Published on 10/13/2026 • Updated on 10/13/2026
RG58 is a nominal 50 Ω coaxial cable family widely used for short radio, instrument and antenna interconnects. Common constructions have a polyethylene dielectric, PVC jacket and an outside diameter near 4.9 mm. The name alone does not identify conductor construction, attenuation, shielding or a guaranteed frequency range.
A 2 m radio jumper and a 20 m antenna feeder can use the same RG58 reel and deliver very different results. At 1 GHz, a representative stranded RG58 construction loses about 0.748 dB/m. That is roughly 1.50 dB over 2 m, but nearly 15 dB over 20 m before connectors. Length is not a housekeeping detail.
This guide explains RG58 specifications through the practical decision: which construction, how much loss, what connector and where the cable stops being the sensible choice. All numerical ratings are reference-part values or labeled design assumptions, not promises for every RG58 cable assembly.
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Start with the cable part number, not a universal RG58 table. Two products carrying the family name can differ in conductor material, braid coverage and impedance. The reference below compares published constructions 8259 and 9201 without implying that SigmaRF supplies either part by default.
| Specification | Stranded reference 8259 | Solid reference 9201 |
|---|---|---|
| Center conductor | 20 AWG, 19-strand tinned copper | 20 AWG solid bare copper |
| Dielectric / jacket | PE / PVC | PE / PVC |
| Shield | 95% tinned copper braid | 80% bare copper braid |
| Nominal diameter | 4.90 mm | 4.90 mm |
| Nominal impedance | 50 Ω | 52 Ω in electrical table |
| Velocity factor | 66% | 66% |
| Capacitance | 101 pF/m | 93.5 pF/m |
| Operating temperature | -30 °C to +75 °C | -30 °C to +80 °C |
The solid reference is marketed as 50 Ω RG58, but its electrical table lists 52 Ω. That detail is worth noticing, not silently changing. The same datasheet has an RG-8 label in its descriptive text while its heading and construction identify RG58. For a controlled build, resolve contradictory supplier documentation before approving the part.
Key idea: RG58 is a cable family, not a complete purchase specification. If the impedance, braid or conductor matters, name the approved part and acceptance limits on the drawing.
RG58 attenuation is frequency-dependent cable loss, usually expressed in dB per length. Convert units before comparing and distinguish nominal cable values from a maximum assembly insertion-loss limit. This chart uses the two reference constructions at their stated nominal values; the conversion divisor is 30.48 m per 100 ft.
| Frequency | 8259 (dB/100 ft) | 8259 (dB/m) | 9201 (dB/m) |
|---|---|---|---|
| 10 MHz | 1.5 | 0.049 | 0.036 |
| 50 MHz | 3.7 | 0.121 | 0.082 |
| 100 MHz | 5.4 | 0.177 | 0.125 |
| 200 MHz | 8.1 | 0.266 | 0.184 |
| 400 MHz | 12.4 | 0.407 | 0.276 |
| 700 MHz | 17.7 | 0.581 | 0.384 |
| 900 MHz | 21.1 | 0.692 | 0.449 |
| 1000 MHz | 22.8 | 0.748 | 0.476 |
At 100 MHz, the stranded reference loses about 0.177 dB/m; at 1 GHz it loses about 0.748 dB/m. At 400 MHz, 5 m contributes about 2.034 dB of nominal cable loss. Keep units visible in the spreadsheet. A value of 12.4 dB/100 ft is not 12.4 dB/m.
The solid reference has lower published nominal attenuation at these points, but it also has a different shield and nominal impedance. Do not select only the lowest loss row. Construction, required shielding, handling and connector compatibility can matter more than a small loss difference over a short jumper.
For a long or high-frequency feeder, compare a larger low-loss cable using the same frequency and length. RG58 is not assigned a universal hard cutoff at 1 GHz by this chart; rather, these particular data end at 1 GHz. Above the documented band, obtain suitable cable and finished-assembly data instead of extrapolating a guarantee.
RG58 is most useful where a moderate-diameter flexible 50 Ω interconnect has a manageable loss budget: short HF/VHF/UHF equipment jumpers, radio-to-instrument links and compact antenna connections. It is less attractive as the frequency or feeder length grows.
Radio jumpersRF instrumentsShort antenna leadsHF/VHF interconnects
A sensible RG58 selection
For a tight, high-temperature internal jumper, RG316 may be more suitable than a PE/PVC RG58 reference. For a fixed precision microwave route, investigate another flexible cable or a semi-rigid assembly. Read SigmaRF's cable selection guide and the RG316 guide for those separate decisions rather than treating RG58 as the default for every RF connection.
Choose RG58
Short 50 Ω equipment links where the selected cable fits the loss, routing and environmental limits.
Choose something else
Long high-frequency feeders, high-temperature routes beyond the jacket rating or precision phase-sensitive work.
Specify the complete assembly, not just RG58
Send the frequency band, connector interfaces, finished length and routing drawing. SigmaRF can match the cable and terminations to your application.
The whole assembly is limited by the least suitable cable, connector or strain-relief component. A cable voltage line is not an RF power rating, and an operating temperature is not permission to solder or install without process controls.
| Item | Reference data | What it does not prove |
|---|---|---|
| Installation bend radius | 48 mm for 8259; 49 mm for 9201 | Continuous-flex life or permission to kink the connector exit |
| Cable voltage | 1900 V for 8259; 1900 V RMS for 9201 | An assembly RF power rating or connector withstand rating |
| Fire / installation use | Both indicate indoor, not riser or plenum in suitability text | Approval for every building cable route |
| Frequency chart | Nominal attenuation points through 1000 MHz | Universal maximum frequency of RG58 |
⚠️ Do not turn a cable-only voltage into transmitter power. Frequency, duty cycle, ambient heat, altitude, VSWR and connectors require a separate power and derating check.
For outdoor service, specify the exact jacket suitability and weather sealing at the interfaces. The reference 8259 describes black aerial use with messenger support, not a blanket direct-burial permission. Mechanical strain should be carried by the installation support, not by a cable connector attached to a radio.
Step 01
Define interfaces and electrical limits
Specify connector family, male/female interface, angle, polarity and impedance. Compatible RG58 variants of BNC, TNC, N and SMA can be considered, but each connector must accept the selected cable dimensions and preparation.
Step 02
Define length and route
Give finished length in mm or m, measurement datums, tolerance, bend plan and any right-angle connector clocking. Protect the cable against pinch points and provide strain relief without a sharp bend behind the ferrule.
Step 03
Define the acceptance sweep
Specify operating band, maximum VSWR and insertion loss, reference planes and report needs. Continuity and insulation tests check different failure modes; a DC pass does not establish RF performance.
SigmaRF VNA-sweeps every assembly for VSWR and insertion loss before shipment. Its overall 100 MHz to 40 GHz capability includes different cable and connector systems; it is not an RG58 rating. SigmaRF supports volume builds in Vadodara, India, and precision work in the Cleveland area, USA. Lead times can be as short as 2 days for suitable parts and builds, subject to the agreed order.
Keep the approved cable and connector part numbers with the drawing for repeat procurement. SigmaRF's RF cable assembly design guide covers PCB-to-antenna reliability, while its VNA loss-measurement guide explains reference-plane and fixture choices. This RG58 guide supplies the cable-specific decision, not a substitute for those test procedures.
Assume a 2 m 400 MHz jumper using the stranded reference cable. Use its nominal 12.4 dB/100 ft attenuation and a hypothetical 0.05 dB allowance per connector. The assumed assembly budget is 1.00 dB. Connector allowances are illustrative, not SigmaRF test results.
Cable attenuation = 12.4 / 30.48 = 0.407 dB/m
Cable loss = 0.407 x 2.0 = 0.814 dB
Estimated loss = 0.814 + 0.05 + 0.05 = 0.914 dB
Nominal margin = 1.000 - 0.914 = 0.086 dB
Matched power ratio = 10^(-0.914/10) = 0.810, about 81.0%
A nominal margin of only 0.086 dB is narrow. Cable variation, connector behavior, temperature and measurement uncertainty may consume it. Shorten the jumper, use a lower-loss construction or revise the approved budget with measured evidence. Do not release production on this arithmetic alone.
At a nominal 66% velocity factor, delay is about 5.05 ns/m, so 2 m contributes about 10.1 ns. Physical length alone does not guarantee electrical phase matching. If timing or phase is important, specify an electrical-length tolerance and measure the completed assembly.
Avoid these RG58 shortcuts
What are RG58 cable specifications?
Typical RG58 is nominal 50 Ω coax near 4.9 mm diameter, often using PE insulation and a PVC jacket. Conductor, braid, loss and environmental ratings vary by part. Specify an approved construction rather than relying on the family name.
How much loss does RG58 have at 100 MHz?
The stranded reference used here has 5.4 dB/100 ft, about 0.177 dB/m, at 100 MHz. The solid reference has 3.8 dB/100 ft. These are nominal values for different parts, not universal maximum ratings.
Is RG58 suitable for 1 GHz?
Check the exact cable and finished assembly. At 1 GHz the stranded reference loses about 0.748 dB/m, which may fit a short jumper but becomes expensive in link budget over a long feeder.
What is RG58 used for?
Short radio jumpers, RF instrument links and antenna interconnects are common uses where impedance, environment and loss fit. A longer or higher-frequency feeder often benefits from a larger lower-loss cable.
Can RG58 use SMA, BNC or N connectors?
Yes, when the exact connector variant accepts the selected cable. Confirm impedance, conductor preparation, ferrule dimensions and termination instructions. A family name alone does not guarantee mechanical fit.
Can SigmaRF make custom RG58 assemblies?
SigmaRF can build standard and custom coaxial assemblies to an agreed drawing. Provide cable and connector parts, finished length, operating band, environment and RF test limits. Confirm lead time for the selected build.
RG58 is a practical interconnect when the selected construction and length meet the RF budget. Its usefulness comes from a suitable complete assembly, not a generic "low-loss" label. The attenuation chart should drive the route length before procurement.
Name the cable part, compatible interfaces, routing constraints and pass/fail band. For long feeders, compare alternatives at the actual frequency. For short radio jumpers, controlled terminations and agreed tests often matter more than a broad family comparison.
Build your RG58 assembly around the real requirements
Send the frequency band, connector interfaces, finished length and routing drawing. SigmaRF can match the cable and terminations to your application.