JNTU BTech II Semester Examinations, MICROWAVE ENGINEERING, Apr/May 2008

JNTU B.Tech II Semester Examinations, MICROWAVE ENGINEERING, Apr/May 2008

 ( Common to Electronics & Communication Engineering and Electronics &

Telematics)

Time: 3 hours Max Marks: 80

Answer any FIVE Questions

All Questions carry equal marks

SET-IV

1. (a) Discuss the attenuation in wave guides in detail.

(b) A wave guide operating in TE10 mode has dimensions a = 2.26 cm and b = 1cm. The measured guide wave length is 4 cm. Find

i. Cut off frequency of the propagating mode

ii. The frequency of operation

iii. Maximum frequency of propagation in this mode. [8+8]

 

2. (a) Explain the concepts of propagation delay time for a strip line.

(b) Is the effective dielectric constant of a micro strip line a function of relative dielectric constant justify. [8+8]

 

3. (a) Sketch a 4 port hybrid junction and justify that it is a basically a 3 dB directional coupler.

(b) A matched generator with a power of one watt is connected to the H ? arm of magic tee C (port 4). The E arm (port 3) is match terminated and the length of the coplanar arms is the same. Compute the power delivered to the termination at port 1, 2 and 3 and the power reflected at port 4 when ports 1 and 2 are match terminated. [8+8]

 

4. What is Faraday rotation? Explain the working of a ferrite circulator with neat sketches. How can it be used as an isolator? [16]

 

5. (a) Explain in detail bunching process & obtain expression for bunching parameter

in a two cavity klystron amplifier.

(b) A reflex klystron is to be operated at a frequency of 10GHZ. With dc beam voltage 400v. Repeller spacing 0.1cm for 134 mode. Determine the maximum value of power & corresponding repeller voltage for beam current of 30mA. [8+8]

 

6. (a) Give the different types & explain the characteristics of slow wave structure.

(b) A TWT operates with following parameters:

Vb=2.5KV, Ib=25mA, Zo=10 , circuit length,L=50,f=9GHz

Find the gain parameter & power gain. [8+8]

 

7. (a) Explain the physical structure and construction of IMPATT diodes.

(b) Draw the graph between negative resistance versus transit angle and explain its Shape. [8+8]

 

8. (a) The signal power at the input of a device is 10 mw. The signal power at the

output of same device is 0.2mw. Calculate the insertion loss in db of this

component.

(b) Explain the bolometric method of measuring microwave power. [8+8]

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