Mw day 1

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1935 – Heil oscillator
1939 – klystron amplifier
1944 – Helix type TWT
In the early 1950s – low power output of linear beam tubes to high power levels
Finally invention of Magnetrons
Several devices were developed – two significant devices among them are
1) extended interaction klystron
2) Twystron hybrid amplifier


CYLINDRICAL
LINEAR
COAXIAL
VOLTAGE-TUNABLE
INVERTED COAXIAL
FREQUENCY-AGILE COAXIAL

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  • 다른점
    - injection current 가 barrier 넘어로 thermionic emission을 통해야 한다는 점
    - avalanche current와 같지 않게 BARITT diode injection current는 injection phase delay를 가지지 않음
  • 전압이 depletion edge meet까지 가면, punch-through가 일어난다
    Junction
  • Schottky-barrier injection에서 (a)는 under thermal equilibrium이고 (b)는 punch-through에서 이고, (c)는 flat –band condition에서의 상태를 나타낸 것이다.
    Injection cycle에서 bias 는 Vpt와 Vfb사이이다.
    P-n junction의 경우 Øbp=0
  • (a)는 trminal 전압 이고, (b)는 injection current이고, (c) terminal current 의 파형이다
    라모 쇼클리 이론에 의하면 L부분에 위치한 두개의 일렉트로드에서 움직이는 charge 는 터미널 전류를 야기시킨다
    전압이 계속 positive cycle이기 때문에 이 부분에서 전류의 일부는 dissipative하다. 이것이 IMPATT diode 와 비교해 BARITT diode의 reduced efficiency가 더 많이 감소되는 이유이다
    Maximum efficiency는 BARITT diode에서 10%, IMPATT diode 에서는 15%이다
    Terminal current pulse width는 transit time에 의해 결정 된다, 그리고 그것은 ¾ cycle이다
  • BARITT의 파워 프리퀀시 특징에 대해 나타낸 표이다.
    파워는 f의 제곱에 비례하여 감소한다
  • IMPATT와 관련이 있는 에벌런치 전류는 노이즈가 많고, 75~150V나 되는 높은 전압을 필요로 함
    펀치 뜨루 다이오드는 지너 다이오드 우개를 back to back 로 연결해서 대체 할 수도 있음음
  • 이것의 유일한 특징은 나뉘어져 있다는 것이다.
    Heterojunction 에 의해 saturation velocity가 달라진다.
  • (a)는 structure이고, (b)는 피엔 정션 인젝터에서 밴드 투 밴드 터널링 에너지 밴드 diagram이고, (c) 는 쇼트키 배리어 인젝터에서 배리어를 통한 터널링 에너지 밴드 diagram이다.
  • (a)는 structure이고, (b)는 에너지 밴드 diagram이고, (c) 는 레조넌트 터널 다이오드 인젝터의 아이브이 특성.
    8장에서 보았던
  • Mw day 1

    1. 1. EC04 - 702: MICROWAVE DEVICES AND COMMUNICATION By AJAL.AJ Faculty , Dept of ECE METS SCHOOL OF ENGINEERING,MALA
    2. 2. 1. With this paper, student should be able to understand the working principle and use of various microwave components and semiconductor devices. This paper also provides the basic aspects of terrestrial and satellite microwave communication links Objectives: 2.
    3. 3. Module I (13 hours) Basics of microwave Engineering • Theory of waveguide transmission - rectangular waveguides - TE modes - TM modes - waveguide components - rectangular cavity resonator - circular cavity resonator (only basic ideas) - E- plane tee - magic tee - isolator - circulator -directional coupler - S matrix
    4. 4. Module II (13 hours) Microwave tubes • Microwave linear beam tubes - klystron (bunching, output power and loading) -reflex klystron - traveling wave tube (amplification process, convection current, axial electric field, gain) – • Microwave crossed field tubes - magnetron (operation, characteristics and applications)
    5. 5. Module III (13 hours) Microwaves devices • Semiconductor microwaves devices - microwave transistors - tunnel diodes and FETs - transferred electron devices - Gunn effect diodes - (Gunn effect, operation, modes of operation, microwave generation and amplification) - LSA diodes - InP diodes - Cd Te diodes - avalanche transit time devices - read diodes - impatt diodes - trapatt diodes - baritt diodes
    6. 6. Module IV (13 hours) Microwave communication • Terrestrial microwave communication - basic principles of microwave links -link analysis - microwave relay systems - choice of frequency - line of sight and over the horizon systems - modulation methods - block schematic of terminal transmitters and receivers - effect of polarization - diversity receivers - digital microwave links - digital modulation schemes - fading - digital link design -satellite communication - orbit of communication satellites - angle of elevation - propagation delay - orbital spacing - satellite construction - transponders - antennas - multiple spot beams - earth station - link analysis - multiple access schemes - digital satellite links
    7. 7. MODULE 1 Basics of microwave Engineering
    8. 8. Why Going For NewWhy Going For New Wave guidingWave guiding Structures instead ofStructures instead of transmission linestransmission lines ??????
    9. 9. TE & TM ModesTE & TM Modes
    10. 10. Rectangular WaveguidesRectangular Waveguides (Derivation of fields EX ,Ey ,Hx &(Derivation of fields EX ,Ey ,Hx & Hy)Hy)
    11. 11. Waveguide components Rectangular waveguide Waveguide to coax adapter E-tee Waveguide bends
    12. 12. COORDINATES OF CIRCULAR CAVITY RESONATOR
    13. 13. METHODS OF EXCITATION
    14. 14. WHY GOING FOR SCATTERING PARAMETERS IN CASE OF MICROWAVE NETWORKS ???
    15. 15. Waveguide Tees : a. E Plane Tee b. H Plane Tee c. Magic Tee
    16. 16. MICROWAVE HYBRID CIRCUITS • MICROWAVE JUNCTION: Interconnection of two or more devices 1.WAVE GUIDE TEES 2.DIRECTIONAL COUPLER 3.CIRCULATOR
    17. 17. MICROWAVE ISOLATOR
    18. 18. CIRCULATOR
    19. 19. Directional Coupler
    20. 20. Contrast the ideal & practicalContrast the ideal & practical directional coupler!!!directional coupler!!! idealideal - infinite directivity- infinite directivity practicalpractical directional couplerdirectional coupler 30 to 35 dB30 to 35 dB
    21. 21. TWO HOLETWO HOLE FOURFOUR HOLEHOLE SCHWINGERSCHWINGER BETHE HOLEBETHE HOLE TYPES OF DIRECTIONAL COUPLERTYPES OF DIRECTIONAL COUPLER
    22. 22. Typical Directional CouplerTypical Directional Coupler constructed Using Micro strip Lineconstructed Using Micro strip Line
    23. 23. Typical Directional CouplerTypical Directional Coupler constructed Using RECTconstructed Using RECT WAVEGUIDESWAVEGUIDES
    24. 24. MODULE 2 Microwave tubes
    25. 25. Microwave Tubes • Used for high power/high frequency combination • Tubes generate and amplify high levels of microwave power more cheaply than solid state devices • Conventional tubes can be modified for low capacitance but specialized microwave tubes are also used
    26. 26. Evolution of microwave tubes • 1935 – Heil oscillator • 1939 – klystron amplifier • 1944 – Helix type TWT • In the early 1950s – low power output of linear beam tubes to high power levels • Finally invention of Magnetrons • Several devices were developed – two significant devices among them are 1) extended interaction klystron 2) Twystron hybrid amplifier
    27. 27. SIGNAL SOURCES THAT GENERATE POWER Microwave tubes @ Frequency > 1GHz E.g.: klystron, Traveling Wave Tube, magnetron conventional vacuum tubes @ frequency < 1GHz E.g. : triodes, tetrodes, pentodes
    28. 28. What are all the constraints of ordinary vacuum tubes at frequencies beyond 1 GHz????
    29. 29. The limitations of conventional vacuum tubes at frequencies beyond 1 GHz : • Lead inductance and inter electrode capacitance effects • Transit Angle Effects • Gain-Bandwidth product limitations
    30. 30. Types of Microwave Tubes Linear beam tubes (O – Type) Crossed Field Tubes (M – Type) Eg: Klystron Reflex klystron TWT Eg: Magnetron
    31. 31. Linear beam devices Crossed field devices (I) Straight path taken by the electron beam A principle feature of such tubes is that electrons travel in a curved path (i) DC magnetic field is in parallel with DC electric field to focus the electron beam DC magnetic field is perpendicular to DC electric field
    32. 32. Types of Linear Beam Tubes TWYSTRON MULTI CAVITY KLYST TWO CAVITY KLYST LINEAR BEAM TUBES KLYSTRON TUBES HYBRID TUBES TRAVELING WAVE TUBES REFLEX KLYST LADDE- RTRON HELIX RING- BAR TWT COUPLED CAVITY TWT HELIX BWO
    33. 33. TWYSTRON • KLYSTRON + TWT = TWYSTRON • It is hybrid amplifier that uses the combinations of klystron and TWT components
    34. 34. Velocity Modulation PRINCIPLE • Electric field from microwaves at buncher alternately speeds and slows electron beam . • This causes electrons to bunch up Electron bunches at catcher induce microwaves with more energy. • The cavities form a slow-wave structure
    35. 35. Magnetron Oscillator
    36. 36. TYPES OF TRAVELING WAVE MAGNETRON • CYLINDRICAL • LINEAR • COAXIAL • VOLTAGE-TUNABLE • INVERTED COAXIAL • FREQUENCY-AGILE COAXIAL
    37. 37. 33 Narrow Pulse Magnetron SystemNarrow Pulse Magnetron System At H6 Systems Before ShippingAt H6 Systems Before Shipping
    38. 38. 2121 Narrow Pulse Magnetron SystemNarrow Pulse Magnetron System Naval Electromagnetic Radiation FacilityNaval Electromagnetic Radiation Facility
    39. 39. CHARECTRISTICS OF MAGNETRON ```` 1. EFFICIENCY η = 40 to 70% 2. POWER OUTPUT ( 800KW ) 3. OPERATING FREQUENCY ( UPTO 10GHZ )
    40. 40. MODULE 3 Microwave Devices
    41. 41. Microwave Devices • A semiconductor device for the generation or amplification of electromagnetic energy at microwave frequencies. DEFINITION…
    42. 42. Leo Esaki The Nobel Prize in Physics 1973 A NEGATIVE RESISTANCE DEVICE
    43. 43. APPLICATIONS
    44. 44. • Because of negative resistance in the forward characteristics, the device can be used actively as an oscillator • Tunnel diode symbol
    45. 45. - Ve Resistance Region VfVp Ip Vv Forward Voltage Reverse voltage Iv Reverse Current ForwardCurrent Ip:- Peak Current; Iv :- Valley Current; Vp:- Peak Voltage Vv:- Valley Voltage; Vf:- Peak Forward Voltage I V - CHARACTERISTIC OF TUNNEL DIODE p V
    46. 46. GUNN DIODE
    47. 47. • Ridley and Watkins proposed in 1961 • Hilsum calculated the transferred electron effect in III-V in 1962; experiment fails. • J.B. Gunn of IBM discovered the so-called Gunn effect in 1963 and rejected the above theory. • Kroemer explained the origin of the negative differential mobility is Ridley-Watkins-Hilsum’s mechanism
    48. 48. Avalanche Transit-time Devices ATD ’s • IMPATT Diode (IMPact Ionization Avalanche Transit Time Diode) • TRAPATT diode (Trapped plasma avalanche triggered transit-time ) • BARRITT diode (Barrier injection transit- time diode ) READ DIODE
    49. 49. READ DIODE • The basic operating principle of IMPATT diode can be understood by studying the structure proposed by READ in 1959 known as READ diode • A read diode structure , doping profile and DC electric field distribution is shown in fig
    50. 50. READ DIODE
    51. 51. MICROWAVE CAVITY FREQUENCY TUNING
    52. 52. IMPATT DIODE
    53. 53. TRAPATT DIODES
    54. 54. Voltage & current waveforms of trapatt diode
    55. 55. BARRIER-INJECTION TRANSIT-TIME DIODE BARITT
    56. 56. History  transit-time delay 에 의한 negative differential resistance 를 는 idea (Schockely ,1954)  additional phase delay 를 소개하기 위한 avalanche current 사용 (Read ,1958)  실험적으로 밝힘 (Johnston et al ,1965)  BARITT mode operation (Ruegg, Wright, 1968)  BARITT diode 를 처음으로 만듦 (coleman, Sze, 1971)
    57. 57. Structure  P-n junction, Schottky barrier, or 이 둘 의 조합으로  Doping level : 0.5~10um  Substrate 는 low series resistance 때문 에 변질됨  Series resistance 로부터 power dissipation 을 줄이기 위해서 가끔 substrate 는 10um 보다 두꺼워 짐
    58. 58. FGV
    59. 59. Characteristic  전압이 depletion edge meet 까지 가 면 , punch-through 가 일어남  Junction 이 asymmetrical 하면 , Vpt≠V‘ pt  이러한 characteristic 은 negative differential resistance or negative dV/dI 에서는 일어나지 않음
    60. 60. Characteristic  Punch-through 에서 전압  Flat-band condition 에서 전압  V1= injecting junction 을 지나는 공급된 전압의 일부  Injection current s biD s D pt qN L LqN V εε Ψ −≈ 2 2 2 s D FB LqN V ε2 2 ≈ ( ) FB FB Ibi V VV V 4 2 − =−Ψ 4 )( expexp* 1exp )( exp* 2 2 2       − −      ≈       −            Ψ+ −= FB FBbp p Ibibp pp kTV VVq kT q TA kT qV kT q TAJ φ φ
    61. 61. Characteristic  Charge Q 가 주어진 후에 , saturation velocity 로 substrate 를 돌아다님  Terminal current  Frequency L Qv I sat = L v f sat 4 3 = satv
    62. 62. Characteristic
    63. 63. Application  Microwave generator - tank circuit 에 connected, oscillator 는 dc source 로부터 microwave ac signal 로 바꿔줌 - microwave power source = burglar, proximity system  장점 – low noise level. Low voltage operation  단점 - reduced efficiency, lower output power  Voltage limiter
    64. 64. Related Device 1) Double-Velocity Transit-Time diode (DOVETT) • 유일한 특징은 saturation velocity 두 가지 값을 가진다는 것 • Heterojunction • Injection current - thermionic emission, tunneling
    65. 65. Related Device 2) Tunnel-Injection Transit-Time Diode ( TUNNETT ) • Injection current – tunneling (high field : 1MV/cm) • structure – one junction • Vicinity of injecting junction – higher doping level • n+ -layer – doping : 1019 cm-3 , thickness : 10nm • 장점 – high frequency capability (1000GHz), low voltage (2V)
    66. 66. Related Device 3) Quantum-Well-Injection Transit-Time Diode (QWITT) • Injection current – tunneling • Higher frequency (TUNNETT) • negative differential resistance Resonant tunneling mechanism
    67. 67. MODULE 4 Microwave communication
    68. 68. MODULE 4 • IT’S ALL ABOUT TWO COMMUNICATION SYSTEMS: 1. TERRESTRIAL MICROWAVE COMMUNICATION SYSTEM 2. SATELLITE MICROWAVE COMMUNICATION SYSTEM
    69. 69. 140 History of Communication Satelite • In 1964,the Intelsat Consortium was formed to operate and maintain the International Telecommunication Satellite System. • In 1965,the first commercial satellite Intelsat I (Early Bird) was launched. • In 1967-1968, it was followed by Intelsat II and Intelsat III respectively. • In 1971, it was followed by Intelsat IV. • As of 1982, there were some 400 earth stations with over 55,000 channels using the Intelsat System. 19861980 1989 1992
    70. 70. Some of the everyday Technologies that depend on radio waves: • AM and FM radio broadcasts • Cordless phones • Garage door openers • Wireless networks • Radio-controlled toys • Television broadcasts • Cell phones • GPS receivers • Ham radios • Satellite communications • Police radios • Wireless clocks
    71. 71. STRUCTURE OF ATMOSPHERE
    72. 72. Ion.. layers
    73. 73. IN IONOSPHERIC PROPAGATION • SINGLE HOP • MULTIHOP • F c = (N max)^ ½ Fc  CRITICAL FERQUENCY N max  MAXIMUM ELECTRON DENSITY
    74. 74. MODES OF PROPAGATION
    75. 75. EM SPECTRUM • Electromagnetic waves has been classified into several ranges of frequencies • Very low frequency (3 kHz to 30 kHz) • Low frequency (30 kHz to 300 kHz) • Medium frequency (300 kHz to 3000 kHz) & so on
    76. 76. • Even though the frequency range is very vast ; the propagation of these frequencies through the free space can be grouped into 3 distinct modes: 1. The ground wave propagation 2. The sky wave propagation 3. The space wave propagation
    77. 77. 1. Ground wave propagation • Radio waves below 3 MHz which includes VLF, LF & MF – propagated through the surface of the earth • This form of prop. Is “Ground wave propagation”
    78. 78. 2.Sky wave propagation • Freq.'s in the range of 3 MHz to 30 MHz – propagated through the ionosphere • The propagation of these waves are said to be “sky wave propagation”
    79. 79. 3.Space wave propagation • At the freq.’s above 30 MHz – propagated through the troposphere • These waves are called as “space waves” or “tropospheric” waves • The propagation of these waves are said to be “space wave propagation”
    80. 80. MORE ABOUT SPACE WAVE PROPAGATION.... • LOS path • Ground reflected path
    81. 81. Repeaters
    82. 82. DIVERSITY RECEPTION SCHEMES
    83. 83. (a) Frequency diversity technique
    84. 84. (b) Space diversity technique
    85. 85. (c) Polarization Diversity • A single RF carrier is propagated with two different electromagnetic polarization • This is achieved by using vertically & horizontally polarized antennas at the transmitter and receiver • The idea is that EM waves of different polarization may not experience the same transmission degradation • may be used with space diversity
    86. 86. Fig: Antenna Arrangement in space diversity reception
    87. 87. Multipath Interference
    88. 88. Fading
    89. 89. Four types of fading: 1. absorption fading 2. reflection multipath fading 3. atmospheric multipath fading and 4. sub-refraction fading
    90. 90. (b) Reflection multipath fading
    91. 91. (c) Atmospheric multipath fading
    92. 92. (d) Sub refraction fading
    93. 93. What is a Spot Beam? • A spot beam is a satellite beam which is focused on a relatively small portion of the earths surface.
    94. 94. Uplinking Antenna Satellite IMD Server,Delhi LAYOUT FOR DATABROADCAST WORLD SPACE RECEIVER DDA 128 Kbps PC PC Remote Sites INTERNET OPTION-2 World Space Server,Singapore (currently) OPTION -1 Dedicated 64Kbps link to be provided by VSNL PC Card with built-in Receiver & DDA 64Kbps Local Leased line Connectivity
    95. 95. FACTORS AFFECTING MW LINK Following major phenomenon affect MW Link • 1. REFLECTION • 2. REFRACTION • 3. DIFFRACTION • 4. SCATTERING • 5. ABSORPTION
    96. 96. Terrestrial Microwave Antennas
    97. 97. The principle of troposcatter radio communications
    98. 98. Optical and Radio Horizons
    99. 99. Fig: Effect of atmospheric refraction
    100. 100. THANK YOU

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