What are RG401 Coaxial Cables?

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- everything RF

Feb 1, 2023

RG401 Coaxial Cables are a type of cable used for carrying radio frequency signals over longer distances, thereby making them suitable for telecommunications infrastructure, networking, and wireless applications.


RG401/U Cable Construction

The RG401/U is a 50-ohm coaxial cable with an overall diameter of 0.250 inches and a voltage rating of up to 3000 Vrms. It has an internal silver-covered 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 a bare copper tube (BC Tube) shield that forms the outer conductor and also provides shielding against electromagnetic interference (EMI). 

The RG401/U cable exhibits capacitance of approximately 29.4 pF/ft (96.5 pF/m), signal attenuation of around 4.6 dB/100 ft at 400 MHz (signal attenuation of the cable depending on the frequency), and has a velocity of propagation of 69.5%. It has a center conductor measuring 0.0645 inches (1.63 mm) in diameter and an insulation layer measuring 0.215 inches (5.46 mm) in diameter. This cable is ideal for high-frequency signal transmission of wireless communications, radar, and microwaves. It has an operating temperature of -55˚C to + 90˚C.

Key Specifications of RG401/U Coaxial Cables


Typical Value

Overall Diameter (inch)


Characteristic Impedance (Zo)

50 ohms

Maximum Voltage Rating (Vrms)

3000 V

Cable Capacitance (pF/ft)


Attenuation (dB/100 ft, @ 400 MHz)



Polytetrafluoroethylene (PTFE)

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