Microwave
Microwave : Microwave transmission is line of sight transmission. The transmit station must be in visible contact with the receive station. This sets a limit on the distance between stations depending on the local geography. Typically the line of sight due to the Earth’s curvature is only 50 km to the horizon! Repeater stations must be placed so the data signal can hop, skip and jump across the country.
Microwaves operate at high operating frequencies of 3 to 10 GHz. This allows them to carry large quantities of data due to their large bandwidth.
Advantages :
(a) They require no right of way acquisition between towers.
(b) They can carry high quantities of information due to their high operating frequencies.
(c) Low cost land purchase: each tower occupies only a small area.
(d) High frequency/short wavelength signals require small antennae.
Disadvantages :
(a) Attenuation by solid objects: birds, rain, snow and fog.
(b) Reflected from flat surfaces like water and metal.
(c) Diffracted (split) around solid objects.
(d) Reflected by atmosphere, thus causing beam to be projected away from receiver.
