Microwave & Radar Engineering - May 2013

Electronics & Telecomm. (Semester 7)

TOTAL MARKS: 80
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks. 1 (a) Differentiate between waveguide and transmission line.(5 marks) 1 (b) Explain amplification process in TWT.(5 marks) 1 (c) Compare klystron with magnetron.(5 marks) 1 (d) State and explain Lorentz Reciprocity theorem.(5 marks) 2 (a) Describe the mechanism of velocity modulation in a two cavity klystron and hence obtain an expression for the bunched beam current. Also find out condition for maximum power output.(10 marks) 2(b) Describe operation of O-type and M-type device in brief. Explain in brief Gyrotrons.(10 marks) 3 (a) Explain the working of Magic Tee. Design a circulator using Magic Tees.(10 marks) 3 (b) Explain the procedure of measurement of dielectric constant at microwave frequency.(10 marks) 4 (a) Describe construction and working of two hole directional coupler along with its S-matrix.(10 marks) 4 (b) Explain the working of a negative resistance parametric amplifier.(10 marks) 5 (a) Explain single stub matching. What are its advantages and disadvantages?(10 marks) 5 (b) Calculate the position and length of short circuited stub design to match 200 +j300 load to a transmission line whose characteristics impedance is 300 Ω (use Smith chart).(10 marks) 6 (a) Describe different modes of oscillation of Gunn diode.(10 marks) 6 (b) Explain the working of (i) Coupled line filters (ii) Filters using coupled resonators. (10 marks)

Write short notes on:

7 (a) Measurement of impedance .(5 marks) 7 (b) Hybrid junctions.(5 marks) 7 (c) Show that TM₀₁ and TM₁₀ modes in a rectangular do not exist.(5 marks) 7 (d) Microwave propagation in ferrites.(5 marks)