Use a coax cable loss chart to choose cable by impedance, operating frequency, and total run length—not by the RG number alone. For most television, satellite, and cable-modem installations, choose a 75-ohm cable such as RG-6; use RG-11 for longer runs and a suitable 50-ohm cable for radio-frequency equipment.
Calculate the complete path from source to receiver. Cable attenuation, connectors, barrels, a coax cable wall plate, splitters, and poor terminations can all reduce signal level or increase mismatch loss.
Coax comparison chart: Which cable fits your system?
Match 50-ohm and 75-ohm systems to their common uses
Impedance must match the equipment and system. A 75-ohm path is standard for broadcast television, satellite TV, cable TV, antennas, and most residential broadband. A 50-ohm path is common in two-way radio, cellular, Wi-Fi infrastructure, test equipment, and other RF systems. A connector that physically fits does not make a 50-ohm and 75-ohm path electrically equivalent.
Compare RG-6, RG-59, RG-11, and 50-ohm coax by size, shielding, flexibility, and use
- RG-59: A slim, flexible 75-ohm cable, typically about 6 mm in diameter. It is useful for short CCTV, baseband video, and legacy installations, but its smaller conductor usually produces more high-frequency loss than RG-6. Shielding varies widely, so check the construction.
- RG-6: A roughly 7 mm 75-ohm cable and the usual residential choice. Dual, tri, and quad-shield versions improve protection from interference. It is flexible enough for wall boxes and supports TV, satellite, antenna, and modem runs.
- RG-11: A larger, approximately 10 mm 75-ohm cable with lower attenuation over long distances. Its thicker dielectric and conductor make it less flexible and harder to terminate, but it is useful for long feeder runs.
- 50-ohm coax: RG-58 is relatively thin and flexible for short RF connections, while low-loss types such as LMR-400 are much larger, better shielded, and less flexible. Select the cable from the equipment impedance and the required frequency range.
These are representative families, not guaranteed performance grades. Compare the manufacturer’s diameter, shielding coverage, bend radius, connector compatibility, and attenuation values for the exact cable.
Coax cable loss chart: How do you read attenuation by frequency and length?
Read dB per 100 feet or 100 meters at the operating frequency
Find the attenuation row or column for the operating frequency, then apply the listed value to the installed cable length. Loss normally increases with frequency, so use the highest important operating frequency when designing a broadband run. Do not compare a value at 100 MHz with another cable’s value at 600 MHz.
For a chart showing 6 dB per 100 feet at 600 MHz, a 60-foot cable contributes:
6 dB × 60 ÷ 100 = 3.6 dB
If the chart uses dB per 100 meters, use the length in meters. Manufacturer charts may differ because of conductor size, dielectric, shielding, temperature, and test conditions. Use the chart for the exact cable, and keep frequency and distance units consistent.
Coax cable wall plate: Which coupler should you choose?
Treat the plate and barrel as signal-path components, not transparent fittings
A wall plate usually contains an F-female-to-F-female coupler or a short internal cable. That coupler has insertion loss, return loss, and a maximum rated frequency. It is not electrically transparent merely because both connectors fit. A cheap or poorly shielded part can add loss, impedance discontinuity, or interference to an otherwise good cable.
Check F-type fit, impedance, shielding, and termination quality
For a 75-ohm TV or satellite run, choose a 75-ohm F-type wall plate rated above the highest system frequency. Prefer a shielded coupler with a secure threaded connection and a solid mounting design. Confirm that the cable’s solid or stranded center conductor suits the connector. Compression or properly installed crimp connectors usually provide more consistent shielding than loose push-on fittings.
Do not use a 75-ohm F plate as a substitute for the correct 50-ohm RF panel connector. Also check whether the wall box allows the cable’s bend radius; forcing RG-6 or RG-11 into a tight box can deform the dielectric and increase mismatch loss.
How do you estimate and test the complete installed run?
Add cable, connectors, barrels, plate, splitter, and installation workmanship loss
Use this estimate:
Total path loss = cable loss + connector loss + barrel loss + wall-plate loss + splitter loss + workmanship allowance.
For example, a 60-foot RG-6 run at 600 MHz might contribute 3.6 dB. Add four connectors at 0.15 dB each, a barrel at 0.2 dB, a wall plate at 0.3 dB, a two-way splitter at its marked 3.5 dB, and 0.5 dB for workmanship or minor installation uncertainty:
3.6 + 0.6 + 0.2 + 0.3 + 3.5 + 0.5 = 8.7 dB total.
Use manufacturer specifications for actual components. Count every connector and inline adapter, and include unused splitter ports only when the splitter design specifies a relevant termination loss.
Test signal level and insertion loss at both ends of the run
- Record the source signal level at the operating frequency with the wall plate and splitter bypassed.
- Measure at the far end through the cable alone, if accessible, and compare the change with the calculated cable loss.
- Install the connectors, barrel, wall plate, and splitter one at a time. Record the additional insertion loss after each component.
- Inspect for loose fittings, braid strands touching the center conductor, crushed cable, sharp bends, and poorly seated connectors if measured loss exceeds the estimate.
A complete installed-run measurement should agree reasonably with the calculation across the service band. A sharp frequency-specific drop often indicates a damaged cable, bad termination, or mismatched coupler rather than ordinary cable attenuation.
