SUBJECT : Microwave Engineering CODE : EC 1403
BRANCH : ECE SEM : VII
DURATION : 3 Hrs MAX MARKS : 100
NOTE: ANSWER ALL QUESTIONS
SCHEME OF EVALUATION
PART – A (10 X 2 = 20)
- Why H,Yor Z parameters cannot be used at microwave frequency
Suitable equipments are not available at microwave frequencies for the measurements of voltages and current at the ports of the networks
Short circuit and open circuit conditions are difficult at these frequencies.
Active devcies like power transistors, tunnel diodes etc don’t have suability under open /short circuit conditions
- Name any four applications of microwave frequency
Long distance communications such as repeaters
aircraft altimeters
vulcanization in rubber industries
polymerization in the chemical industries
- Define Symmetry property of S-Matrix
Attenuation of wave travel from port 1 to port 2 is equal to the attenuation of wave travel from port 2 to port 1
- What is transferred electron effect
TEDs are transferred electron devices where there is a transfer of electron from a
lower valley of higher mobility to a n upper valley of lower mobility in the conduction band on application of kinetic energy greater than thermal energy but less than forbidden energy gap.
- Define the term parametric device
Producing the nonlinear effects in microwave frequency range
- Write the S matrix for Isolator
S = 0 0
1 0
7. Writs any two properties of Ferrite Devices.
i) Forward characteristics are not equal to the reverse characteristics
ii) Providing phase shift in the incoming signal
- Compare Transistor with TED
Transistor TED
1. Depends on junction property Depends on bulk property
2. Use elemental semiconductor Use compound semiconductor
3. Electrons are warm Electrons are very hot.
- What is voltage controlled mode and Current controlled mode.
Voltage controlled mode- Current can be multi valued
Current controlled mode- Voltage can be multi valued
- Define Gunn Effect
Gunn effect was first observed by GUNN in n-type GaAs bulk diodes. According to GUNN above some critical voltage corresponding to an electric field of 2000-4000 v/cm the current in every specimen became a fluctuating function of time. The frequency of oscillation was determined mainly by the specimen and not by the external circuit.
PART - B (5 X 16 = 80)
11. a) Explain the working principle of microwave isolator & write its S-matrix
Diagram - 6
Construction and working principle - 6
S matrix – 4
(OR)
b) Explain about two hole directional coupler construction & its working
principle
Performance characteristics of DC - 6
S Matrix derivation – 10
12. a) Explain E plane & H plane Tee operation with diagram.
E plane Tee operation and S matrix – 8
H plane Tee operation and S matrix – 8
(OR)
b) Explain Hybrid –ring circuit with diagram
Diagram - 6
Construction and working principle - 6
S matrix – 4
13. a) Explain the Properties of S Matrix. Also prove the Symmetry property
Zero diagonal property - 4
Symmetry property - 4
Unitary property - 4
Phase shift property – 4
(OR)
b) Explain Manley Rowe power relation & application of parametric amplifier
Diagram -4
Parametric amplifiers - 4
Parametric Up Converter - 4
Parametric Down Converter- 4
14. a) Write short notes on (1) Microwave generation (2) Microwave amplification
Microwave Amplification - 8
Microwave Generation – 8
(OR)
b) Explain the transit time limitation & power frequency limitation of microwave bipolar transistor
Due to excess of charge carriers produced there is a delay in charge carriers moving towards the other terminal of the diode. This effect is called avalanche time effect. - 4
Voltage Frequency limitation - 4
Current Frequency limitation -4
Power Frequency limitation – 4
15. a) Distinguish between transit & TEDs . Also explain the High Field Domain and Modes of Oscillation
Transit time domain mode, - 4
Quenched and delayed domain mode and - 8
LSA oscillation domain mode – 4
(OR)
b) Write short notes on i) BARITT diode
ii) TRAPATT diode
Construction – 5
Working principle - 6
Power output and Efficiency - 4
SUBJECT : Microwave Engineering CODE : EC 1403
BRANCH : ECE SEM : VII
DURATION : 3 Hrs MAX MARKS : 100
NOTE: ANSWER ALL QUESTIONS
PART – A (10 X 2 = 20)
- Mention the basic materials required for microwave integrated circuit
Substrate Material, Conductor material, Resistive, Dielctric
- List the various types of striplines used in MMIC
Strip Lines, Micro strip lines
- What are slow wave structures?
Slow wave structures are used to reduce the phase velocity of the wave traveling in waveguides.
- List the different types of Magnetrons
Negative Resistance magnetrons
Cyclotron frequency magnetron
Traveling wave magnetrons
- List the advantages of Reflex klystron over multi-cavity klystrons
Reflex klystrons can be used as an oscillator without any complex feedback circuitry as required in multi-cavity klystrons. As it is a narrow bandwidth device it can be tuned to operate at a single desired frequency in resonant circuits
- What is meant by velocity modulation?
The change in the velocity of the electrons under the influence of an alternating field is termed as velocity modulation
- What is the maximum electronic efficiency of a Reflex klystron?
22.7
8. List out the different types of losses involved in micro strip lines
Dielectric loss , Ohmic Skin Loss, Radiation Loss
- What is parallel strip line?
Two parallel plate in between conducting material
- Write the Advantages of Micro strip lines
Low cost , Less size, Low power
PART – B (5 X 16 = 80)
11. a) Explain the working principle of Reflex Klystron & derive power output & efficiency
Working principle of Reflex Klystron - 4
Derivation power output and Efficiency- 12
(OR)
b) A Reflex Klystron is operated at 5 GHz with an anode voltage 1000 V and the
cavity gap 2 mm. Calculate the gap transit angle. Find the optimum length of
the drift region. Assume N = 1¾ , VR = -500 V.
12 a) Explain the working principle of TWTA in detail
Diagram 5
Construction and working principle – 11
(OR)
b) A Reflex Klystron is operated at 9 GHz with DC beam voltage
600 V for 1¾ mode, repeller space length 1 mm, DC beam current 10 mA.
The beam coupling co-efficient is assumed to be 1. Calculate the repeller
voltage, electronic efficiency and output power.
- (a) Explain Magnetron & Derive for Hull cut off magnetic equation
Construction and working principle – 8
Derivation 8
(OR)
(b) Explain the working principle of Klystron Amplifier & derive power output & efficiency
working principle – 6
Derivation – 10
- (a) Draw the Suitable diagram and explain the Fabrication process of Monolithic Microwave integrated circuits. Give examples for Fabrication
Epitaxial Growth
Oxidation
Diffusion
Isolation
Metallization
Packing
(OR)
(b) Draw and explain Micro strip lines also derive characteristic Impedance and Q
of micro strip lines
Strip line construction derivation for Characteristic Imp - 8
Micro Strip line construction derivation for Characteristic Imp - 8
- i) Describe the four types materials used in MMIC fabrication (8)
Substrate Material, Conductor material, Resistive, Dielctric
ii) List the merits and demerits of planar transmission lines.(8)
Low cost , Less size, Low power
(OR)
(b) A micro strip line is composed of zero thickness copper conductor on a
substrate having relative dielectric constant of 8.4, dielectric loss tangent of
0.0005 and thickness of 2.4 mm.If the line width is 1 mm and operated at
10Ghz, calculate the characteristic impedance and the attenuation due to
conductor loss
SUBJECT : Microwave Engineering CODE : EC 1403
BRANCH : ECE SEM : VII
DURATION : 3 Hrs MAX MARKS : 100
NOTE: ANSWER ALL QUESTIONS
PART – A (10 X 2 = 20)
- What do you mean by coplanar strip line
Parallel conductors in between a conducting strip
- List the various types of striplines used in MMIC
Strip line, Microstrip line
- What is the formula for cyclotron angular frequency
Wo/em
- List the different types of Magnetrons
Negative Resistance magnetrons
Cyclotron frequency magnetron
Traveling wave magnetrons
- List the advantages of Reflex klystron over multi-cavity klystrons
Reflex klystrons can be used as an oscillator without any complex feedback circuitry as required in multi-cavity klystrons. As it is a narrow bandwidth device it can be tuned to operate at a single desired frequency in resonant circuits
- What is meant by velocity modulation?
The change in the velocity of the electrons under the influence of an alternating field is termed as velocity modulation
- What is the maximum electronic efficiency of a Reflex klystron?
22.7
- List out the different types of losses involved in micro strip lines
Dielectric loss , Ohmic Skin Loss, Radiation Loss
- Write the Advantages of Micro strip lines
Low cost , Less size, Low power
- Distinguish between strip line and micro strip line
Stripline - Parallel conductors in between a conducting strip
Micro stripline- in the dielectric substrate conducting strip
PART – B (5 X 16 = 80)
- (a) Derive the expression for power output and efficiency of Cylindrical magnetron
Construction and working principle – 8
Derivation 8
(OR)
(b) Explain the working principle of TWTA in detail
Diagram 5
Construction and working principle – 11
12.(a) Explain the working principle of Reflex Klystron & derive power output &
efficiency
Working principle of Reflex Klystron - 4
Derivation power output and Efficiency- 12
(OR)
(b) Explain the working principle of Klystron Amplifier & derive power output
& efficiency
Working principle of Klystron Amplifier - 4
Derivation power output and Efficiency- 12
13. (a) A Reflex Klystron is operated at 5 GHz with an anode voltage 1000 V and
the cavity gap 2 mm. Calculate the gap transit angle. Find the optimum length
of the drift region. Assume N = 1¾ , VR = -500 V.
(b) A lossless parallel strip line has a conducting strip width w. the substrate
dielectric separating the two conducting strips has a dielectric constant of 8,
a thickness d of 5mm and the characteristic impedance of 50 ohms
14. (a) Draw the Suitable diagram and explain the Fabrication process of Monolithic
Microwave integrated circuits. Give examples for Fabrication
Epitaxial Growth
Oxidation
Diffusion
Isolation
Metallization
Packing
(OR)
(b) Draw and explain Micro strip lines also derive characteristic Impedance and Q
of micro strip lines
Strip line construction derivation for Characteristic Imp - 8
Micro Strip line construction derivation for Characteristic Imp - 8
15. (a) A micro strip line is composed of zero thickness copper conductor on a
substrate having relative dielectric constant of 8.4, dielectric loss tangent of
0.0005 and thickness of 2.4 mm.If the line width is 1 mm and operated at
10Ghz, calculate the characteristic impedance and the attenuation due to
conductor loss
(OR)
(b)i) List out the basic materials required for the manufactured of MMIC
Substrate Material, Conductor material, Resistive, Dielctric
ii) Draw and explain Micro strip lines also derive characteristic Impedance and
Q of micro strip lines
Low cost , Less size, Low power
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