Published on 10/13/2026
RG174 is a miniature nominal 50 Ω coaxial cable used where a short RF connection needs a small diameter and manageable flexibility. A common construction uses PE insulation and a PVC jacket around a stranded copper-clad steel conductor; exact loss, temperature and shielding depend on the cable part.
A short antenna lead can benefit from thin coaxial cable, but a long feeder can lose the advantage before the antenna sees the signal. The useful question is not whether RG174 is small enough. It is whether the complete assembly meets the loss budget and survives its route.
This guide uses reference cable 8216 for numerical RG174 specs and comparisons, with illustrative calculations clearly separated from product ratings. SigmaRF can build the selected interfaces and length to an agreed drawing, but a family name alone is not an acceptance test.
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The reference RG174 construction is 2.79 mm in overall diameter, with 26 AWG stranded bare copper-clad steel, solid PE dielectric, 90% tinned-copper braid and PVC jacket. It is not solid-copper miniature coax, and its braid coverage does not equal a measured shielding effectiveness in dB.
| Property | Reference 8216 value | Selection consequence |
|---|---|---|
| Nominal impedance | 50 Ω | Match 50 Ω equipment and connectors |
| Conductor | 26 AWG, 7 strands, copper-clad steel | Check contact preparation and termination |
| Nominal diameter | 2.79 mm | Confirm connector ferrule and cable group |
| Dielectric / jacket | PE / PVC | Not the PTFE/FEP combination of common RG316 |
| Capacitance / velocity | 101 pF/m / 66% | Use exact part data for delay-sensitive designs |
| Operating temperature | -30 °C to +75 °C | Connector, sleeve and route may narrow this |
| Installation bend radius | 28 mm | Do not bend sharply at the connector exit |
These values describe one published product. An RG174 supplied by another source may use a different diameter or jacket specification. Require an approved cable part and a controlled drawing for repeat orders. Qualification, flame class and outdoor suitability also need part-specific evidence.
Key idea: A small outside diameter helps fit. It does not prove low loss, continuous-flex life, phase stability or environmental qualification.
RG174 signal loss rises with frequency and length. The chart below converts the reference nominal attenuation into dB/m using 100 ft = 30.48 m. It is cable-only attenuation, not maximum insertion loss for a finished assembly.
| Frequency | Nominal dB/100 ft | Nominal dB/m | Loss over 0.30 m, dB |
|---|---|---|---|
| 10 MHz | 3.3 | 0.108 | 0.032 |
| 50 MHz | 5.8 | 0.190 | 0.057 |
| 100 MHz | 8.4 | 0.276 | 0.083 |
| 200 MHz | 12.5 | 0.410 | 0.123 |
| 400 MHz | 19 | 0.623 | 0.187 |
| 700 MHz | 27 | 0.886 | 0.266 |
| 900 MHz | 31 | 1.017 | 0.305 |
| 1000 MHz | 34 | 1.115 | 0.335 |
At 900 MHz, the reference is about 1.017 dB/m. A 300 mm jumper contributes about 0.305 dB, while a 3 m route contributes about 3.051 dB before connectors. A thin lead that works inside an enclosure can be the wrong cable between that enclosure and a remote antenna.
Do not extend the 1 GHz table into a universal maximum-frequency claim. Obtain documented cable and assembly performance for the required band. For wider-band or higher-frequency work, select a cable and connector system whose specified limits cover the job. SigmaRF's signal-loss and VNA measurement guides explain the broader loss and calibration issues.
Thin coax is a good choice when space is scarce and the RF run is short enough to tolerate its loss. Common considerations include panel-to-module leads, compact receiver interconnects and low-power antenna jumpers. Choose based on actual electrical and mechanical requirements rather than the smallest available cable.
Compact antenna leadsEnclosure interconnectsReceiver jumpersShort RF fixtures
Choose RG174
A short 50 Ω link needs compact routing and its selected PE/PVC construction fits the environment and loss limit.
Choose another construction
The job needs a long feeder, high-temperature materials, repeated dynamic flexing or verified phase stability after motion.
A stranded conductor does not make the cable suitable for continuous bending. The bend radius in a datasheet is a geometry limit, not a flex-cycle count. If the equipment moves during use, specify the motion profile and qualification test instead of hoping a flexible-looking cable will survive.
Specify the complete RF assembly
Send the frequency band, connector interfaces, finished length and routing drawing. SigmaRF can match the cable and terminations to your application.
RG174 and RG316 can both suit miniature 50 Ω links, but their common materials differ. The following comparison uses reference 8216 and 83284, not every variant available in either family.
| Parameter | RG174 reference | RG316 reference |
|---|---|---|
| Diameter | 2.79 mm | 2.5 mm |
| Dielectric / jacket | PE / PVC | PTFE / FEP |
| Temperature | -30 °C to +75 °C | -70 °C to +200 °C |
| Loss at 100 MHz | 0.276 dB/m | 0.272 dB/m |
| Loss at 1 GHz | 1.115 dB/m | 0.951 dB/m |
| Conductor | Bare copper-clad steel | Silver-plated copper-clad steel |
At 100 MHz the reference loss figures are almost identical. At 1 GHz the difference over 300 mm is about 0.049 dB. For a short jumper, the material and temperature choice can matter more than that small loss delta. Neither row establishes the complete assembly temperature or a guaranteed connector loss.
Key idea: RG174 is not inherently better because it is called thin coax, and RG316 is not automatically a low-loss feeder. Compare the selected parts at the actual frequency and length.
Step 01
Define cable and interfaces
Specify the cable part, connector A and B, polarity, impedance and body angle. Check the approved cable group: similarly sized RG174 and RG316 are not automatically interchangeable in a connector.
Step 02
Define mechanical length and routing
Use finished length in mm, measurement datums and tolerance. Add strain relief, connector clocking and bend limits. Avoid side-loading small snap-on connectors or making the coax carry enclosure forces.
Step 03
Define RF and inspection limits
Specify VSWR and insertion-loss limits through the operating band, plus continuity and short checks. State test reference planes and fixture handling. A DC pass does not establish RF performance.
SigmaRF VNA-sweeps every assembly for VSWR and insertion loss before shipment. Its overall RF assembly capability spans 100 MHz to 40 GHz across suitable cable and connector systems, not every product discussed here. Volume work is supported in Vadodara, India, with precision work in the Cleveland area, USA. Lead times can be as short as 2 days for suitable builds, subject to parts, quantity and the agreed specification.
For repeat procurement, preserve the cable and connector parts, strip/crimp instructions and approval record. See SigmaRF's cable selection guide and PCB-to-antenna assembly design guide for the broader interconnect decisions. This article focuses on RG174-specific length and material trade-offs.
Assume a 300 mm receiver lead at 900 MHz using reference nominal attenuation of 31 dB/100 ft. Allow a hypothetical 0.05 dB for each connector, with a hypothetical assembly budget of 0.60 dB. These allowances are not measured SigmaRF values.
Attenuation = 31 / 30.48 = 1.017 dB/m
Cable contribution = 1.017 x 0.300 = 0.305 dB
Estimated matched-path loss = 0.305 + 0.05 + 0.05 = 0.405 dB
Nominal margin = 0.600 - 0.405 = 0.195 dB
Matched power ratio = 10^(-0.405/10) = 0.911, about 91.1%
The arithmetic provides a starting point. It does not include a guaranteed manufacturing margin, thermal change or calibration uncertainty. Verify the completed assembly against the agreed limit. Doubling the cable length approximately doubles cable attenuation in dB at the same frequency, but connector contributions remain separate.
Avoid thin-coax shortcuts
Before releasing the RFQ
What are RG174 cable specs?
One common RG174 construction is 50 Ω, 2.79 mm diameter, with 26 AWG stranded copper-clad steel, PE insulation and PVC jacket. Exact loss, shielding and environmental limits are part-specific.
How much RG174 signal loss occurs at 900 MHz?
Reference 8216 specifies 31 dB/100 ft, about 1.017 dB/m, nominal cable attenuation. A 300 mm length contributes about 0.305 dB before connector effects.
Is RG174 good for antenna pigtails?
It can fit short 50 Ω antenna links where the loss and environment are acceptable. Specify cable and connector variants, length, routing and test band. Longer feeders often need a lower-loss alternative.
Is RG174 thinner than RG316?
Not necessarily. The reference RG174 here is 2.79 mm and the reference RG316 is 2.5 mm. Family names and marketing labels do not replace exact diameter and cable-group data.
Can RG174 be used for continuous flexing?
Do not infer flex-cycle life from its flexibility or bend radius. A moving application needs a motion profile, suitable construction and qualification test.
Can SigmaRF supply custom RG174 assemblies?
SigmaRF supports standard and custom coaxial assemblies. Provide exact interfaces, approved cable, finished length, environment and RF limits so the build and test method can be agreed.
RG174 is useful when the route is short and the space is tight. Its small size is an advantage only after loss, environment and connector compatibility are checked. The wrong thin cable is still the wrong cable.
Use the exact part datasheet and calculate loss at the highest operating frequency. Then specify the finished assembly and verify it. That approach makes compact RF connections repeatable instead of relying on the family name.
Build an RF 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.