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Faculty of Computer Science & Engineering

Faculty of Computer Science & Engineering. Chapter 02. Radio Frequency. Formation of Radio Frequency.

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Faculty of Computer Science & Engineering

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  1. Faculty ofComputer Science & Engineering Chapter 02. Radio Frequency

  2. 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 ?

  3. Formation of Radio Frequency

  4. Objectives • Questions about the waves? • Wave mechanics of natural • Concept • Amplitude • Wave length • Phare • Cycle • Frequency

  5. 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.

  6. Objectives • RF Behaviors • ■ Gain • ■ Loss • ■ Reflection • ■ Refraction • ■ Diffraction • ■ VSWR • The Units Used In Radio Communication

  7. 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 ……?

  8. 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 .

  9. Wave mechanics of natural

  10. 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

  11. 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.

  12. Amplitude • Amplitude is high, the strength or power of the wave

  13. Wavelength • Wavelength is the distance between two points on two similar consecutive wave crests

  14. Phase

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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

  20. 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

  21. 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

  22. 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.

  23. Electromagnetic waves and radio communication. • The radio waves are classified into the following categories

  24. 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

  25. 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

  26. Electromagnetic waves and radio communication. • Man-made radio waves like? • Principles of operation of a radio transmitter

  27. Electromagnetic waves and radio communication.

  28. 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

  29. Modulation methods • Definition digital • Digital data • Analog data • Digital data • Digital signal • Analog signal • Analog data • Digital signal • Analog signal

  30. 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

  31. Modulation methods

  32. Modulation methods • Modulated at the analog data: • AM (Amplitude Modulation) • FM (Frequency Modulation) • PM (Phase Modulation)

  33. Modulation methods

  34. 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

  35. RF Behaviors • GAIN • Increase in an RF signal's amplitude. • Conventional amplifier is an active process • But the process is passive amplification can occur.

  36. RF Behaviors

  37. RF Behaviors • LOSS • Described as the decline of signal strength • There are many causes of the radio wave attenuation

  38. RF Behaviors

  39. 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.

  40. RF Behaviors

  41. RF Behaviors • Refraction • Refraction occurs when an RF signal changes speed and is bent while moving between media of different densities.

  42. RF Behaviors

  43. RF Behaviors • Diffraction is often caused by buildings, small hills, and other larger objects in the path of the propagating RF signal.

  44. RF Behaviors

  45. RF Behaviors • VSWR

  46. 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

  47. RF Behaviors • Solutions for VSWR • Never use a cable to a device 75 Om 50 Om cable • The equipment needs to be synchronized

  48. 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)

  49. 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

  50. 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

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