Transcript Radio Frequency Components, Measurements, and Mathematics

Chapter 3
Radio Frequency Components,
Measurements, and Mathematics
Key Terms & Concepts
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3 Basic Requirements for
Communication
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Two or more devices want to communicate
Medium or method for them to
communicate
Set of rules for them to use
Key Terms & Concepts
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Transmitter
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Generates signal at specific frequency
Determines amplitude (power level) of
signal
Antenna
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Collects AC signal that receives from
transmitter
Directs, or radiates, RF waves away from
the antenna in a specific pattern
Key Terms & Concepts
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Receiver
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Receives the signal from the antenna and
translates the signal into 1s and 0s
Intentional Radiator (IR)
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Specifically designed to generate RF
Consists of all components from
transmitter to antenna, excluding antenna
Key Terms & Concepts
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Equivalent Isotropically Radiated Power
(EIRP)
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Highest RF signal strength transmitted
from antenna
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Focuses the RF generated by the IR and makes
it stronger
Key Terms & Concepts
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Units of Power
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Watt
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1 Watt = 1 ampere (amp) of current flowing at 1 volt
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Milliwatt (mW)
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Amp is current
Voltage is pressure generated
Amount of watts generated = volts X amps
1/1,000 of a watt
Decibels relative to 1 milliwatt (dBm)
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Compares signal to 1 milliwatt of power
0 dBm = 1 milliwatt
Key Terms & Concepts
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Units of Comparison
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Decibel (dB)
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Milliwatts
Represents difference
btw 2 values
Decibels isotropic
(dBi)
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Gain or increase of
power from an
antenna when
compared to what an
isotropic radiator
would generate
.01
.1
1
10
100
1000
10000
Decibel
change
-20
-10
0
+10
+20
+30
+40
Key Terms & Concepts
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Units of Comparison
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Decibels dipole (dBd)
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Increase in gain of an antenna when it is
compared to the signal of a dipole antenna
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If antenna has value of 3 dBd, it is 3 dB greater than
a dipole antenna