QUESTION BANK
Name of the Faculty: RENUKA R KAJUR
Title of the Subject / Subject Code: MICROWAVE AND RADAR
Academic Year / Semester:2013-14
Name of the Department: ELECTRONICS AND COMMUNICATION ENGG
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UNIT-1
1. Differentiate Transmission line from wave-guides.
2. What is Smith chart? What is its application?
3. A (200+j75) Ohm load is to be matched to a 300 ohm line to give SWR=1. Calculate the
reactance of the stub and the characteristic impedance of the quarter wave transformer,
both connected to the load.
4. Calculate the length of a short-circuited line required to tune out the susceptance of a load
whose Y=(0.004-j0.002) S, placed on an air-dielectric transmission line of characteristic
admittance Y=00.0033S,at a frequency of 150 MHz
5. A load ZL=(100-j50) ohm is connected to a line whose Z0=75ohm.Calculate
a) The point nearest to the load, at which a quarter wave transformer may be inserted
to provide correct matching.
b) The ZO of the transmission line to be used for the transformer.
6. A series combination having an impedances = (450+j600) ohm at 10 MHz is connected to
a 300ohm line. Calculate the position and length of a short-circuited stub designed to
match this load to the line.
7. A quarter wave transformer is connected directly to a 50ohm load, to match this load to a
transmission line who’s Z0=75ohm.What must be the characteristic impedance of the
matching transformer?
Q24 Calculate the length of a piece of 50ohm open-circuited line if its input admittance to be
j80x10-3 S.
8. With the aid of a smith chart, calculate the position and length of a short-circuited stub
matching a (180+j120) ohm load to a 300ohm transmission line. Assuming that the load
impedance remains constant, find the SWR on the mainline when the frequency is (a)
increased by 10% (b) doubled.
9. Explain the parameters of Smith Chart.
10. Explain Double stub matching.
UNIT-4 MICROWAVE NETWORK THEORY
1. Define junction?
2. State the properties of S matrix?
3. Compare [S], [Z] and [Y] matrices?
4. Give ABCD matrix for a two port network
5. What is ABCD matrix?
6. What are the advantages of ABCD matrix?
7. Define S-matrix?
8. What is the Scattering matrix for N port device?
9. Give the S matrix of uniform transmission line
10. Give the properties of impedance [x]&admittance[y] matrix?
11. Derive the expression for S matrix representation of multi-port network (16)
12. Explain about properties of S parameters (16)
13. (a)Explain symmetrical Z and Y matrices for reciprocal network. (8)
(b)Comparison between [S],[Z] and [Y] matrices. (8)
14. Two transmission lines of characteristic impedance Z1 and Z2 are joined at plane
pp’.Express S parameter in terms of impedances.
UNIT-5 MICROWAVE PASSIVE DEVICES
1. Difference between Isolator and Circulator?
2. Give the applications of directional coupler
3. What is the principle of Microwave phase shifter?
4. What are junctions? Give some examples
5. What is Tee junction? Give two examples
6. What is the other name for magic TEE?
7. Give the S-matrix of E-plane Tee.
8. Give the S-matrix of H-plane Tee
9. Give the S-matrix of Magic Tee
10. What is hybrid ring?
11. What is the other name for Hybrid ring?
12. Name some wave guide components used to change the direction of the guide
13. What are the different types of Directional coupler?
14. What are nonreciprocal devices? Give two examples
15. Give some coupling parameters of directional coupler?
UNIT-2 WAVEGUIDES
1. Derive the S-matrices for E-plane and H-plane tee? (16)
2. Derive the S-matrices for magic tee? (16)
3. Derive the S-matrices for Directional coupler? (16)
4. (a)Explain about coaxial connector and adapter? (8)
(b)Explain the concept of waveguide corners bends and twists (8)
5. (a) Explain in detail about Attenuator? (8)
(b) Explain the concept of phase shifters? (8)
6. .Explain in detail about Isolator and Faraday rotation of Isolator? (16)
7. Explain the concept of circulator and derive the s-matrices for
Three port and four port circulator? (16)
8. A magic T is terminated at collinear ports 1 and 2 and difference port 4 by
impedances of reflection coefficients 1=0.5, 2=0.6 and 4=0.8 respectively. If 1W
power is fed at sum port 3, calculate the power reflected at port 3 and power transmitted
to other three ports. (16)
9. A three port circulator has on insertion loss of 1 db, isolation 30 db and VSWR = 1.5
find S- matrix (16)
UNIT3- MICROWAVE DIODES AND DEVICES
1. What are the applications of Tunnel Diode?
2. What are the elements that exhibit Gunn Effect?
3. What are the applications of Gunn Diode?
4. What is negative resistance?
5. What are the applications of backward diode?
6. Why is FET’s preferred to bipolar transistor at high frequencies?
7. What is the main advantage of TRAPATT over IMPATT?
8. Define GUNN EFFECT.
9. What is MESFET?
10. Explain stable amplification mode.
11. What are the factors reducing efficiency of IMPATT diode?
12. What is negative resistance in Gunn diode?
13. What are the applications of GaAs MESFET?
14. What is Transferred electron effect?
15. List the type of circuit used for IMPATT diode circuits.
16 .What is Transferred electron effect?
17. What are time parameters for TED ‘S?
18. What are the various modes of transferred electron oscillators?
19. Explain in detail about Gunn diodes and modes of operation? (16)
2. (a) Describe the conceptual view microwave diodes – crystal diodes? (8)
(b) Explain the concept of schottky diode – harmonic mixer? (8)
3. Explain in detail about PIN diodes and its applications? (16)
4. Describe the conceptual view of IMPATT diodes? (16)
5. Explain in detail about tunnel diode amplifier? (16)
6. Explain the concept of varactor diode? (16)
7. Describe the conceptual view of VCO-parametric amplifier? (16)
8. Explain in detail about microwave bipolar transistor? (16)
9. Explain the concept of microwave unipolar transistor? (16)
10. What is Transferred electron effect? Explain some of the TED’s? (16)
11. Explain the operation of TRAPATT diode?
UNIT-7 & 8 Introduction to radar & MTI & Digital Processor
Q1. How are A, B and PPI radar displays different from each other?
Q2. Calculate the maximum unambiguous range of low PRF pulse radar with a prf of 500 Hz.
Q3. Define radar resolution cell.
Q4. What do you understand by the term dwell time?
Q5. Define multiple time around echoes.
Q6. Give the function of duplexer in radar systems.
Q7. Mention the frequencies used for radar applications.
Q8. A radar is expected to have a range of 100 Km. What is the maximum allowable PRF for Unambiguous reception.
Q9. For a radar peak transmitted power is 1MW; pulse width is 1 sec and PRF is 1 KHz. Calculate
the average transmitted power.
Q10 Enlist the factors that determine the detection range of the radar.
Q11. Enlist different applications of radar.
Q12. Enlist the limitations of PPI displays.
Q13. Draw the block diagram of pulse radar system and give the function of each block.
Q14. Derive radar range equation.
RADAR DETECTION THEORY
Q1. For an antenna half power beam width is 3 and scan rate is 30 /sec .Calculate the
target illumination period. If R unamb=100 Km. Calculate the number of received
pulses every illumination period.
Q2. How are multiple time around echoes distinguished from unambiguous echoes?
Q3. What do you understand by the term false alarm?
Q4. Define radar cross section of target.
Q5. How does integration of radar pulses improve the detection capability of the radar?
Q6. In a radar receiver Pfa=1.05*10 -10BIF =1 MHz. What will be the
average false alarm time tolerable? For the same Pfa, how many dbs
above the rms voltage, the threshold voltage should be?
Q7. Explain the significance of radar cross section of targets.
Q8. Mention the operating frequency, power requirements and expected range of an
actual radar system.
Q9. The noise entering the IF amplifier is white Gaussian. If threshold to noise ratio is
14 dB, what will be the probability of false alarm?
Q10. Why do we prefer higher radar frequencies for meteorological radars?
Q11. With the help of suitable graph explain the radar cross section of a sphere.
Q12. Derive the radar range equation in terms of signal to noise ratio.
Q13. Briefly explain various types of losses taking place in radar systems.
Q14. Define integration improvement factor.
Q15. Derive surveillance radar range equation.
Q16. Consider s band pulse radar with the following parameters:
Peak transmitted power=300 kW
Pulse width=1msec
PRF=600 Hz
Antenna radius=6 ft.
Transmitted frequency=3000 MHz
Transmit loss=6 dB
Antenna efficiency=0.95
Calculate the maximum signal power at the range of 50 nautical miles.
CW AND FM RADAR
Q1. State Doppler principle of velocity determination.
Q2. Draw the block diagram of CW radar.
Q3. Draw the block diagram of FM CW radar.
Q4. Explain the principle of working of FM CW radar. How will you modify it for using as an
altimeter?
Q5. Why is multiple frequency CW radar employed? Explain its principle of operation.
Q6. With the help of block diagram explain the operation of FM CW altimeter.
Q7. Consider FM CW radar in which triangular shaped modulation is used. Draw the waveforms for
(a) Transmitted signal.
(b) Beat frequency signal
When the target is approaching radar.
Q8. How will you find out sign of radial velocity with the help of CW radar