faculty of computer science & engineering

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

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




MAGNETIC FIELDS

Example :

When an AC is running. We move the wires of

the electric current is running. It immediately

generates a magnetic field.




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.


The radio waves are classified into the

following categories


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


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


Man-made radio waves

like? Principles of operation of a radio transmitter


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)


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


Miliwatt ( mW)

Often, the power level of WLAN rarely exceed

100 mW

100 mWcan transmitting data to 0.8 km

1 W= 1000 mW


Units of dB and dBm

Measurement Units amplification and

attenuation

Unit dBm is a unit of absolute power


Have unit conversion table as follows


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


Unit dBi

Amplification antenna

The END

faculty of computer science & engineering

Documents

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