TRANSMISSION MEDIA

UNGUIDED/UNBOUNDED MEDIA
- transport electromagnetic wave without physical conductor
- signal broadcasting through air or water
- types of media : microwave, satellite and wireless

1. TERRESTRIAL MICROWAVE
~ require line-of-sight transmission and reception microwave
~ the taller the antennas, the longer the sight distance
~ signals are propagate in one direction in a time
~ consist of repeater which function to increase the distance
~ two types of antenna :

a) Parabolic Dish
~ catching a wide range of waves and directing to a focus
~ higher frequencies for higher data rates
~ 10-60 GHz

b) Horn
~ looks like a gigantic scoop
~ deflected the waves outward in a series of narrow parallel beams
~ received transmission are collected by the scooped shape

2.  SATELLITE
~ acting as a super tall antenna and repeater
~ relay station : receive on one frequency, amplifies and repeats signal and transmits on another frequency
~ geosynchronous : orbital speed is based on distance from planet
~ 35.784km away from the planet
~ uplink : transmission from earth to the satellite
~ downlink : transmission from satellite to earth

3. WIRELESS @ Wi-Fi
~ transmits computer data over distances using radio waves
~ most commonly used is 802.11 b (11MBps)
~ 802.11 a (54MBps)
~ to communicate over the network, computer must be equipped with a Wi-Fi card
~ types of Wi-Fi card : Wi-Fi PC Cards, USB Adapter, PCI and ISA Adapter etc.