B 10000EC403122004 Pages: 2

Reg No.: Name:
APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY

Seventh Semester B.Tech Degree Regular and Supplementary Examination December 2021 (2015 Scheme)

Course Code: EC403
Course Name: MICROWAVE & RADARENGINEERING
Max. Marks: 100 Duration: 3 Hours
PARTA
Answer any two full questions, each carries 15 marks. Marks

1 a) Explain how the gap transit angle of a two-cavity klystron tube controls the (4)
coupling coefficient?

b) A rectangular cavity resonator has dimension of a=4cm, b=2cm and d=8cm. (3)
Compute the resonant frequency of an air-filled rectangular cavity operating in
the dominant mode.

c) Explain with the help of necessary diagrams how the electron bunching occurs in (8)
cylindrical magnetron?

2 a) With the help of Applegate diagram explain the bunching process in a two- (8)
cavity klystron amplifier. Derive the bunching parameter.

b) ^ reflex klystron operates under the following conditions: (7)
Vo=700V, २४ =12KQ, f= 9.3 GHz, 1.51 mm, e/m = 1.759 x 1011 (MKS
system)

The tube is oscillating at ர்‌; at the peak of the n = 2 or mode. Assume that the
transit time through the gap and beam loading to be neglected. Determine: -

1. The value of the repeller voltage Vr.

2. The direct current necessary to give a microwave gap voltage of 180 V.

3. The electronic efficiency under this condition

3 a) ^ two-cavity klystron amplifier has the following parameters: (8)

Vo =900V, Ro=120kQ, 1൦30൩൧, f=3GHz Gap spacing in either cavity is
d=Imm, spacing between the two cavities L=5cm and shunt impedance रज
=20kQ.
Determine:

1. Input gap voltage to give maximum voltage 2

2. Voltage gain neglecting the beam loading in the output cavity.

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