Technical data

44 Theoretical and general applications www.westermo.com

Coaxial cable

Coaxial cable consists of a single copper conductor surrounded by a screen. In order

to maintain the distance constant the gap is filled with an insulating plastic dielec-

tric layer. The screen is used as protection and for the return signals. Coaxial cable

has good electrical properties and is suitable for communication at high transmis-

sion rates. Initially Ethernet only used coaxial cable and was available in two vari-

ants, the heavier (10Base5) and the lighter (10Base2). Today, Ethernet increasingly

uses a special twisted pair cable (10BaseT). Coaxial cable offers the advantage of

being broadband, i.e. you can send several channels simultaneously (like cable-

TV).

Distance and design

It is not always easy to construct bridges for data communications. Not only must dif-

ferent points be connected by a communications medium, the medium must also be

designed to handle current and future traffic loads. It must also be able to effectively

handle certain transmission speeds, it should not require maintenance and it must be

able to withstand environmental impact.

Since this is a question of determining the right design for the specific conditions of

the particular application, it is impossible to formulate a general design which can be

applied to all areas. The best approach is to discuss different alternatives with one or

several experts in order to arrive at an optimum solution.

Transmission range with different types of cable media and data rates

The diagram below shows the transmission distance that you can attain with different

types of cable media and data rates. The lines with the colours black, blue and green

are a twisted pair cable with the specifications 0.3 mm

and 42 pF/m. As quality and

dimensions differ between different telecom cables, we have used a common cable

used in the Swedish telephone network that has a cross section of 0.2 mm

and atten-

uation of approximately 1.1 dB/km.

Shielding

Dielectric material

Copper conductor

B A C K