Quick Reference
RG178 Coaxial Cable
50 Ohm • DC – 3 GHz
RG-178 is an extremely thin 50-ohm coaxial cable measuring just 1.75mm in diameter, designed for space-constrained RF assemblies. Its PTFE dielectric and silver-plated conductors deliver reliable performance from DC up to several GHz. Commonly used for internal wiring in test equipment, medical devices, and cellular module pigtails.
RG178 Attenuation
Signal loss in dB per 100 ft at standard RF frequencies.
| Frequency | Loss / 100 ft | Loss / ft | 6 ft | 25 ft |
|---|---|---|---|---|
| 100 MHz | 7.5 dB | 0.075 dB | 0.45 dB | 1.88 dB |
| 450 MHz | 16.5 dB | 0.165 dB | 0.99 dB | 4.13 dB |
| 900 MHz | 24 dB | 0.24 dB | 1.44 dB | 6 dB |
| 1.8 GHz | 35 dB | 0.35 dB | 2.1 dB | 8.75 dB |
| 2.4 GHz | 42 dB | 0.42 dB | 2.52 dB | 10.5 dB |
| 5.8 GHz | 70 dB | 0.7 dB | 4.2 dB | 17.5 dB |
RG178 Power Handling
Approximate maximum continuous power (CW) at 25°C ambient.
| Frequency | Max Power (W) |
|---|---|
| 100 MHz | 30 W |
| 450 MHz | 14 W |
| 900 MHz | 9 W |
| 1.8 GHz | 6 W |
| 2.4 GHz | 5 W |
| 5.8 GHz | 3 W |
Construction & Materials
Center Conductor
Silver-plated copper clad steel, 7×0.1mm
The center conductor carries the RF signal. Material and diameter affect DC resistance, skin effect losses, and overall attenuation.
Dielectric
Solid PTFE
The dielectric insulator separates the center conductor from the shield. PTFE dielectrics offer superior temperature stability and lower loss versus polyethylene.
Shield
Silver-plated copper braid
The outer conductor provides the return path and shields the signal from external interference. More braid coverage means better EMI rejection.
Jacket
FEP
The outer jacket protects the cable from physical damage, UV, chemicals, and moisture. PTFE and FEP jackets handle higher temperatures than PVC.
Velocity Factor
69% (c)
How fast the signal travels relative to the speed of light in vacuum. Higher velocity factor means shorter electrical wavelength per foot — important for phased array and delay-matched applications.
Max Voltage
500 VRMS
The maximum continuous operating voltage. Exceeding this can cause dielectric breakdown. Relevant for high-power transmitters and pulse applications.
Available RG178 Assemblies
Choose a connector combination to see pricing and order. All assemblies are hand-built and ship free within the USA.
SMA MALE to SMA MALE
From $5.99
SMA FEMALE to SMA MALE
From $5.99
RP-SMA MALE to SMA MALE
From $5.99
RP-SMA FEMALE to SMA MALE
From $5.99
N MALE to SMA MALE
From $6.49
N FEMALE to SMA MALE
From $6.49
BNC MALE to SMA MALE
From $6.99
MCX MALE to SMA MALE
From $5.99
RP-TNC MALE to SMA MALE
From $5.99
SMA MALE to TNC MALE
From $5.99
F MALE to SMA MALE
From $6.99
F FEMALE to SMA MALE
From $6.99
FME MALE to SMA MALE
From $6.99
FME FEMALE to SMA MALE
From $6.99
PL259 UHF Male to SMA MALE
From $7.99
SMA MALE to SO239 UHF Female
From $7.99
BNC FEMALE to SMA MALE
From $6.99
SMA FEMALE to SMA FEMALE
From $5.99
135 more configurations available on the RG178 page.
Frequently Asked Questions
What is the impedance of RG178?
RG178 is a 50 Ohm coaxial cable. All standard RF systems (antennas, transceivers, test equipment) use 50-ohm impedance, so RG178 connects directly without any matching network.
What frequency range does RG178 support?
RG178 is rated DC – 3 GHz. At higher frequencies, the attenuation per foot increases, so actual usable range depends on acceptable signal loss for your application.
How much signal loss does RG178 have?
RG178 has 7.5 dB of attenuation per 100 ft at 100 MHz, rising to 70 dB per 100 ft at 5.8 GHz. Use the attenuation table above to calculate loss for any specific length and frequency.
Are CoaxRF RG178 cable assemblies made in the USA?
Yes. Every RG178 assembly is hand-terminated and continuity tested at our US facility. We build each cable to order — nothing is pre-made or drop-shipped from overseas.
Can I order a custom length of RG178?
Yes. In addition to our standard lengths (1, 6, 25, 50, 100 ft and longer), we accept custom-length orders through the Cable Builder. Custom assemblies ship within 1–2 business days.