When you’re sourcing RF cables for your next project, it’s easy to get overwhelmed by the letters and numbers on product labels. As someone who’s worked in the RF cable supply industry for over a decade, I’ve heard hundreds of engineers, technicians, and small business owners ask the same question: what’s the actual difference between RG-58 and RG-59? It’s not just a random set of numbers—each cable is built for specific use cases, and picking the wrong one can turn a seamless installation into a costly headache. Let’s break this down, from construction details to real-world performance, so you can make the right choice for your next job. RF Cable
First, let’s start with the basics: RG cables stand for “Radio Guide,” a military specification developed back in the mid-20th century for military radio and radar systems. Today, the RG label is still widely used to describe coaxial cables, even for commercial applications. RG-58 and RG-59 are two of the most common types, but their core construction sets them apart from the very first layer.
Let’s talk about the conductor first, because that’s where signal loss starts. RG-58 has a solid copper core that’s 0.81 millimeters in diameter—about the size of a small grain of rice. Surrounding that core is a layer of polyethylene dielectric, which insulates the conductor from the outer shield. For RG-58, that dielectric is 3.0 millimeters thick, and the entire cable (including the outer jacket) comes in at roughly 5.0 millimeters in diameter. Now, RG-59’s core is noticeably thicker: 1.0 millimeters solid copper. Its dielectric is also thicker, at 4.8 millimeters, making the entire cable around 6.1 millimeters in diameter. That extra copper and dielectric isn’t just for show—it directly impacts signal behavior.
Next, the shield layer, which is critical for blocking interference. RG-58 typically has a 95% braided copper shield. That means 95% of the cable’s circumference is covered by tightly woven copper strands, leaving just 5% open. The purpose of the shield is to keep external radio frequency signals (like Wi-Fi, cell phone signals, or nearby power lines) from bleeding into your cable, and to prevent your cable’s signal from leaking out. For most low-frequency applications (like CB radios, amateur radio, or short-range Wi-Fi), a 95% braid is more than enough. But RG-59 ups the ante here: it has a much thicker shield, usually a double-layered combination of aluminum foil and 95% braided copper. That’s a huge difference for higher-frequency signals. If you’re working with frequencies above 1 gigahertz (GHz), that extra shield is non-negotiable for maintaining signal integrity.
Now, let’s get into the performance metrics that matter most to anyone installing these cables: impedance, signal loss, and frequency range. Impedance is the measure of resistance that the cable presents to the RF signal, and it has to match the devices you’re connecting—otherwise, you’ll get signal reflections, which cause dropouts, slow speeds, or even damage to equipment. This is where a lot of people mix up RG cables: RG-58 is a 50-ohm cable, while RG-59 is 75-ohm. That’s a make-or-break difference. If you plug a 50-ohm device into a 75-ohm cable (or vice versa), you’ll see a significant hit to performance. For example, amateur radio equipment, CB radios, and most two-way radios run on 50-ohm systems, so RG-58 is the go-to here. RG-59, on the other hand, is designed for 75-ohm applications like cable TV, satellite internet, and some CCTV systems.
Signal loss, also called attenuation, is another key factor. Attenuation is the amount of signal that gets weaker as it travels through the cable, and it’s measured in decibels (dB) per 100 feet. The lower the dB number, the less signal you lose. At lower frequencies, like 100 MHz, RG-58 has an attenuation of about 5.2 dB per 100 feet, while RG-59 is around 4.0 dB per 100 feet. That might not sound like a big difference, but at higher frequencies, that gap widens a lot. At 1 GHz, RG-58 loses roughly 21.5 dB per 100 feet, which means you lose almost half your signal over a 50-foot run. RG-59 at 1 GHz only loses about 12.5 dB per 100 feet—nearly half the loss. For long runs or high-frequency applications, that’s a massive difference. Imagine running a 100-foot cable for a satellite dish: using RG-58 would leave your signal so weak that your dish would barely lock on, while RG-59 would keep it strong and stable.
Frequency range is directly tied to signal loss, and that’s another area where the two cables differ. RG-58 is rated for a maximum frequency of around 1 GHz, which is fine for its intended uses: CB radios (27 MHz), amateur radio bands (like 144 MHz and 430 MHz), and standard 2.4 GHz Wi-Fi. But if you’re working with 5 GHz Wi-Fi, satellite signals (which often run at 1.2 GHz or higher), or HD cable TV (which uses frequencies up to 3 GHz), RG-58 starts to fall apart. It can’t handle those higher frequencies without excessive signal loss and interference. RG-59, with its thicker conductor and better shield, is rated for up to 3 GHz, making it suitable for those higher-frequency commercial applications.
I’ve seen firsthand what happens when people mix these cables up. A few years back, a local restaurant came to me because their new CCTV system was having constant dropouts. They’d installed what they thought was the right cable: they bought a spool of “RG-59” from a big-box store, but it was actually a cheaper, lower-quality version that was only 50-ohm. When their technician plugged in their 75-ohm cameras, the signal was bouncing all over the place. We swapped it for premium RG-59, and the dropouts stopped entirely. Another common mistake: amateur radio hams using RG-59 for their base station antenna. The 75-ohm impedance mismatch would cause their signal to reflect back into their transmitter, reducing their range and even putting unnecessary strain on the radio. I’ve had to repair a few transmitters because of that exact mistake.
Now, it’s worth noting that not all RG-58 and RG-59 cables are created equal. The old military specifications are the baseline, but today, many manufacturers make variations for commercial use. For example, there’s RG-58A/U, which has a solid copper core instead of the cheaper copper-clad steel core found in some budget RG-58 cables. That solid copper core has less resistance, so less signal loss. For RG-59, there’s often a difference between standard 95% braid and double-shielded versions, which are better for noisy environments like office buildings with lots of other electronics. As a supplier, I always tell customers to prioritize the core material first: solid copper is always better than copper-clad steel for low-loss, reliable performance, even if it costs a bit more upfront.
Let’s wrap this up with a clear breakdown of when to use each cable, so you don’t have to guess. Use RG-58 if you’re working with: amateur radio, CB radios, two-way business radios, 2.4 GHz Wi-Fi, short-range test equipment, or any 50-ohm device for low to medium frequencies. Its 50-ohm impedance, smaller size, and lower cost make it ideal for these applications. Use RG-59 if you’re working with: cable TV, satellite systems, CCTV security cameras, 5 GHz Wi-Fi, long-distance signal runs, or any 75-ohm device. The thicker conductor, better shielding, and lower signal loss at high frequencies make it the better choice here.
If you’re still not sure which cable is right for your project, or you want to compare premium vs. budget options, don’t hesitate to reach out. We’ve been supplying RF cables to small businesses, tech companies, and independent installers for years, and we can help you pick the exact cable that fits your budget and performance needs. Skip the trial-and-error—let’s make sure your next installation goes smoothly.
SCSI Connector References
- Terman, F. E. (1943). Radio Engineers’ Handbook. McGraw-Hill.
- RG Cable Specifications: Military and Commercial Coaxial Cable Standards. National Association of Broadcasters.
- Attenuation Characteristics of Coaxial Cables Across RF Frequencies. IEEE Transactions on Microwave Theory and Techniques, 1952.
- Coaxial Cable Impedance Matching for Commercial RF Systems. RF Design Magazine, 2001.
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