What are RG120 Coaxial Cables?

1 Answer
Can you answer this question?

- everything RF

Jan 18, 2023

RG120 Coaxial Cables are a type of cable commonly used for carrying high-frequency electromagnetic signals for telecommunications and networking. They are designed to transmit radio frequency (RF) signals over longer distances while ensuring minimal signal attenuation. These cables are therefore suitable for long-haul communication links and other wireless infrastructure applications where low loss and high performance is required.


The RG120/U is a 50-ohm coaxial cable with an overall diameter of 0.523 inches and a voltage rating of up to 6000 Vrms. It has an internal bare copper conductor (carrying the electrical signal), which is enclosed by an insulation layer made of Polytetrafluoroethylene (PTFE). The insulation layer is then completely enclosed by 2 bare copper braid shields that form the outer conductor and also provide shielding against electromagnetic interference (EMI). The shield layer is then covered by a layer- called a jacket - made of FG-V. The jacket protects the cable core from mechanical, moisture, and chemical issues. Finally, the structure is covered with an outermost layer-called armor. The armor is made of an aluminum braid and offers extra mechanical protection to the cable. 

The RG120/U cable exhibits capacitance of approximately 30 pF/ft (98.68 pF/m), and signal attenuation of around 3.8 dB/100 ft at 400 MHz (signal attenuation of the cable depends on the frequency). It has a center conductor measuring 0.1020 inches (2.59 mm) in diameter and an insulation layer measuring 0.332 inches (8.43 mm) in diameter.

Key Specifications of RG-120/U Coaxial Cables


Typical Value

Overall Diameter (inch)


Characteristic Impedance (Zo)

50 ohms

Maximum Voltage Rating (RMS)

6000 V

Cable Capacitance (pF/ft)


Attenuation (dB/100 ft, @ 400 MHz)



Polytetrafluoroethylene (PTFE)

Click here to view a list of coaxial cables on everything RF.