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

1. EC04 - 702:
MICROWAVE DEVICES AND COMMUNICATION
By
AJAL.AJ
Faculty , Dept of ECE
METS SCHOOL OF ENGINEERING,MALA

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. 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. 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. 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. 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. MODULE 1
Basics of microwave Engineering

8. Why Going For NewWhy Going For New
Wave guidingWave guiding
Structures instead ofStructures instead of
transmission linestransmission lines
??????

10. TE & TM ModesTE & TM Modes

13. Rectangular WaveguidesRectangular Waveguides
(Derivation of fields EX ,Ey ,Hx &(Derivation of fields EX ,Ey ,Hx &
Hy)Hy)

14. Waveguide components
Rectangular waveguide Waveguide to coax adapter
E-tee
Waveguide bends

15. COORDINATES OF CIRCULAR
CAVITY RESONATOR

17. METHODS OF EXCITATION

19. WHY GOING FOR
SCATTERING
PARAMETERS IN CASE OF
MICROWAVE
NETWORKS ???

22. Waveguide Tees :
a. E Plane Tee
b. H Plane Tee
c. Magic Tee

26. MICROWAVE HYBRID CIRCUITS
• MICROWAVE JUNCTION:
Interconnection of two or more devices
1.WAVE GUIDE TEES
2.DIRECTIONAL COUPLER
3.CIRCULATOR

27. MICROWAVE ISOLATOR

29. CIRCULATOR

31. Directional Coupler

32. 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

33. TWO HOLETWO HOLE
FOURFOUR
HOLEHOLE
SCHWINGERSCHWINGER BETHE HOLEBETHE HOLE
TYPES OF DIRECTIONAL COUPLERTYPES OF DIRECTIONAL COUPLER

34. Typical Directional CouplerTypical Directional Coupler
constructed Using Micro strip Lineconstructed Using Micro strip Line

35. Typical Directional CouplerTypical Directional Coupler
constructed Using RECTconstructed Using RECT
WAVEGUIDESWAVEGUIDES

36. MODULE 2
Microwave tubes

37. 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

38. 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

39. 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

40. What are all the constraints of
ordinary vacuum tubes at
frequencies beyond 1 GHz????

41. 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

42. Types of Microwave Tubes
Linear beam tubes
(O – Type)
Crossed Field Tubes
(M – Type)
Eg:
Klystron
Reflex klystron
TWT
Eg:
Magnetron

43. 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

44. 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

45. TWYSTRON
• KLYSTRON + TWT = TWYSTRON
• It is hybrid amplifier that uses the
combinations of klystron and TWT
components

48. 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

52. Magnetron Oscillator

54. TYPES OF TRAVELING WAVE
MAGNETRON
• CYLINDRICAL
• LINEAR
• COAXIAL
• VOLTAGE-TUNABLE
• INVERTED COAXIAL
• FREQUENCY-AGILE COAXIAL

55. 33
Narrow Pulse Magnetron SystemNarrow Pulse Magnetron System
At H6 Systems Before ShippingAt H6 Systems Before Shipping

56. 2121
Narrow Pulse Magnetron SystemNarrow Pulse Magnetron System
Naval Electromagnetic Radiation FacilityNaval Electromagnetic Radiation Facility

57. CHARECTRISTICS OF
MAGNETRON ````
1. EFFICIENCY η = 40 to 70%
2. POWER OUTPUT ( 800KW )
3. OPERATING FREQUENCY
( UPTO 10GHZ )

58. MODULE 3
Microwave Devices

59. Microwave Devices
• A semiconductor device for the generation
or amplification of electromagnetic energy
at microwave frequencies.
DEFINITION…

98. Leo Esaki
The Nobel
Prize in
Physics 1973
A NEGATIVE RESISTANCE DEVICE

105. APPLICATIONS

106. • Because of negative resistance in the
forward characteristics, the device can
be used actively as an oscillator
• Tunnel diode symbol

107. - 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

108. GUNN DIODE

109. • 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

115. 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

116. 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

117. READ DIODE

118. MICROWAVE CAVITY
FREQUENCY TUNING

119. IMPATT DIODE

123. TRAPATT DIODES

124. Voltage &
current
waveforms
of trapatt
diode

125. BARRIER-INJECTION TRANSIT-TIME DIODE
BARITT

126. 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)

127. 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

129. FGV

130. 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

131. 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

132. 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

133. Characteristic

134. 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

135. Related Device
1) Double-Velocity Transit-Time diode
(DOVETT)
• 유일한 특징은 saturation velocity
두 가지 값을 가진다는 것
• Heterojunction
• Injection current
- thermionic emission, tunneling

136. 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)

137. Related Device
3) Quantum-Well-Injection Transit-Time Diode
(QWITT)
• Injection current – tunneling
• Higher frequency (TUNNETT)
• negative differential resistance
Resonant tunneling mechanism

138. MODULE 4
Microwave communication

139. MODULE 4
• IT’S ALL ABOUT TWO
COMMUNICATION SYSTEMS:
1. TERRESTRIAL MICROWAVE
COMMUNICATION SYSTEM
2. SATELLITE MICROWAVE
COMMUNICATION SYSTEM

140. 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

141. 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

142. STRUCTURE OF ATMOSPHERE

143. Ion.. layers

146. IN IONOSPHERIC PROPAGATION
• SINGLE HOP
• MULTIHOP
• F c = (N max)^ ½
Fc  CRITICAL FERQUENCY
N max  MAXIMUM ELECTRON DENSITY

147. MODES OF PROPAGATION

148. 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

149. • 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

150. 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”

151. 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”

152. 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”

153. MORE ABOUT SPACE WAVE
PROPAGATION....
• LOS path
• Ground reflected path

154. Repeaters

155. DIVERSITY RECEPTION SCHEMES

156. (a) Frequency diversity technique

157. (b) Space diversity technique

158. (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

159. Fig: Antenna Arrangement in space
diversity reception

160. Multipath Interference

161. Fading

162. Four types of fading:
1. absorption fading
2. reflection multipath fading
3. atmospheric multipath fading and
4. sub-refraction fading

163. (b) Reflection multipath fading

164. (c)
Atmospheric multipath fading

165. (d) Sub refraction fading

166. What is a Spot Beam?
• A spot beam is a satellite beam which is
focused on a relatively small portion of the
earths surface.

167. 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

169. FACTORS AFFECTING MW
LINK
Following major phenomenon affect MW
Link
• 1. REFLECTION
• 2. REFRACTION
• 3. DIFFRACTION
• 4. SCATTERING
• 5. ABSORPTION

170. Terrestrial Microwave Antennas

174. The principle of troposcatter
radio communications

175. Optical and Radio Horizons

176. Fig: Effect of atmospheric
refraction

181. THANK YOU