Microwaves Applications

its about the paractical applications of microwaves

1. Microwaves Presented By: Muhammad Umer Shehzad Jawad Fakhir Submitted To: Sir Haissam Sattar

2. Contents Introduction to Microwaves Properties of Microwaves Advantages/Disadvantages of Microwaves Waveguide Applications of Microwaves Microwave oven Radar Wireless Mobile Charging Others Applications

3. Waves In physics, a wave is disturbance or oscillation that travels through matter or space, accompanied by a transfer of energy. There are two main types of waves . Mechanical Waves Electromagnetic Waves Radio waves Microwaves Infrared radiation Visible light Ultraviolet radiation

4. 4 Microwaves are electromagnetic waves Frequency range 300MHz- 300Ghz Wavelengths range in air 100cm- 1mm The word microwave means “very short wave” Microwaves is the shortest wavelength region of the radio spectrum and a part of the electromagnetic spectrum Microwaves

5. 5 Microwaves Frequency Bands

6. Properties of Microwaves 6 1.Electromagnetic radiation of short wavelength 2.Can reflect by conducting surface like optical waves. 3.M.W current flows through outer layer of conductor 4.Microwaves are easily attenuated 5.They are not reflected by ionosphere

7. 7 Microwaves have large bandwidths Improved Directive properties.Can be focused in a specified direction Fading effect and reliability. Due to LOS and high frequency fading effect is very low Transmitter/Receiver power requirements are pretty low at microwave frequencies Advantages and Limitations

8. 8 Advantages and Limitations Microwave band ranging from 300MHz-10GHz are capable of freely propagating through atmosphere This helps in astronomical research of space in the study of microwave radiations from the sun and stars

9. A dvantages of Microwave communication Because of high frequency, more data can be sent. High bandwidth,higher speeds Because of their short wavelength,microwaves use smaller antennas Smaller antennas produce a more focused beam

10. Disadvantages of microwave communication They require no obstacle is present in the transmission path The cost of implementing the communication infrastructure is high Microwaves are susceptible to rain,snow,electromagnetic interference

11. Functional Block Diagram of a Communication System Input signal (Audio, Video, Data) Input Transducer Transmitter Output Transducer Receiver Output signal (Audio, Video, Data) Channel Electrical System Wire or Wireless

12. Antenna and Wave Propagation Surface Wave Direct Wave Sky Wave Satellite communication Microwave & Millimeter Wave Earth Ionsphere Transmitting Antenna Receiving Antenna Repeaters(Terrestrial communication) 50Km@25fts antenna

13. 13 A Hollow metallic tube of uniform cross section for transmitting electromagnetic waves by successive reflections from the inner walls of the tube is called waveguide . Waveguide

14. 14 Why we need Waveguide?? Electromagnetic waves at frequencies greater than 3GHz; transmission through cables becomes difficult. Reason This is due to losses in the solid cable and the dielectric use to support the cable. So, we use waveguide which is a hollow metallic

15. 15 Basic features Waveguides are used to carry energy from one equipment to another e.g. In Antennas transmitter power to antenna and microwave signal from antenna to receiver Waveguides are made from copper, aluminum or brass The metals are extruded into long rectangular or circular pipes The energy to be transmitted is injected from one end of the waveguide through probes The electric and magnetic field of signals bounce off the walls back and forth.

16. 16 Em field configuration within the waveguide EM field configuration can be determined from Maxwell’s equation. There are number of configurations and each configuration is known as mode. Possible modes Transverse Electromagnetic Transverse Electric Transverse Magnetic Hybrid

17. Components of Electric and Magnetic Field Intensities in an EM wave 17

18. 18 2. Transverse Electric (TE) wave: Here only the electric field is purely transverse to the direction of propagation and the magnetic field is not purely transverse. (i.e.) E z = 0, H z ≠ 0 Possible types of Modes 1.Transverse Electro Magnetic (TEM) wave : Here both electric and magnetic fields are directed components.(i.e.) Ez=0 and Hz=0 2.Transverse Electric (TE) wave : The electric field component is purely transverse to the direction of propagation.(i.e.) Ez=0 and Hz  

19. 19 Possible types of Modes 3.Transverse Magnetic (TM) wave : The magnetic field component is purely transverse to the direction of propagation.(i.e.) Ez 0 and Hz   4.Hybrid (HE) wave: Here neither electric nor magnetic fields are purely transverse to the direction of propagation.(i.e.) Ez 0 and Hz  

20. 20

21. 21 Rectangular Waveguides Any shape of cross section of a waveguide can support electromagnetic waves of which rectangular and circular waveguides have become more common. A waveguide having rectangular cross section is known as Rectangular waveguide

22. 22 Rectangular waveguide Dimensions of the waveguide which determines the operating frequency range

23. 23 1.The size of the waveguide determines its operating frequency 2.The frequency of operation is determined by dimension ‘a’ which is usually made one half the wavelength at lowest frequency of operation. 3.At cutoff frequency and below, the waveguide will not transmit energy. Dimensions of the waveguide which determines the operating frequency range:

24. 24 Wave paths in a waveguide at various frequencies At high frequency (b) At medium frequency ( c ) At low frequency (d) At cutoff frequency

25. 25 Wave propagation When a probe launches energy into the waveguide, the electromagnetic fields bounce off the side walls of the waveguide as shown in the above diagram. The angles of incidence and reflection depend upon the operating frequency. At high frequencies, the angles are large and therefore, the path between the opposite walls is relatively long as shown in Fig.

26. 26 At lower frequency, the angles decrease and the path between the sides shortens. When the operating frequency is reaches the cutoff frequency of the waveguide, the signal simply bounces back and forth directly between the side walls of the waveguide and has no forward motion. At cut off frequency and below, no energy will propagate.

27. 27 Flexible Waveguide It is used for bends, twists or in applications where certain criteria may not be fulfilled by normal waveguides. Figure below shows some of the flexible waveguides:

28. Applications of Microwaves

29. How a Microwave Oven Works?

30. History Invented Accidentally By Dr. Percy Lebaron Spencer.

31. Working Principle 31 Microwave radiations generated by a magnetron pass through the exposed food, create dielectric heating within the food, this is the basic principle on which a microwave oven works. Dielectric Heating

32. How the Oven Works Electricity from the wall outlet travels through the power cord and enters the microwave oven through a series of fuse and safety protection circuits When the oven door is closed, an electrical path is also established through a series of safety interlock switches

33. Sensing That All Systems Are Set To Go, The Signal Activates Triac Producing A Voltage Path To The High-voltage Transformer. The High-voltage Transformer Along With A Special Diode And Capacitor Arrangement Increases The Typical Household Voltage From ~220 Volts To ~3000 Volts

34. The magnetron converts the high voltage into the microwave frequency for cooking. The microwave energy is transmitted into a waveguide. The waveguide feeds the energy to the stirrer blade and into the cooking area. When the door is opened, or the timer reaches zero, the microwave energy stops.

35. How Foods Get Cooked The microwaves that penetrate the food have an electric field that oscillates 2.45 billion times a second, a frequency that is well absorbed by polar liquid molecules such as water, sugars, fats and other food molecules. Water interacts with the microwave: flipping its orientation back and forth very rapidly bumping into one another and producing heat, cooking the food.

36. Radar 37

37. Introduction 38 Radar Radio Detection and Ranging A System For Detecting The Presence, Direction, Distance, And Speed Of Aircraft, Ships, And Other Objects, By Sending Out Pulses Of Radio Waves Which Are Reflected Off The Object Back To The Source. The Time Delay Between The Transmitted Pulse And The Received Echo Can Be Used To Determine The Distance To The Target .  

38. Basic Principle and Operation Of Radar

39. RADAR FUNCTIONS TRANSMITTER: Generate radio waves Perform modulation Amplification to high power RECIEVER: High sensitivity Very low noise Ability to discern a received signal from background noise PROCESSING & CONTROL: It regulates the rate at which pulses are sent (PRF). Synchronizes the function between Transmitter, Receiver, display, duplexer etc.

40. DUPLEXER: A switch to alternatively connect Tx and Rx to antenna. ANTENNA: Takes radar pulses from transmitter and puts into the air. Focuses energy into the well designed beam. Antenna is of two types Physically moving Electronically steered DISPLAY: Display received information to the operator. It is of two types PPI Used for surface search and navigation A-Scan Used for gunfire control

41. MAIN TYPES OF RADAR There are two main types of radar: 1)Primary Radar Continuous wave Radar Pulse Radar 2)Secondary Radar SSR

42. 43 1)CONTINUOS WAVE RADAR: Employs continual RADAR transmission Separate transmit and receive antennas Relies on the “DOPPLER SHIFT”

43. 44 2)PULSE RADAR: The PULSE radar is the more conventional radar, which transmits a burst of radar energy and then waits for the energy (or echo) to be reflected back to the antenna. Since radar waves travel at the speed of light, range from the return can be calculated.

44. Applications of Radar

45. MILITARY Target Detection, Target Tracking & Weapon Control Tracks The Targets, Directs The Weapon To An Intercept And Assess The Effectiveness Of Engagement

46. Weather Observation Planetary Observation Below Ground Probing REMOTE SENSING

47. Used To Safely Control Air Traffic In The Vicinity Of The Airports. Mapping Of Regions Of Rain In The Vicinity Of Airports & Weather. AIR TRAFFIC CONTROL

48. Radar Speed Meters Are Used By Police For Enforcing Speed Limit. LAW ENFORCEMENT & HIGHWAY SAFETY

49. Airborne Weather Avoidance Radar Outlines The Regions Of Precipitation & Dangerous Wind Shear Low Flying Military Aircrafts Rely On Terrain Avoidance & Terrain Following Radars To Avoid Collision With High Terrain & Obstructions AIRCRAFT SAFETY & NAVIGATION

50. Radar Is Found On Ships & Boats For Collision Avoidance & To Observe Navigation Buoys, When The Visibility Is Poor Shore Based Radars Are Used For Surveillance Of Harbours & River Traffic SHIP SAFETY

51. Space Vehicles Have Used Radar For Landing On The Moon And Other Planets. Used For Planetary Exploration Ground Based Radars Are Used For Detection & Tracking Of Satellites & Other Space Objects Used For Radio Astronomy SPACE

52. MINE INSPECTION

53. LOCATING UNDER GROUND PIPES

54. Wireless Charging of Mobile Phones Using Microwaves 55

55. INTRODUCTION Objective —to Recharge Any Mobile Phone Independent Of Particular Mobile Charger. Mobile Phones Becoming Basic Part Of Life Recharging Of Mobile Phones Is A Big Problem More You Talk More The Mobile Get Charged! No Separate Mobile Charger Additives To Mobile Handsets: Sensor Rectenna 56

56. Microwave region of electromagnetic spectrum We choose s –band of microwave region(2-4GHz) We Use License free 2.45 GHz Industrial, Scientific and Medical ( ISM) radio bands 57 Designation Frequency range L Band 1 to 2 GHz S Band 2 to 4 GHz C Band 4 to 8 GHz X Band 8 to 12 GHz Ku Band 12 to 18 GHz K Band 18 to 26 GHz Ka Band 26 to 40 GHz Q Band 30 to 50 GHz U Band 40 to 60 GHz

57. Principle of Operation & Block Diagram Transmitting station with the microwave transmitter sensor Rectenna RF cable circulator waveguide Slotted waveguide Antenna mobile signal Microwave signal is transmitted from transmitter along with message signal using slotted waveguide antenna at frequency 2.45 GHZ. The sensor search for the mobile signal , in addition it has a “RECTENNA”. Rectenna receives the transmitted power and converts the microwave power to DC power.

58. TRANSMITTER SECTION Consists of two parts Magnetron Slotted waveguide antenna 59

59. MAGNETRON Magnetron is a vacuum tube oscillator that generates high-power electromagnetic signals in the microwave frequency range. 60

60. Working Principle 61 When a charge/charge particle accelerates in space, it generates electromagnetic waves. This statement is the derivation of Maxwell’s law which says that a classical electromagnetic radiation is ultimately generated when a charged particle is accelerated through space.

61. Working 62

62. Slotted waveguide antenna It is an Omni-directional Antenna. It is used as ideal power transmitter (because of its high aperture efficiency >95%) . It has high power handling capacity .

63. RECEIVER SECTION Basic additions to mobile phone Sensor Rectenna 64

64. SENSOR Simple circuit which detects whether the user is making a call Simple F to V converter, this would serve our purpose Operating frequency of mobile phone operators for GSM system for mobile communication in Pakistan is 900MHZ to 1800MHZ Simple yet powerful F to V converter is LM2907 On the reception of the microwave signal ,the sensor circuitry directs rectenna circuit to ON Rectenna circuit converts microwave energy to dc output Mobile phone begins to charge using the microwave power as long as the user talks over cell phone.

65. RECTENNA A rectifying antenna called a rectenna receives the transmitted power and converts the microwave power to direct current (DC) power. The Schottky diode rectifies the AC current induced in the antenna by the microwaves, to produce DC power, which powers a load connected across the diode.  Schottky diodes are usually used because they have the lowest voltage drop and highest speed and therefore have the lowest power losses due to conduction and switching. Circuit Design

66. Implementation Recently NOKIA has launched this wireless charging technology in its new recent mobile model “ NOKIA LUMIA 1020”.

67. Advantages The need of different types of chargers by different manufacturers is totally eliminated Lower risk of ELECTRICAL SHOCK or shorting . Convenience. Get Charged as we make call. Only one microwave transmitter can serve to all the service providers in that area.

68. Disadvantages Wireless transmission of the energy causes some drastic effects to human body, because of its radiation. Process is of high cost. Network Traffic may Cause Problem in charging

69. Other Applications Of Microwaves 70

70. Homeland Security Applications Potential Security Applications Detection of hidden weapons and explosives Detecting non-metallic weapons Postal screening of envelopes for bacteria Chem/bio detection Security screening wand Explosives Stand-off detection Postal screening Envelope

71. Terahertz Images Can Reveal Objects Concealed Under Cloth, Paper, Tape, Even Behind Walls Objects Concealed Under clothes Knife Wrapped in Newspaper

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