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IV B.Tech I Semester Supplementary Examinations, Feb/Mar - 2015

RADAR SYSTEMS

(Electronics and Communication Engineering)

Time: 3 hours Max. Marks: 75

Answer any FIVE Questions

All Questions carry equal marks

*****

1 a) What is RADAR? Explain the working principle of conventional Pulse Radar

with neat diagram? [9]

b) Radar mounted on an automobile to be used to determine the distance to a

vehicle travelling directly in front of it. The radar operates at a frequency of

9375MHz with a pulse width of 10ns. The maximum range to be 500ft. Find

PRF? If the antenna dimensions were 1ft by 1ft and the antenna efficiency were

0.6, what would be the antenna gain (dB)? [6]

2 Derive the maximum radar range equation in terms of S/N and define each

parameter. [15]

3 a) Prove that the range frequency is an average of up & down beat frequencies? [8]

b) Explain the need of Isolation between Transmitter and Receiver of a radar

system. [7]

4 a) Explain butterfly effect with suitable diagram? [8]

b) Explain the principle of Pulse Doppler radar. [7]

5 Explain about

a) Amplitude fluctuation

b) Angle fluctuation

c) Receiver & Servo Noise [15]

6 a) Explain what is a radome and necessity of Radome? [7]

b) Write short note on phased arrays. [8]

7 Derive the impulse response characteristics of a matched filter. [15]

8 What are the different types of feeds used in radar antenna? [15]

Code No: R41044 Set No. 1 R10

1 of 1

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IV B.Tech I Semester Supplementary Examinations, Feb/Mar - 2015

RADAR SYSTEMS

(Electronics and Communication Engineering)

Time : 3 hours Max. Marks: 75

Answer any FIVE Questions

All Questions carry equal marks

*****

1 a) Derive the simple radar range equation? How does the radar range vary with the

radar wavelength, everything else being the same? Explain?

[10]

b) Radar mounted on an automobile to be used to determine the distance to a

vehicle travelling directly in front of it. The radar operates at a frequency of

9375MHz with a pulse width of 10ns. The maximum range to be 500ft. Find the

average power required to detect a 10m2radar cross section vehicle at a range of

500ft, if the minimum detectable signal is 5x10-13

W.

[5]

2 a) Discuss all types of receiver noises in Radar system? [10]

b) If the noise figure of a receiver is 2.5dB, what reduction occurs in the S/N at the

output compared to the S/N at the input?

[5]

3 a) Prove that the Doppler frequency is half of difference of up & down beat

frequencies?

[8]

b) Calculate the Doppler frequency of a stationary CW Radar Transmitting at 4GHz

when a moving target approaches the radar with a radial velocity of 90 km/hour.

[7]

4 a) What is the disadvantage of blind speed occur in MTI Radar? Suggest some

techniques to minimize blind speeds?

[10]

b) What is transversal filter? Explain.

[5]

5 With neat sketch, explain the working principle of Conical-Scan tracking Radar?

[15]

6 What are the antenna parameters? Discuss in brief?

[15]

7 Explain the principle and process of correlation detection?

[15]

8 a) Explain Branch-type duplexer with a neat diagram. [7]

b) Explain how circulator can be used as duplexer for protecting a receiver circuit? [8]

Code No: R41044 Set No. 2 R10

1 of 1

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IV B.Tech I Semester Supplementary Examinations, Feb/Mar - 2015

RADAR SYSTEMS

(Electronics and Communication Engineering)

Time : 3 hours Max. Marks: 75

Answer any FIVE Questions

All Questions carry equal marks

*****

1 a) What is a Second-time-around echo? Derive the expression for maximum

unambiguous range.

[9]

b) The moon as a radar target may be described as follows: average distance to the

moon is 3.844x108m and radar cross section is 6.64x10

11m

2 and its radius is

1.738x106m.

i) What is the round-trip time (seconds) of a radar pulse to the moon and back?

ii) What should the PRF be in order to have no range ambiguities?

[6]

2 a) Derive the maximum radar range equation if N-number of pulses received at the

receiver.

[10]

b) A radar at a frequency of 1.35GHz has an antenna of width D is 32ft, a

maximum unambiguous range of 220nmi, and an antenna scan time of 10s. What

are the integration loss and integration-improvement factor when the probability

of detection is 0.9 and the probability of false alarm is 10-4

?

[5]

3 a) With neat diagram explain the working principle of a side band Super heterodyne

receiver?

[8]

b) Explain receiver bandwidth of simple CW Radar

[7]

4 What are MTI Performance limitations? Explain with suitable examples.

[15]

5 Explain about Sequential Lobing technique with a neat diagram and describe its

advantages and disadvantages.

[15]

6 Explain electronic beam steering techniques used for phased arrays.

[15]

7 Explain the working of constant false alarm rate receiver.

[15]

8 Derive the noise figure equation of N-stage cascade network. [15]

Code No: R41044 Set No. 3 R10

1 of 1

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IV B.Tech I Semester Supplementary Examinations, Feb/Mar - 2015

RADAR SYSTEMS

(Electronics and Communication Engineering)

Time: 3 hours Max. Marks: 75

Answer any FIVE Questions

All Questions carry equal marks

*****

1 a) Explain the role of Radar in remote sensing, military, airtraffic control and

navigational systems?

[12]

b) What should be the PRF of radar in order to achieve a maximum unambiguous

range of 60nmi? If the radar has a pulse width of 1.5µs, what is the extent of the

pulse energy in space in the range coordinate?

[3]

2 a) What is an integration improve factor? Derive the expression for integration loss. [10]

b) What is range ambiguity? Explain.

[5]

3 a) What are limitations of zero IF Receiver in CW radar? Explain working

principle of Non- Zero IF CW Doppler radar?

[10]

b) Calculate the Doppler frequency of a stationary CW Radar Transmitting at 1GHz

when a moving target approaches the radar with a radial velocity of 70 km/hour.

[5]

4 a) With suitable diagram, explain the working principle of Non-Coherent MTI

Radar?

[8]

b) What is the difference between MTI & Pulse Doppler radar?

[7]

5 With suitable diagram, Explain the working principle of 2- angle coordinate

amplitude comparison Mono pulse tracking radar.

[15]

6 What is the necessity of reflector in Reflector antenna? Explain the working

principle of Cassegrain antenna.

[15]

7 Derive the expression for signal-to- noise ratio of a Match filter.

[15]

8 What is a phased array antenna? Explain the various types of phased array

antenna in Radar system.

[15]

Code No: R41044 Set No. 4 R10

1 of 1

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