Bend Radius is the minimum radius that a Radio Frequency (RF) coaxial cable can be bent to without damage.

To use the calculator, select the type of RF cable type and enter the outer diameter.

The calculated bend radius will have the same dimensions as the diameter.

## Background

Bend radius is a critical specification for RF cables.

RF cables are more sensitive to mechanical stresses than lower frequency cables. It’s not uncommon to bend computer and power supply cables to fit them into small spaces. Doing this with an RF cable can degrade its performance.

Key specifications of RF cables like insertion loss for instance, deteriorate with mechanical stress and damage. In general therefore, it’s advisable to keep RF cables as straight as possible during both storage and operation to preserve their specifications.

Manufacturers specify a minimum bend radius. As the name suggests this is the radius of the smallest circle that can be made by bending the cable.

A lower bend radius results in greater flexibility.

## What happens to a cable when the bend radius limit is exceeded?

When the bend radius is exceeded it alters the characteristic impedance of the cable. It can for instance vary from the standard 50 ohm by quite a bit depending on the extent of the damage.

This results in an increase in discontinuities which results in changes in VSWR and mismatch losses. When the cable is used in a receiver, it results in lower sensitivity. When used in a transmitter it results in lower transmit power.

In general when transmit and receive performance are degraded, the overall range of the communication system is reduced.

Bend Radius = cable diameter x cable multiplier

The cable multiplier depends on the type of cable and specified by the manufacturer.

## Types of Cables Covered by the Calculator

Here is a list of cables included with more added every week:

• LMR 195
• LMR 200
• LMR 240
• LMR 400
• LMR 600
• RG 58
• RG 59
• RG 6
• RG 174
• RG 178