Flexible Microwave Cable

This is a post about one of our Wavetronix products.

There are essentially two different categories of RF/microwave cable. One is semi-rigid coaxial cable and the other is flexible coaxial cable. Coaxial cable has an inner conductor that is surrounded by an outer shield that acts as an insulating layer. Both of these types of cables are used in RF/microwave systems with an impedance of 50 ohms, but they can also be used in broadcast applications with an impedance of 75 ohms.

Obviously, both of these cable operate in the RF to microwave frequency range. The semi-rigid coaxial cable can only be bent one time at least without a significant loss it its usefulness. This is a limiting factor for it's use. The flexible coaxial cable, on the other hand, can be bent more easily than the semi-rigid coaxial cable, and more often, without significantly derating it.

The use of flexible coaxial cable has been on the increase over the last several years, whereas the semi-rigid coaxial cable has, for the most part, been on the decline. The semi-rigid cable still has its uses, such as in satellites and space applications, but the number of these viable applications has been dwindling in recent years.

The flexible cable has replaced many of the semi-rigid coaxial cable applications because of its ease in forming it to a specific shape. Even so, the semi-rigid cable provides superior shielding because it has a solid copper outer sheath whereas the flexible cable has a braided outer conductor.

In both cables signal leakage can create a problem. It can occur from the outside environment inside the cable resulting in noise and signal disruption. This signal leakage can also occur within the cable itself causing RF interference of nearby devices.

Both flexible coaxial cable and semi-rigid coaxial cable have their advantages and disadvantages. Choosing the correct one will depend upon the specific application, but these days the chances are it will be the flexible cable.