Download AKTU B-Tech 6th Sem 2018-2019 REC 601 Microwave Engineering Question Paper

Download AKTU (Dr. A.P.J. Abdul Kalam Technical University (AKTU), formerly Uttar Pradesh Technical University (UPTU) B-Tech 6th Semester (Sixth Semester) 2018-2019 REC 601 Microwave Engineering Question Paper

REC601
Printed Paes:01 Sub Code: REC 601
Paperldz? Rollel | | | | | | | | | |
B TECH
(SEM?VI) THEORY EXAMINATION 2018-19
MICROWAVE ENGINEERING
T ime: 3 Hours T otal Marks: 70
Note: 1. Attempt all Sections. If require any missing data; then choose suitably.
SECTION A
1. Attempt all questions in brief. 2 x 7 = 14
a. Differentiate dominant and degenerative mode in waveguide.
b. Write any two properties of E-plane tee microwave device.
0. Define cut-off wave number (kc).show that kc 2 =m2 u s for loss less dielectric.
(1. Define insertion loss?
e. What are the applications of re?ex klystron?
f. How microwave solid state device is different from low frequency devices.
g. State the differences between TWT and klystron.
SECTION B
2. Attempt any three of the following: 7 x 3 = 21
a. Explain the working principle of IMPATT diode. How does the electric ?eld and hole
concentrations varies with the input ac signal.
b. What is electron transfer mechanism? Explain the operation and working of Gunn
diode.
c. What is directional coupler? What are the different types of directional coupler?
Explain the working principle of 2-hole directional coupler. Also determine its S-
matrix
(1. Explain the construction, working and application of microwave isolators.
What do you mean by E-plane tee and H-plane tee? Compare their propagation
characteristics.
SECTION C
3. Attempt any one part of the following: 7 x 1 = 7
(a) A TE11 mode is propagating through a circular waveguide. The guide is air ?lled and
has a diameter of 12 cm. Calculate: (Given X?11=1.841) (i) Cut off frequency (ii)
Guide wavelength for the frequency of 2.5GHz (iii) Wave impedance at 2.5 GHZ
frequency.
(b) Why is Magnetron called cross field device? What is meant by 71'. mode operation in
Magnetron containing eight cavity resonators? Describe how strapping separates the 71'.
mode from other possible modes.
4. Attempt any one part of the following: 7 x 1 = 7
(a) Explain Gunn Effect with respect to two valley model. Draw the graph between
applied electric field and current density across Gunn diode.
(b) A rectangular cavity resonator has dimension a=7.50m, b=4cm and 0:16 cm. calculate
cut? off wave number and phase constant.
5. Attempt any one part of the following: 7 x 1 = 7
(a) Classify different types of microwave ampli?ers and oscillators. Discuss
Working principle of avalanche transit time devices.
(b) What is circulator? Discuss its theory of operation and suggest its applications.
6. Attempt any one part of the following: 7 x 1 = 7
(a) With the help of functional diagram, explain the working principle of two cavity
Klystron amplifier. Calculate optimum length of drift space, maximum efficiency, and
voltage gain.
(b) What are the various methods for measuring frequency? Discuss them in details.
7. Attempt any one part of the following: 7 x 1 = 7
(a) Show that the TM01 and TMlo modes in rectangular waveguide do not exist.
(b) Discuss method to measure impedance of load. Indicate the use of smith chart in this
measurement.
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