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جامعة النجاح الوطنية كلية العلوم قسم الفيزياء / فرعي إلكترونيات PowerPoint Presentation
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جامعة النجاح الوطنية كلية العلوم قسم الفيزياء / فرعي إلكترونيات

جامعة النجاح الوطنية كلية العلوم قسم الفيزياء / فرعي إلكترونيات

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جامعة النجاح الوطنية كلية العلوم قسم الفيزياء / فرعي إلكترونيات

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  1. جامعة النجاح الوطنيةكلية العلوم قسم الفيزياء / فرعي إلكترونيات 2013 Presented by : AnharHamadneh TO : Dr. Issam Al Ashqar


  3. Microwaves Definition • Microwaves; areelectromagnetic waves with • wavelengths ranging from as long as one meter 1m to as short as one millimeter 1 mm, or equivalently. • frequencies between 300 MHz (0.3 GHz) and 300 GHz.This definition includes both UHF and EHF (millimeter waves),. In all cases, microwave includes the SHF band (3 to 30 GHz, or 10 to 1 cm) at minimum, See fig,, 1

  4. Electromagnetic Spectrum Source from Hyper Physics

  5. Microwaves used for lots of things…. • Microwaves communications. Ex - cell phones. • radar. • microwave ovens. • astronomy . • Heating . TO see full text about microwave heating click TO see full text about microwave heating click


  7. Microwave base • Microwave is EM wave. • EM wave is transverse wave. See fig ’a’ Fig ‘a’

  8. It is made up of magnetic and electric fields that are at right angles to each other and at right angles to the direction of propagation. It travels in a straight line at approximately the speed of light. See fig below

  9. Microwave transmission • Microwave dishes are commonly used to transmit data over long distances. A dish-to-dish microwave setup could easily cover 4 miles. • It relies on high frequency microwave radiation that travels at the speed of light. Microwaves get weaker as they get further away from their source, they also need to be line-of-sight so a large building in the way would tend to block the signal. • The microwave dishes would need to be installed by a professional contractor which would add to the already high cost of equipment.

  10. Advantages: • Can cover large distances over rough terrain where you could'nt bury cables. • High speeds. • wide bandwidth • multichannel transmissions • Disadvantages: • Equipment very expensive . • Relies on line-of-sight . • Can be prone to interference such as passing airplanes and rain.

  11. Groundmicrowaves{Terrestrial} • transmission systems consisting of at least two radio transmitter/receivers., connected to high gain antennas (directional antennas which concentrate in electromagnetic field) focused in pairs on each other. • The operation is point-to-point-communications are established between two antennas with line-of-sight visibility. • This can be contrasted to point-to-multipoint systems like broadcast radio or television.


  13. How Terrestrial (ground) Microwave Transfer and Receive Data • Terrestrial(GROUND) microwave communication employs Earth-based transmitters and receivers to transfer and receive data. • The frequencies used are in the low-gigahertz range, which limits all communications to line-of-sight. • Example of terrestrial {ground}microwave equipment -telephone relay towers, which are placed every few miles to relay telephone signals cross country.

  14. Radio An Antenna is : An effective interface between the radio and free space: Free space Antenna For Terrestrial Communications, antennas must be directional: Radio http//

  15. Formula Parabolic Antenna Directive Gain Ga(dBi) = 10 log10h [ 4 p Aa /l2 ] Where: Ga = Antenna Directive Gain (Catalog spec) h = Aperture Efficiency (50-55%) Aa= Antenna Aperture Area l= Wavelength (speed of light / frequency)

  16. Advantages of Terrestrial(ground ) Microwave over Satellite • Lower cost • Reduced latency • Reduced Size & Weight

  17. Satellite microwaves • Space station that receives microwave signals from earth-based station, amplifies signals and broadcasts signals back to a number of earth-based stations • .. Transmitted waves can be received on the all ground through a satellite antenna. ..

  18. Satellite Microwave Transmission • a microwave relay station in space • can relay signals over long distances • geostationary satellites • remain above the equator at a height of 22,300 miles (geosynchronous orbit) • travel around the earth in exactly the time the earth takes to rotate

  19. Satellite Transmission Process satellite Transponder in speac dish dish 22,300 miles uplink station downlink station

  20. Satellite Communications in a geosynchronous orbit A special form of microwave communications Signals sent from the ground to a satellite; Then relayed to its destination ground station • Long propagation delay • Due to great distance between ground station and satellite (Even with signals traveling at light speed)

  21. Relies on line-of-sight .

  22. Apartment Buildings Gas Stations Corporate Offices Residential Branch Offices Emergency Response

  23. Microwaves Satellite FORMS

  24. Cell Phone Frequency Range: 850 and 1900 MHz

  25. Microwave in radar Radar_ antenna

  26. Radar Definition Radar is a system that uses electromagnetic waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations.

  27. Radar using • Radar is used in many contexts; • including meteorological detection of precipitation. • measuring ocean surface waves. • air traffic control. • police detection of speeding traffic. • by the military.

  28. Radar Principles • Reflection . • Polarization . • Interference . • Noise . • Clutter . • Jamming

  29. microwave ovens

  30. microwave ovens Principles microwave oven works by passing non-ionizing microwave radiation, usually at a frequency of 2.45 gigahertz (GHz)—a wavelength of 122 millimetres (4.80 in)—through the food. Microwave radiation is between common radio and infrared frequencies. Water, fat, and other substances in the food absorb energy from the microwaves in a process called dielectric heating

  31. microwave ovens…works + • Water is a polar molecule mean a positive charge at one end and a negative charge at the other,. result,, This means it will try to orient itself a particular way in alternating electric field of the microwaves..,,, This molecular movement represents heat.  + H2o molecule

  32. Microwave Oven works.. cont oscillating electric field Water oscillating with time in electric field = heat time

  33. Difference between Cell Phone and Microwave Oven • Power • Cell Phone 0.1 Watts • Microwave ovens 1000 Watts • Modulation • Cell phone is carrying info • Microwave is not

  34. THANKS!!