TV CABLE TYPES |
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.
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 / satellite systems) before RG-6 became common.
Twin-lead
cable
This cable is sometimes called flat or ribbon cable, and should be replaced with coax.
Twin-lead has 300 ohms impedance and uses blade connectors.
Twin-lead works well for VHF frequencies (RF 2-13) and is especially good at the VHF-Lo channels (RF 2-6), but 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.
SIGNAL LOSS |
All cables have some signal loss. Loss depends on cable type, length, and RF channel signal frequency. The longer the cable and the higher the frequency (the higher the RF channel), the greater the loss. Radio frequency channels 2-13 in the VHF band have noticeably less loss than RF channels 14 and above in the UHF band. Loss is measured in decibels (dB's).
Loss Depends on; |
• Cable Type • Cable Length • RF Channel |
TV Coax Cables | |||
VHF / UHF (RF 2 - 69) 75 ohms (Ω) Impedance F-type male connectors |
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Coax Type |
Loss
dB / 100 ft |
Shield Layers |
Primary Use |
---|---|---|---|
RG-6 | -5 dB | 2, 3, or 4 | TV Reception |
RG-11 | -3 dB | 2, 3, or 4 | High power signals or long cable runs |
RG-59 | -6 dB | 1 | Raw Video or TV Reception |
Twin-lead Cables | |
VHF (RF 2 - 13) 300 Ω Impedance Blade connectors |
|
Loss dB / 100 ft |
Primary Use |
---|---|
-1 dB ( VHF-Lo ) -4 dB ( VHF-Hi ) |
VHF Signals |
Coax Cable Loss Calculator
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SIGNAL SPLITTERS |
A coax cable Signal Splitter is used to connect to multiple TV's and devices. A two port splitter cuts the signal in half, equivalent to adding about 70 feet of cable. The more the signal is split (output ports) the greater the signal reduction.
Output Ports |
Loss per Port |
---|---|
2 | -4 dB |
3 | -6 dB |
4 | -8 dB |
8 | -12 dB |
Splitter and wall output ports that are not used should be terminated with a 75 ohm load or termination.
CONNECTORS |
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.
COAX to TWIN-LEAD ADAPTERS |
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).
Frequency Band |
RF Channel |
Loss dB |
---|---|---|
VHF-Lo | 2 - 6 | -0.2 |
VHF-Hi | 7-13 | -0.4 |
UHF | 14 | -1.0 |
UHF | 36 | -1.4 |
UHF | 40 | -1.5 |
UHF | 69 | -2.0 |
SYSTEM LOSS CALCULATOR |
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.
Antenna-to-TV Signal Loss | ||||||||||||
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Also see Booster / Distribution Amplifiers.
OTA DTv
TV Coax Cables and Signal Loss |