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Chapter 3 - Radio Frequency Components and Measurement : - Coggle Diagram
Chapter 3 - Radio Frequency Components and Measurement :
Component of RF communications
Antenna
Provides two functions in a communication
system.
When connected to the transmitter ,it collects AC signal that it receives from the transmitter and directs or radiates the RF waves away from the antenna in a pattern specific to the antenna type.
When connected to the receiver the antenna take the RF waves that it receives through the air and directs the AC signal to the receiver.
The receiver converts the AC signal to bits and bytes
Receiver
Receives the signal from the antenna and
translates the signal into 1s and 0s.
It then takes this data and passes it to the
computer to be processed.
It is not an easy job
This signal that is received is a much less powerful signal that what was transmitted because of distance it has traveled and the
effect of free spaces path loss (FSPL)
Transmitter
The initial components in the creation of the
wireless medium.
Generates signal at specific frequency
Determines amplitude (power level) of signal
The Computer hands the data off to the transmitter, and it is the transmitter's job to begin the RF communication
The transmitter takes data provided and
modifies the AC signal by using a modulation
techniques to encode the data into signal.
Equivalent isotropically radiated
power (EIRP)
Highest RF signal strength transmitted from antenna.
Focuses the RF generated by the IR and makes it stronger.
A measure of the amount of actual power emitted from an antenna.
The isotropy in EIRP describes an ideal situation whereby the radio energy is assumed to be equally distributed in all directions
It is the sum total of the power output from the IR and the passive gain (or loss) caused by the antenna.
Intentional Radiator (IR)
Specifically designed to generate RF.
Consists of all components from transmitter
to antenna (such as the transmitter,
amplifiers, cables, and other knobs and dials
found in wireless devices) excluding
antenna.
A device that intentionally generates and and
emits radio frequency energy by radiation or
induction
It measured in miliwatts(mW)
Cordless phones, walkie-talkies, and wireless
cards are all good examples of Irs.
Isotropic radiator
3 Basic Requirements for Communication
Two or more devices want to communicate
Set of rules for them to use
Medium or method for them to
communicate
Units of Power
WATT
'1 Watt = 1 ampere (amp) of current
flowing at 1 volt
Amp is current
Voltage is pressure generated
Amount of watts generated = volts X amps
Milliwatt (MW)
1/1,000 of a watt
Decibels relative to 1 milliwatt (dBm)
Compares signal to 1 milliwatt of power
0 dBm = 1 milliwatt
Unit of Comparison
Decibel (dB)
Represents difference btw 2 values
Decibels isotropic (dBi)
Gain or increase of power from an antenna when compared to what an isotropic radiator would generate
Decibels dipole (dBd)
Increase in gain of an antenna when it is compared to the signal of a dipole antenna
If antenna has value of 3 dBd, it is 3 dB greater than a dipole antenna
