, typically a long cable run. The advantages of RG-11 are it has the least loss, and is available with 2, 3, or 4 layers of shielding. It can also carry high power signals. The disadvantages are it's more expensive, less flexible, bigger and heavier. This cable is primarily designed for high power transmissions and long cable runs.

RG-59 coax cable
This cable can be used, but is a little more lossy and has only a single layer of shielding. RG-59 is usually used indoors for raw video signals (recorders, games, etc.). RG-59 was used for over-the-air TV (and cable systems) before RG-6 became common.

Twin-lead cable
This cable is sometimes called flat or ribbon cable, and should be replaced. Twin-lead works well for VHF frequencies (RF 2-13) and is especially good at the VHF-Lo channels (RF 2-6), but has no shielding and is not suitable for UHF channels (RF 14 and higher). Some twin lead cables do not weather well and degrade (more signal loss) with time.

All cables have some signal loss. Loss is measured in power decibels (dB's). The longer the cable the greater the loss. Also, the higher the frequency (the higher the RF channel), the greater the loss. RF channels in the VHF Frequency Band have noticeably less loss than channels in the UHF band.

Cable Signal Loss depends on;

• Cable Type
• Cable Length
• Signal Frequency

Cable Characteristic Impedance is in ohms ( Ω ), and is the ratio of the signal electric to magnetic field. The RG in cable type stands for "Radio Guide", and is widely used to describe cable performance. RG designations were developed by the military during World War II.

A coax cable Signal Splitter is used to connect to multiple TV's and devices. The more the signal is split (output ports) the greater the signal reduction. A 2 port splitter cuts the signal by a little more than half (-4 dB), equivalent to adding about 70 feet of cable.

Splitter and wall output ports that are not used should be terminated with a 75 ohm load or termination.

Two cables can be connected using a female-to-female connector, also called a barrel. Television wall plates use barrel connectors. Coax ground blocks are barrel connectors with a port to connect / run a ground wire. Right angle connectors (female-to-male) can be useful connecting to televisions and antennas with limited space.

All connectors introduce a small signal loss, about -0.5 dB.

Some older antennas and televisions have a twin-lead connection and need an adapter to connect to a coax cable. A coax-to-twin-lead adapter (75/300 Ω) is an impedance MATCHING NETWORK (circuits) or a BALUN (ferrite transformer) that matches 75 ohm coax to 300 ohm twin-lead. Adapters work both ways (bi-directional), signals go from coax to twin-lead or twin-lead to coax. Adapters introduce a small signal loss that increases with frequency (RF Channel).

Estimate cabling loss from the antenna output port to a television based on cable type, frequency band or RF channel, cable length, and the number and type of signal splitters, connectors and adapters.

Also see Booster / Distribution Amplifiers.

OTA DTv TV Coax Cables and Signal Loss