|
Band
|
Range
|
Uses
|
|
Very Low Frequency(VLF)
|
3KHz-30KHz
|
Long range Radio Navigation
|
|
Low Frequency(LF)
|
30KHz-300KHz
|
Radio
Beacons
|
|
Medium Frequency(MF)
|
300KHz-3MHz
|
AM Radio
|
|
High
Frequency(HF)
|
3MHz-30MHz
|
Citizen
Band(CB)/Ship/Aircraft Communication
|
|
Very High Frequency(VHF)
|
30MHz-300MHz
|
VHF TV, FM Radio
|
|
Ultra High Frequency(UHF)
|
300MHz-3GHz
|
UHF TV,
Cellular phones
|
|
Extremely High Frequency(EHF)
|
3GHz-30GHz
|
Satellite communication
|
|
Superior High Frequency(SHF)
|
30-GHz-300GHz
|
Radar,
Satellite
|
Thursday, November 30, 2017
Frequency Spectrum
Wireless Media
It is also known as a wireless media.
Wireless media transmit and receive electromagnetic signals without and
electrical or optical conductor. Here
transmission and reception achieved by means of an antenna. For transmission
antenna emits signal into medium and for reception antenna picks up electromagnetic
signals from the surrounding medium. The two forms of transmission:
Directional: - In this, transmitting
antenna puts out a focused electromagnetic beam. The transmitting receiving
antenna must be aligned, known as Point-to-Point Communication.
Omni-directional:
- In this the transmitted signal spreads out in all direction and be
received by many antenna inspite of direction.
According to frequency range the wireless media is
divided into three parts:-
·
Radiowave
(30MHz-1GHz): Omni directional transmission
·
Microwave
(1-40GHz): Point-to-Point Communication
·
Infrared (100GHz-1000
THz light frequencies): Local Point to Point,
Multipoint application within confined areas.
Cable Transmission Media Comparison
Cable Transmission Media Comparison
|
Media
|
Cost
|
Ease
of Installation
|
Capacity
Range
|
Attenuation
|
Immunity
from Interference
|
|
Unshielded
Twisted Pair
|
Extremely Low
|
Very simple
|
1 to 100 Mbps
|
High, maximum effective range in
100s of meters
|
Low
|
|
Shielded
Twisted Pair
|
Moderate
|
Simple to moderate
|
1 to 155 Mbps
|
High, maximum effective range in 100s of
meters
|
Moderately low
|
|
Coaxial cable
|
Low to moderate
|
Simple
|
Varies by size and composition
between 1 Mbps to Gbps
|
High, maximum effective range in low
Kms
|
Moderate
|
|
Fiber Optic Cable
|
Moderate to high
|
Difficult
|
10 Mbps to Gbps
|
High, maximum effective range in 10s of Kms
|
High
|
Subscribe to:
Posts (Atom)