B 10000EC403122001 Pages: 2

Reg No.: Name:
APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY

Seventh Semester B.Tech Degree Examination (Regular and Supplementary), December 2020

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

1 a) Explain with figure rectangular waveguide resonator. Derive the resonant (8)
frequency of rectangular cavity resonator.

b) With the help of figures explain the bunching process of an 8-cavity cylindrical (7)
magnetron.

2 a) Given the parameters of a two-cavity klystron amplifier: (8)
Beam Voltage = 1000V, Beam current = 50mA, Operating frequency = 100117,
Gap spacing=Imm, Spacing between two cavities ಎ 5cm, Ro= 40KQ, 1२, = 30KQ
Calculate
a. Input signal to generate maximum output voltage
b. Voltage gain
c. Efficiency

b) With admittance diagram explain the condition required for oscillation ina reflex (7)
Klystron.

3 a) Explain how velocity modulation changes to current density modulation in (7)
Klystron amplifier.

b) The parameters associated with a reflex klystron oscillator are: (8)
Vo =800V, 7५, =25KQ, {= 15 GHz, L =1.5 mm, e/m = 1.759 x 1011 (MKS
system). The tube is oscillating at n = 2 mode or 1 3/ 4 mode. Assume that the
transit time through the gap and beam loading can be neglected.

Determine
a) The value of the repeller voltage ५..
b) The direct current necessary to give a microwave gap voltage of 200 V.

c) The electronic efficiency under this condition.

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