How does a coaxial copper cable work

Coaxial cable

Coaxial cables or coaxial lines have long been used in network technology for bus or ring cabling. Technically and organizationally, however, structured star cabling based on twisted pair cables has become established. Coaxial cable networks are practically non-existent today.

Structure of a coaxial cable

Inside a coaxial cable there is a single rigid copper wire. This is the inner conductor. There is a braided shield around it as an outer conductor. Isolation separates the two from each other and thus gives the cable additional mechanical stability.
The electric field that builds up when a voltage is applied is only created between the outer and inner conductors. There is no magnetic field outside the cable.

Consideration of the coaxial cable

In principle, coaxial lines represent an asymmetrical form of twisted pair cable. The coaxial cable is therefore an asymmetrical cable. When digital signals are transmitted over a coaxial cable, a potential difference is generated between the inner conductor (core) and the outer conductor (shield) that serves as reference ground. The outer conductor acts as an antenna. Electromagnetic waves emanate from it. In addition, external interference affects the signal flow in the inner conductor.
In order for the electrical field distribution to be effective, the outer conductor (shielding, shielding jacket) must be connected to earth. As a result, both conductors are unequal in terms of voltage with respect to earth. This is why coaxial cables are asymmetrical lines (parallel wire lines are balanced to ground).

Coaxial cable characterizes an impedance of 50 ohms in order to optimize the power transmission in a system. Systems with 75 ohms are used for minimal damping.

Connectors for coaxial cables

The special N connectors are robust and suitable for high performance and up to 18 GHz. SMA connectors are smaller and designed for lower power.
In order to avoid mismatching, connectors must be connected with the correct torque. Manufacturers recommend about 9.5 Nm.
However, cables with BNC connectors are only suitable up to around 500 MHz.

Advantage of coaxial cables over twisted pair cables

  • No interference voltages can get into the cable due to influence.
  • The currents flowing in the cable do not generate any magnetic interference fields.

Applications of coaxial cable

  • Network cable (rare)
  • Antenna cable
  • Transmission of TV and radio (radio / broadcast)

Coaxial cables in network technology

  • 10Base2: Thin Ethernet, ThinWire or Cheapernet
  • 10Base5: Thick Ethernet, Yellow Cable, Thicknet or Thickwire

Overview: lines and cables

Other related topics:

Product recommendations

Everything you need to know about networks.

Network technology primer

The network technology primer is a book about the basics of network technology, transmission technology, TCP / IP, services, applications and network security.

I want that!

Everything you need to know about networks.

Network technology primer

The network technology primer is a book about the basics of network technology, transmission technology, TCP / IP, services, applications and network security.

I want that!