Copper
Twin wire Coaxial cable (telephone lines)
most home telephone lines are twin wire cables that run from the house to the nearest telephone box. These wiress
Ethernet Cables
Fibre Optic
Radio Waves
Radio Waves
Lower Frequency Waves (3KHz to 300MHz)
Radio waves can travel as ground waves and also bounce off the upper atmosphere, allowing their transmission beyond visible sight(40 miles+ )
Radio waves are used to transmit radio and television signals.
Microwaves
Microwaves
High frequency waves 300Mhz to 300GHz
Microwaves are Line of Sight and therefore are limited to 40-50 mile transmission distances, due to the curvature of the earth.
WIFI and Bluetooth use microwave signals in the lower end of the spectrum (2.4Ghz). This end of the spectrum has a low enough frequency to allow some penetration through walls and therefore allows it to be used in wireless LANs.
Satellite Technology
Satellite Tecnology
As Microwaves are limited in their transmission distance by line of sight, the signals need to be relay using satellites if they are to be transmitted globally.