FACULTY OF COMPUTER SCIENCE & ENGINEERING Chapter 02. Radio Frequency
Jan 01, 2016
FACULTY OF
COMPUTER SCIENCE & ENGINEERING
Chapter 02. Radio Frequency
FORMATION OF RADIO FREQUENCY
Carrier Wave is Sin signal have high
frequency in which it will have components
such as phase or amplitude will vary
according to the signal wave, waves to
create high-rise to bring these signals in
space Do you understand ?
FORMATION OF RADIO FREQUENCY
OBJECTIVES
Questions about the waves?
Wave mechanics of natural
Concept
Amplitude
Wave length
Phare
Cycle
Frequency
OBJECTIVES
Formation Of Electromagnetic Waves
Electric Fields
Magnetic Fields
Electromagnetic Fields
Electromagnetic Waves And Radio Communication
The Operation Of The Radio Waves
Concept Carrier Wave
Modulation methods Carrier Wave
Frequency range of applications in wireless media.
OBJECTIVES
RF Behaviors
■ Gain
■ Loss
■ Reflection
■ Refraction
■ Diffraction
■ VSWR
The Units Used In Radio Communication
QUESTIONS ABOUT THE WAVES?
What is the wave ?
What is the shape wave ?
How is the wave active ?
Define of Amplitude, Cycle, Frequency, Phase
What is bandwidth? What frequency band?
What is 3G , GSM ,CDMA ……?
QUESTIONS ABOUT THE WAVES?
Why do we hear the sound coming from far away?
Why do we listen to the radio at night better normal?
Why do we communicate with each other via
phone ?
Why was the data transmitted through outer space ?
We want to watch TV, listen to the radio antenna
must be why?
Meaning of UHF, VHF .
WAVE MECHANICS OF NATURAL
WAVE MECHANICS OF NATURAL
For waves on the water above, the oscillation
perpendicular to the direction of wave
propagation. It is the shear wave
Has the oscillation wave coincides with that
of wave propagation along the wave.
Sound waves as we speak, it is a longitudinal
wave
RF CHARACTERISTICS
All RF waves have characteristics that vary to define the wave.
Some of these properties can be modified to modulate information onto the wave. These properties
are wavelength, frequency, amplitude, and phase.
AMPLITUDE
Amplitude is high, the strength or power of the wave
WAVELENGTH
Wavelength is the distance between two points on two similar consecutive wave crests
PHASE
CYLE, FREQUENCY
What cycle? What is the frequency?
Frequency is the number of vibrations per
unit time and is equal to f = 1 / T. Longer
period is the time to perform a full oscillation.
CYLE, FREQUENCY
The impact of frequency usage on WLANs is
tremendous. By using different frequencies,
you can enable distinct connections or RF links
in a given coverage area or cell. For example,
an IEEE 802.11g network using channel 1 can
exist in the same cell as an IEEE 802.11g
network using channel 11. This is because
these channels use different frequencies that
do not cancel or interfere with each other.
SOUND WAVES AND SOUND FEELINGS
Example :
When you shake a piece of mild steel plates that we found
lower vibration
When we rung steel plate with a larger force
Ears begin to hear a certain gently, that is, pieces of steel
that has a sound start
Human ear is sensing the oscillation frequency from
about 16Hz to 20.000Hz.
Sound waves in any solid, liquid, gas
Mechanical waves with frequencies greater than
20.000Hz called ultrasonic
ELECTROMAGNETIC WAVES
An electromagnetic wave is a propagating combination
of electric and magnetic fields.
In terms of nature, electricity and magnetism
are manifestations of a separate unified field
called electromagnetic fields
ELECTRIC FIELDS
Example :
When an AC is running. It immediately
generates an electric field around it
In general the electric field is the physical
environment surrounding the special charge
In terms of nature, electricity and magnetism
are manifestations of a separate unified field
called electromagnetic fields
MAGNETIC FIELDS
Example :
When an AC is running. We move the wires of
the electric current is running. It immediately
generates a magnetic field.
In terms of nature, electricity and magnetism
are manifestations of a separate unified field
called electromagnetic fields
ELECTROMAGNETIC WAVES
Principle Macxoen
Electromagnetic field due to a charge of vertical
vibrations generated at O will spread in space as
waves. Wave which is called electromagnetic waves.
Hecxo the first to develop the electromagnetic wave
The velocity of electromagnetic waves is
300.000km/s. Coincides with the velocity of the light
ELECTROMAGNETIC WAVES AND RADIO COMMUNICATION.
Applications of Electromagnetic waves :
Rada
Radio astronomy
Radio-controlled
In the radio communication
Waves with frequencies from thousands hectares
or more, known as radio waves.
ELECTROMAGNETIC WAVES AND RADIO COMMUNICATION.
The radio waves are classified into the
following categories
ELECTROMAGNETIC WAVES AND RADIO COMMUNICATION.
Characteristics of waves :
Long and ultra long wave
Less water absorption
They are used to communicate underwater
Normal wave
During the day they are strongly absorbed by the
ionosphere, so far not been transmitted So the night medium wave radio better day
ELECTROMAGNETIC WAVES AND RADIO COMMUNICATION.
Characteristics of waves :
Short wave ( Microwave)
They are reflective ionosphere on the ground
So a short radio stations with large capacity can wave
to all locations on the ground.
Supper Short wave ( Microwave)
The microwave has the largest energy
Ionosphere are not absorbed or reflected
Used in information space
ELECTROMAGNETIC WAVES AND RADIO COMMUNICATION.
Man-made radio waves
like? Principles of operation of a radio transmitter
ELECTROMAGNETIC WAVES AND RADIO COMMUNICATION.
ELECTROMAGNETIC WAVES AND RADIO COMMUNICATION.
High-frequency waves is called carrier
Carrier Wave is Sin signal have high
frequency in which it will have components
such as phase or amplitude will vary
according to the signal wave, waves to
create high-rise to bring these signals in
space
MODULATION METHODS
Definition digital
Digital data
Analog data
Digital data
Digital signal
Analog signal
Analog data
Digital signal
Analog signal
MODULATION METHODS
Vary amplitude call amplitude
Vary frequency call frequency
Vary phare call phare
Modulated at the digital data:
Amplitude Shift Keying – ASK
Frequency Shift Keying- FSK
Phase Shift Keying –PSK
MODULATION METHODS
MODULATION METHODS Modulated at the analog data: AM (Amplitude Modulation) FM (Frequency Modulation) PM (Phase Modulation)
MODULATION METHODS
RF BEHAVIORS
RF waves that have been modulated to contain information are called RF signals. These RF signals have behaviors that can be predicted and detected
■ Gain
■ Loss
■ Reflection
■ Refraction
■ Diffraction
■ Scattering
■ VSWR
RF BEHAVIORS
GAIN Increase in an RF signal's amplitude.
Conventional amplifier is an active process
But the process is passive amplification can
occur.
RF BEHAVIORS
RF BEHAVIORS
LOSS Described as the decline of signal strength
There are many causes of the radio wave
attenuation
RF BEHAVIORS
RF BEHAVIORS
Reflection When an RF signal bounces off of a smooth,
nonabsorptive surface, changing the
direction of the signal, it is said to reflect and
the process is known as reflection.
RF BEHAVIORS
RF BEHAVIORS
Refraction Refraction occurs when an RF signal changes
speed and is bent while moving between
media of different densities.
RF BEHAVIORS
RF BEHAVIORS
Diffraction is often caused by buildings, small
hills, and other larger objects in the path of
the propagating RF signal.
RF BEHAVIORS
RF BEHAVIORS
VSWR
RF BEHAVIORS
Voltage Standing Wave Radio
VSWR values are often found to be 1.5: 1
EX:
1:1 VSWR value combination perfect
impedance
Influence VSWR
Reduce the amplitude of radio waves
This capacity can burn the circuit area
RF BEHAVIORS
Solutions for VSWR
Never use a cable to a device 75 Om 50 Om
cable
The equipment needs to be synchronized
RADIO FREQUENCY MATHEMATICS
There are four parameters are calculated in
the WLAN:
Power at the transmitting device
The attenuation and amplification devices
connected
Capacity at the last connector before the
antenna
Power at the antenna elements (EIRP)
RADIO FREQUENCY MATHEMATICS
W (Watt) of the basic unit of power is Watt
(W)
1 W is defined as an electric current is 1 A
and 1 V
EX:
Light used 120 V will have 7 W.
In a totally dark 7W bulb is visible from about 83
km away from it in all directions
RADIO FREQUENCY MATHEMATICS
Miliwatt ( mW)
Often, the power level of WLAN rarely exceed
100 mW
100 mWcan transmitting data to 0.8 km
1 W= 1000 mW
RADIO FREQUENCY MATHEMATICS
Units of dB and dBm
Measurement Units amplification and
attenuation
Unit dBm is a unit of absolute power
RADIO FREQUENCY MATHEMATICS
Have unit conversion table as follows
RADIO FREQUENCY MATHEMATICS
EX: Transfer from dBm to W units
We have 43 = 10 + 10 + 10 +10 + 3
So infer
10 dBm based on the first panel would be 10 mW
Or 1mW x 10 = 10 mW
10mW x 10 = 100 mW
100 mW x10 = 1000mW
1000mW x 10 = 10,000 mW
10,000mW x2 = 20,000 mW = 20 W
RADIO FREQUENCY MATHEMATICS
Unit dBi
Amplification antenna
The END