Are All Coaxial Cables the Same? What to Know Before Buying

A coax cable looks like a simple tube of wire, but inside it is a precision part: a center conductor, an insulating dielectric, a metallic shield, and an outer jacket. Get the impedance wrong and a clean signal turns into dropouts, pixelated channels, or a modem that keeps renegotiating. The four specs below decide whether a cable helps or hurts.

Does The Ohm Rating Actually Matter?

Impedance is the first thing to match, because it is not a preference — it is a system requirement. Home TV, satellite, cable internet, and CCTV run on 75-ohm coax, while radio communications and RF test gear typically use 50-ohm coax.

Mixing the two families costs you signal. Feed a 75-ohm TV system with 50-ohm cable and you introduce reflections and extra loss instead of a clean match. RG59, RG6, and RG11 all share a nominal 75-ohm impedance, so they belong to the same family, but they are not interchangeable with 50-ohm cable by any stretch.

Which Coax Should You Buy?

RG6 is the modern default for cable TV, satellite, and cable-modem drops, and for most US homes it is the right answer. RG59 is a thinner, higher-loss cable best kept to short legacy video runs. RG11 carries the same 75-ohm signal with the lowest loss of the three, which matters over long distances.

What Separates One Coax From Another?

Beyond impedance, four variables decide performance: loss per foot, shielding, conductor construction, and physical size.

• Signal loss: every cable loses some signal, and loss climbs with frequency and distance. Longer runs and higher frequencies push you toward lower-loss cable like RG11.
• Shielding: more shield layers mean better rejection of outside interference. Quad-shield RG6 is a common pick for satellite and noisy environments.
• Conductor and construction: two cables both stamped “RG6” can perform differently based on shield count, conductor material, and build quality.
• Size and flexibility: thicker cables like RG11 resist bending and need compatible connectors and fittings, which affects how you route them.
• Connector compatibility: verify the cable’s connector matches your device before buying, since an adapter adds its own loss.

Common Mistakes That Cost Signal Quality

Most bad coax buys trace back to the same shortcuts, and each one is easy to avoid once you know the pattern.

Buying on the “RG” label alone is the biggest trap. The label tells you the family, not the impedance, shielding, or loss, so two RG6 cables can behave very differently. The second mistake is using 50-ohm cable in a 75-ohm TV or broadband system, or the reverse, because the mismatch causes loss and poor performance rather than a clean connection. A third is grabbing RG59 for a long TV or broadband run, where its higher loss can visibly degrade picture and signal. Overlooking that thick RG11 needs compatible connectors and won’t bend around tight corners rounds out the list.

The jacket marking and the spec sheet matter more than the marketing copy on the package. If you want a shortcut, our tested picks for the best coaxial cable for cable TV narrow the field by impedance and shielding. The Federal Communications Commission’s own consumer guidance on coaxial cable construction and impedance confirms the 75-ohm/50-ohm split that drives every buying decision here.