What is a Triaxial Cable?

A triaxial cable is a type of electrical cable which is similar to a coaxial cable but has an extra layer of insulation and a second conducting sheath. Although this type of cable is expensive, it provides greater bandwidth as compared to coaxial cable. A typical triaxial cable has very good interference properties and is less affected by interference than coaxial cables.

Make-Up of Triaxial Cable

There are a number of varieties of electronic applications in which triaxial cables are used. These cables are also used in situations where electromagnetic shielding is desired in order to provide noise free transmission of the signal carried by the central conductor of the cable. But a conventional cable having a center conductor and surrounded by a single flexible coaxial sheath, has inadequate shielding properties and are not able to suppress RFI or EMI interference to the full extent. The first coaxial sheath is a good conductor of electricity and the second coaxial sheath, also a good conductor, is placed in concentric relation to the first one. These two sheaths are connected by an electrical contact or separated by a layer of dielectric materials. The construction that is formed by the layers of dielectric is called triaxial cable. This cable has been made so that it can send all kinds of service signals, as well as video signals. These service signals include the servo-control and remote control signals, audio and interphone. Frequency division multiplexing on the internal coaxial structure is used for this purpose.

Triaxial Cable Usage

The most common use of the triaxial cable is to patch through radio frequency signals at 20 MHz with nominal impedance of 75 ohms. For example, transmission of video signals utilizes triaxial cables. In the case of the coaxial cable, the conductor in the center is surrounded by a dielectric and a conductive braid and a covering jacket. But in the case of a triaxial cable, there is presence of two additional layers which consists of an outer braid that is covered by an outer jacket. An insulation of carefully measured thickness is used to surround the inner conductor. This is done so that the shield braid located in the middle is coaxial there around. There is another insulation layer that surrounds the middle shield and this insulation layer is surrounded by a braided outer shield which is also called the outer jacket. Triaxial electrical connectors are used to terminate triaxial cables. Without any kind of signal degradation, a triaxial cable can be used to transmit data up to a distance of 500 meters (about 540 yards).

Multi-Functionality of Triaxial Cables

Triaxial cables are used in the broadcasting industry to connect the TV to the camera. Multiple functions by using only a single cable can be achieved due to two isolated shields that are used in triaxial cables. This provides more functionality to the camera and power is also ones of its main functions. The two versions of these cables which are used in the television industry are RG11 (1/2 inch) and RG 59 (3/8 inch). In many big events such as concerts and sporting events where professional broadcasts are required, triaxial cables are used.