Quick answer: Coaxial cable is a shielded electrical cable with a copper core that carries TV, internet, and RF signals. It’s the cable behind your TV and cable modem — thicker than Ethernet, with a single center pin connector.
Coaxial cable — or coax — has been running through walls, attics, and utility poles for over 70 years. You’ve seen it: the thick, round cable that screws into the back of your TV or cable box. Despite Ethernet taking over local networks, coax remains the backbone of cable TV, broadband internet, and security camera systems worldwide.
This guide covers everything you need to know: how it’s built, the different types, where it’s used today, and how it compares to modern alternatives.
How Coaxial Cable Is Built
Coax gets its name from its concentric (“co-axial”) design — every layer shares the same central axis. That structure is what gives it its signal-carrying ability and interference resistance.
- Inner conductor: A solid or stranded copper wire at the center. This is the signal path.
- Dielectric insulator: A non-conductive layer (usually polyethylene foam) separating the conductor from the shield. Its thickness determines the cable’s impedance.
- Metallic shield: Braided copper mesh or aluminum foil that blocks external electromagnetic interference (EMI) and prevents signal leakage outward.
- Outer jacket: A protective PVC or polyethylene coating for physical protection.
The shield is what makes coax special. Unlike twisted-pair Ethernet cable, coax can carry high-frequency RF signals over long distances with minimal loss or interference pickup.
Types of Coaxial Cable
Coax cables are categorized by “RG” (Radio Guide) ratings, a US military standard that stuck around. The number reflects the cable’s physical dimensions and electrical characteristics.
| Type | Impedance | Common Use | Status |
|---|---|---|---|
| RG-6 | 75 Ω | Cable TV, satellite, broadband | Current standard |
| RG-59 | 75 Ω | CCTV, short video runs | Legacy, still used |
| RG-11 | 75 Ω | Long cable runs (50–100m+) | Specialty use |
| RG-58 | 50 Ω | Old 10BASE-2 Ethernet (Thinnet) | Obsolete |
| LMR-400 | 50 Ω | Ham radio, antenna feedlines | Active |
RG-6 — The One in Your Home
If your home has coax, it’s almost certainly RG-6. It supports the higher frequencies needed for digital cable TV, satellite dishes, and DOCSIS cable internet. Its improved shielding (quad-shield versions available) makes it far superior to the older RG-59 for modern applications.
RG-59 — The Old Standard
RG-59 was the go-to cable before RG-6 took over. You’ll still find it in older analog CCTV installations and some legacy wiring. It handles lower frequencies fine but struggles with the bandwidth demands of modern cable systems.
RG-11 — Long Distance
When you need to run coax over 50+ meters without significant signal loss, RG-11 is the answer. It’s thicker and less flexible than RG-6, but it has much lower attenuation per meter. Used by cable companies for trunk lines and in large buildings.
Coaxial Cable Connectors
Unlike Ethernet’s universal RJ-45 click-in connector, coax uses several connector types depending on the application:
- F-connector: The threaded connector on your TV and cable box. Standard for home cable TV and broadband.
- BNC connector: A twist-lock connector common in CCTV systems and professional video equipment.
- PL-259 (UHF): Used in ham radio and antenna systems.
- SMA/SMB: Miniature connectors for RF equipment and wireless devices.
Where Coaxial Cable Is Used Today
Cable Internet (DOCSIS)
Most cable internet providers still use coaxial cable for the “last mile” — the connection from the street junction into your home. The DOCSIS standard (now DOCSIS 3.1) allows speeds up to 10 Gbps over existing coax infrastructure. Your cable modem connects to the wall via an F-connector on RG-6.
Satellite TV and Dishes
The cable running from your satellite dish to your receiver is coax — typically RG-6. Satellite signals operate at higher frequencies than cable TV, so proper shielding and signal quality are critical.
CCTV Security Systems
Analog security cameras use coax (usually RG-59 or RG-6) to transmit video. Modern HD-over-coax formats (HD-TVI, AHD, HD-CVI) can carry 1080p and 4K video over existing coax runs, making it a cost-effective upgrade path for older CCTV systems.
Antenna Systems
For over-the-air TV antennas and ham radio, coax is the standard feedline between antenna and receiver/transmitter. The low signal loss of quality coax is critical when dealing with weak broadcast signals.
Coaxial Cable vs. Twisted-Pair Ethernet
| Feature | Coaxial (RG-6) | Twisted Pair (Cat6) |
|---|---|---|
| EMI resistance | Excellent | Good (UTP) / Better (STP) |
| Max distance | 300–500 meters | 100 meters |
| Flexibility | Moderate | High |
| Max bandwidth | ~10 Gbps (DOCSIS 3.1) | 10 Gbps (Cat6A) |
| Common use | TV, internet, CCTV, RF | LAN, office networking |
| Connectors | F-type, BNC | RJ-45 |
| Installation | Harder (rigid, bulky) | Easy |
For home networking (connecting computers, routers, switches), Ethernet cable is the right choice. Coax is irreplaceable for TV, internet delivery, and antenna systems — but it was never designed for general-purpose data networking between devices.
How to Test a Coaxial Cable
If your TV signal is poor or your cable internet is dropping:
- Check the F-connector is finger-tight — loose connections cause signal loss.
- Inspect the center pin — it should be straight and protruding about 3mm.
- Look for kinks, sharp bends, or crushed sections along the cable run.
- Use a coax cable tester or signal meter to check for continuity and signal level.
- Replace any splitters — each splitter reduces signal strength by ~3.5 dB.
Frequently Asked Questions
Can I use coaxial cable for Ethernet?
Not directly — Ethernet requires RJ-45 connectors and twisted-pair wiring. However, MoCA (Multimedia over Coax Alliance) adapters let you run Ethernet signals over existing coax in your home, which is useful if you can’t run new Ethernet cable.
What’s the maximum length for RG-6 coax?
For cable TV signals, RG-6 is typically reliable up to about 300 feet (90m) without a signal amplifier. For satellite, keep runs under 150 feet where possible. Each splitter or connector adds signal loss.
Is RG-6 or RG-59 better?
RG-6 is better for virtually all modern applications. It has thicker dielectric insulation, better shielding, and handles higher frequencies. Only use RG-59 if you’re maintaining an existing analog CCTV installation that already uses it.
Why does coax still exist when we have fiber?
Infrastructure. Hundreds of millions of homes are already wired with coax. Replacing it all with fiber is expensive and slow. DOCSIS 3.1 lets cable companies offer gigabit speeds over the existing coax network — so there’s no urgency to rip it out.
Related Guides
- Coaxial Cable: What It Is and Why It’s Still Running Through Your Home
- What Is Ethernet? The Guide That Finally Makes It Click
- Copper Wire in Networking: Why Every Ethernet Cable Depends on It
- T568A vs T568B: The Wiring Difference That Actually Matters
- Crossover Cable: Complete Guide
- Copper Wire: Types, Gauges, Uses, and Networking Applications