If you have a cable TV box sitting under your television, there's a thick, often black or white cable running from the wall to that box. That cable is a coaxial cable — often shortened to "coax." It shows up in places you might not expect: behind your router, inside security camera runs, connecting satellite dishes, and even threading through the backbone of data centers that power the internet.

You've probably heard of RG-6 or RG-11 before, maybe even seen those labels printed on the cable jacket at a hardware store. But knowing which one to pick, and why the difference matters, is where a lot of people get stuck.

This guide walks you through what coaxial cable actually is, how it carries a signal without losing it, and how to choose the right type for your project — without drowning you in tables or talking down to you.

A coaxial cable is a type of electrical cable designed to carry radio frequency (RF) signals from one point to another with minimal interference. The "coaxial" part refers to the fact that both the center conductor and the outer shield share the same axis — they're nested inside one another, like pipes inside pipes.

The name sounds technical, but the idea is simple: keep the signal-carrying wire in the middle isolated from external noise and from leaking its own signal outward. That isolation is what makes coax reliable in environments full of motors, WiFi routers, and other electromagnetic chatter.

You'll also see related terms like "coax," "RF cable," or the specific type designations — RG-6, RG-11, RG-59, and the LMR series. RG stands for Radio Guide, a military specification system from the mid-20th century. LMR is a modern commercial equivalent, registered by Times Microwave Systems, designed for lower signal loss in wireless and communications applications.

Think of a coax cable like a walled water pipe. The center conductor is the pipe itself — it's where the signal travels. Around it sits the dielectric insulator, usually made of polyethylene foam or solid plastic, which keeps the center conductor centered and prevents it from touching the outer layers. That physical centering is what gives coax its name and its consistency.

Figure: Coaxial Cable Structure: center conductor, dielectric, shield, and outer jacket

Surrounding the dielectric is a metal shield — either a braided mesh, a foil wrap, or both. This shield acts as a Faraday cage. It blocks external electromagnetic interference (EMI) from corrupting the signal traveling down the center, and it prevents the signal itself from radiating outward and causing interference with nearby equipment.

Finally, the outer jacket is just protection — against physical abrasion, moisture, UV light, and the general abuse of being run through walls, ceilings, or underground conduit.

The whole assembly works because of one key property: impedance, measured in ohms (Ω). Most common applications run either 75 ohms or 50 ohms:

· 75Ω cables (RG-6, RG-11, RG-59) carry video and broadband signals — your cable TV, satellite TV, and broadband internet all run on 75Ω coax.

· 50Ω cables (RG-8, LMR series) carry RF power and data — ham radios, WiFi access points, cell towers, and two-way radio systems prefer 50Ω.

Matching impedance between the cable and the equipment at both ends matters enormously. If you connect a 75Ω cable to a 50Ω antenna, you'll get signal reflections — part of your signal bounces back down the cable instead of reaching the antenna. Those reflections show up as ghosting in video or degraded throughput in data links.

Not all coax is the same. The type you choose affects everything from how far your signal can travel to how hard it is to run through a conduit.

RG-6 Coaxial Cable

This is the workhorse of modern residential and commercial installations. RG-6 coaxial cable has a larger center conductor and better dielectric properties than older types, which means it handles higher frequencies with less signal loss. It's the standard choice for cable television, broadband internet (via DOCSIS technology), and satellite TV installations.
For most home runs — anything under about 150 feet — RG-6 coaxial cable is the right call. It's widely available, inexpensive, and pairs easily with F-type connectors, which screw on by hand and require no special tools.

RG-59 Coaxial Cable 

RG-59 coaxial cable was the standard for decades, especially in closed-circuit television (CCTV) systems. It has a thinner center conductor and higher signal loss at higher frequencies compared to RG-6, which is why it fell out of favor for TV and broadband.
It still makes sense for short analog video runs under 50 feet, particularly in older security camera installations where the cable is already in place and the frequencies involved are lower. If you're pulling new cable, though, RG-6 has largely made RG-59 redundant.

RG-11 Coaxial Cable

RG-11 coaxial cable carries the signal farther with less loss than either RG-6 or RG-59, but it's thicker, stiffer, and harder to work with. The extra stiffness makes it difficult to run through tight bends or residential conduit.

Use RG-11 coaxial cable for long trunk runs — think 150 feet and up — or for situations where signal loss is the primary concern and you have the physical space to accommodate a bulkier cable. It's common in commercial CATV distribution, apartment building installations, and headend environments.

LMR Series (LMR-240, LMR-400, LMR-600)

The LMR series represents a modern evolution in coax design. Where traditional RG cables use plain braided shields, LMR cables use bonded aluminum foil and tight braids that dramatically reduce signal loss — sometimes 30 to 40 percent lower attenuation than an equivalent RG type.

LMR-240 is a common drop-in replacement for RG-8 in 50Ω systems. It's flexible enough to route through buildings and vehicles and is widely used in WiFi installations, DAS (Distributed Antenna System) runs, and cellular signal boosters.

LMR-400 sits in the middle of the LMR range, handling longer runs in commercial and industrial environments where RG-8 would lose too much signal and RG-11 is overkill.

LMR-600 is the low-loss heavyweight for runs over 100 feet in critical RF links — donor antennas for cell signal boosters, ham radio antenna feeders, or point-to-point data links. Reserve LMR for situations where the performance gap justifies the price.

The table below summarizes the four most commonly discussed cable types and where each one makes the most sense.

Loss figures are approximate and vary by manufacturer and specific formulation. Always check the datasheet for the exact cable you're purchasing.

Figure: RG-6 / RG-11 / RG-59 / LMR-240 Cable Comparison

When you're standing in a supply room or scrolling through a catalog, four questions will narrow your choice faster than any specification table.

1. What impedance does your equipment require?

Check the device first. A cable TV box expects 75Ω. A WiFi access point or ham radio wants 50Ω. Never mix the two — the impedance mismatch will degrade your signal.

2. How far does the cable need to run?

Short runs under 150 feet are RG-6 territory. Long runs or trunk lines favor RG-11. If you're working in a 50Ω system and the run is over about 50 feet, consider stepping up from RG-8 to LMR-240 or LMR-400.

3. Is the installation environment electrically noisy?

Factories with heavy machinery, venues with strong RF emissions, and areas near power distribution equipment all generate EMI. In these environments, choose quad-shield cables — the extra foil and braid layers provide better isolation. Single-shield cables are fine for clean residential and office environments.

4. Where is the cable being installed?

Indoor general-purpose installations use CMR (riser-rated) cable. If you're running cable through plenum air-handling spaces, you need CMP (plenum-rated) cable. Outdoor runs call for UV-resistant polyethylene jackets.

Cable television and broadband internet.

The cable that comes into your home from the utility pole is coax, almost certainly RG-11 or RG-6. That signal carries your TV programming and your internet data simultaneously using DOCSIS technology. The latest standard, DOCSIS 4.0, pushes maximum download speeds to 10 Gbps over existing coax infrastructure — a capability that surprised many people who thought fiber had made coax obsolete.

Security and surveillance systems.

Analog CCTV relied heavily on RG-59 and RG-6 runs, and IP-based surveillance cameras often still use coax with video baluns — adapters that let you run IP camera data over coaxial cable using existing infrastructure. Retrofitting old buildings with security cameras is one of the most common reasons to work with RG-59 today.

Satellite television.

The cable running from a satellite dish to the receiver inside the house is specialized RG-6, rated for outdoor UV exposure and weather resistance.

Amateur radio and two-way communications.

Ham radio operators use 50Ω coax — often LMR-400 or RG-8 — to connect transceivers to antennas. The same applies to commercial two-way radio systems, cell signal boosters, and distributed antenna systems inside buildings.

Data center and enterprise networks.

While fiber dominates long campus runs, short-distance high-speed links inside data centers still use coaxial cable in some configurations. The Broadcom PHY ecosystem for 25G and 100G Ethernet over coax is gaining traction as an alternative to twinaxial cables in specific switch-to-server topologies.

These come up often enough that they're worth addressing directly.

1. Mixing 75Ω and 50Ω cable in the same run.

This is the most common and most damaging mistake. Even a short section of the wrong impedance creates an impedance discontinuity — a mismatch point where the signal reflects back. The result is ghosting in video, reduced data throughput, or in high-power RF setups, potential damage to transmitters. If your system is 75Ω, commit to 75Ω from end to end. Same for 50Ω.

2. Choosing copper-clad steel over pure copper in the wrong application.

Copper-clad steel (CCS) center conductors use a thin layer of copper over a steel core. For RF signals at high frequencies, the current travels mainly on the skin of the conductor due to the skin effect, so CCS performs nearly identically to solid copper at those frequencies. But in low-frequency, high-current applications like powering security cameras over coax (PoC — Power over Coax), the current travels through the entire cross-section of the conductor, and steel's higher resistance creates meaningful heat and voltage drop. For those DC power runs, insist on solid copper.

3. Ignoring plenum ratings in commercial buildings.

If you're running cable above a drop ceiling in a commercial space, your local electrical code almost certainly requires plenum-rated cable. Using standard CMR cable in a plenum space is not just a code violation — in the event of a fire, non-plenum cable can release toxic fumes that spread through the HVAC system throughout the building.

Q: How fast can coaxial cable transmit data?

A: Modern DOCSIS 4.0 technology allows coax to carry up to 10 Gbps downstream and 6 Gbps upstream over existing cable infrastructure. In enterprise and data center environments, coax-based Ethernet links support 10 Gbps, 25 Gbps, and even 100 Gbps at short distances. The old figure of 10 Mbps that still appears in some articles refers to very old coax Ethernet standards (10BASE-2) that are no longer relevant.

Q: Can I mix RG-6 and RG-11 in the same installation?

A: You can join them with the right connectors and adapters, but you shouldn't use them interchangeably for long runs. RG-6 and RG-11 have the same 75Ω impedance, so the electrical match is fine — but RG-11's different physical construction and connector styles mean it's best reserved for long trunk runs where its lower loss advantage actually shows up. Mixing them indiscriminately adds connector points, which each introduce a small amount of signal loss.

Q: How far can I run coaxial cable?

A: The practical maximum depends on the frequency and the cable type. A rough guide: RG-6 comfortably handles runs up to about 150 feet for cable TV and broadband. RG-11 extends that to 300 feet or more. For 50Ω LMR cables in RF applications, the maximum is more about your system's link budget and tolerable loss — a 100-foot run of LMR-400 at 2.4 GHz loses about 5 dB, which may or may not fit within your loss budget.

Q: What's the difference between single-shield and quad-shield coax?

A: Single-shield coax has one layer of aluminum braid over a foil wrap. Quad-shield adds a second braid and second foil layer. The extra layers block more electromagnetic interference, which matters in high-EMI environments. For most residential and office installations, single-shield is sufficient. Quad-shield is the right choice when you know you're in a noisy RF environment.

Q: Can I install coax cable outdoors?

A: Yes, but use cable rated for outdoor exposure — look for a polyethylene (PE) jacket rather than PVC. PE jackets resist UV degradation and moisture better. If the cable will be buried directly in the ground, use specifically rated direct-burial coax. For connections to outdoor antennas or satellite dishes, choose cables with weather-resistant connectors or apply self-amalgamating tape at connector joints.

Q: LMR or traditional RG — which should I choose?

A: For most casual or residential projects, RG-6 or RG-8 does the job at a reasonable price. LMR makes sense when your signal loss budget is tight — when you're working with weak signals, long runs, or high frequencies — and when the performance improvement justifies the cost premium. If you're installing a cell signal booster with a donor antenna on the roof, a few extra dollars per foot on LMR-400 instead of RG-8 can mean the difference between a usable signal and a marginal one.