What are LMR 240 Coaxial Cables?

1 Answer
Can you answer this question?

- everything RF

Mar 16, 2023

The LMR 240 Coaxial Cable is a type of cable used for carrying radio frequency (RF) signals with low loss and minimal electromagnetic interference (EMI). It is used in antenna systems and other wireless communication/telecom applications.

LMR 240 Coaxial Cable

LMR 240 Coaxial Cable Construction

The LMR 240 is a 50-ohm, low-loss, flexible, double-shielded coaxial cable with an overall diameter of 0.240 inches, developed by Times Microwave Systems, and has a voltage rating of up to 1500 VDC. It has an internal solid bare copper conductor (carrying the electrical signal), which is enclosed by an insulation layer made of Foam Polyethylene (Foam PE). The insulation layer is then completely enclosed by two shield layers. The first shielding layer is made of aluminum tape, and the outer shield is made of a tinned copper braid. The shields form an outer conductor, which also provides protection from electromagnetic interference (EMI). Finally, the structure is covered with an outermost layer - called a jacket - made of Polyethylene (PE).  The jacket protects the cable core from mechanical, moisture, and chemical issues and environmental conditions.

The LMR 240 cable exhibits capacitance of approximately 24.2 pF/ft (79.4 pF/m) and signal attenuation of around 7.6 dB/100 ft at 900 MHz (signal attenuation of the cable depending on the frequency) and has a velocity of propagation of 83%. It has a center conductor measuring 0.056 inches (1.42 mm) in diameter and an insulation layer measuring 0.150 inches (3.81 mm) in diameter. The double shielding structure of the LMR 240 coax cable offers RF shielding of more than 90 dB.

The high- performance, flexible, low-loss LMR 240 cable can be used virtually anywhere, either indoors or outdoors. The LMR 240 cable is ideal for use in jumper assemblies in wireless communications systems, short antenna feeder runs, and any application (e.g., WLL, GPS, LMR, WLAN, WISP, WiMAX, SCADA, Mobile Antennas) requiring an easily routed, low loss RF cable.

Key Specifications of LMR 240 Coaxial Cables


Typical Value

Overall Diameter (inch)


Characteristic Impedance (Zo)

50 ohms

Maximum Voltage Rating (VDC)


Cable Capacitance (pF/ft)


Inductance (µH/ft)


Attenuation (dB/100 ft, @ 900 MHz)



Foam Polyethylene (Foam PE)

Minimum Bend Radius (inch), installation


Click here to view other RF Coaxial Cables on everything RF.