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There is no single maximum speed for coaxial cable. It depends on what you mean by “speed”:
So, for a practical home-networking answer: good RG-6 coax can easily support gigabit-class data rates, and with modern cable-network technology it can support multi-gigabit speeds.
An electrical signal in coaxial cable travels as an electromagnetic wave, not as electrons physically moving from one end to the other. Its velocity is mainly determined by the dielectric material between the center conductor and shield.
The approximate propagation velocity is:
\[ v = \frac{c}{\sqrt{\epsilon_r}} \]
where:
Typical values:
| Cable dielectric type | Velocity factor | Approximate speed |
|---|---|---|
| Solid polyethylene coax | 0.66c | ~200,000 km/s |
| Foam polyethylene RG-6/RG-11 | 0.80c to 0.85c | ~240,000–255,000 km/s |
| Air-spaced / low-loss precision coax | 0.90c or higher | ~270,000 km/s+ |
This is the propagation speed, not the data rate.
The data rate depends on the electronics and modulation system, not just the cable.
Examples:
| Technology over coax | Typical / theoretical speed |
|---|---|
| Old Ethernet over coax, e.g. 10BASE2/10BASE5 | 10 Mbit/s |
| MoCA 2.0 | up to ~1 Gbit/s class |
| MoCA 2.5 | up to ~2.5 Gbit/s shared throughput |
| DOCSIS 3.1 cable internet | up to ~10 Gbit/s downstream theoretical |
| DOCSIS 4.0 | up to ~10 Gbit/s downstream and several Gbit/s upstream |
| Advanced/lab HFC systems | potentially 10+ Gbit/s aggregate |
For normal home use, the practical limit is often not the coax itself, but:
A poor splitter or corroded connector can reduce performance far more than the coax type itself.
Coax is an RF transmission line. It can carry signals from DC up to some high-frequency limit, but loss increases as frequency rises.
Typical practical ranges:
| Coax type | Common use | Practical frequency range |
|---|---|---|
| RG-59 | CCTV, older TV cabling | hundreds of MHz to ~1 GHz |
| RG-6 | TV, cable internet, satellite | ~1–3 GHz typical |
| RG-11 | long cable runs, lower loss | ~1–3 GHz typical, depending on construction |
| Semi-rigid RF coax | lab/microwave | tens of GHz |
| Precision coax with 1.0 mm connectors | RF instrumentation | up to ~110 GHz |
Higher frequency does not automatically mean higher data rate, but more usable bandwidth usually allows more data if the modulation and noise conditions are suitable.
The theoretical channel capacity is governed by the Shannon-Hartley relationship:
\[ C = B \log_2(1 + SNR) \]
where:
This means coaxial cable can carry very high data rates if it has enough usable bandwidth and good signal quality.
Modern cable networks are still extracting more capacity from existing coaxial infrastructure. The main trend is not changing the cable, but improving:
DOCSIS 4.0 is designed to push coax networks toward multi-gigabit and near-symmetrical service, especially by expanding usable spectrum and improving upstream capacity.
However, for very long-distance or ultra-high-capacity links, fiber optic cable is superior because it has:
That is why modern networks increasingly use fiber closer to the customer, with coax often used only for the final in-building or neighborhood segment.
If you are asking for a real installation:
Use:
Good RG-6 is normally suitable for gigabit and multi-gigabit cable internet, assuming the provider and modem support it.
Use:
MoCA 2.5 can provide very good real-world performance, often suitable for replacing or supplementing Ethernet where pulling CAT6 is difficult.
You must specify:
At high frequencies, connector choice can be as important as the cable itself.
The “maximum speed” of coaxial cable depends on context:
In practical terms: coaxial cable is not inherently limited to 100 Mbit/s or 1 Gbit/s. With good cable and modern electronics, it can support multi-gigabit data rates.