Microwave & Radar Engineering - December 2014

MU Electronics and Telecom Engineering (Semester 7)

Total marks: --
Total time: -- INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary 1 (a) Microstrip line is also called an open strip line. Comment on this. 5 marks

1 (b) What do you understand by the terms cutoff wavelength, dominant mode, guide wavelengths, phase velocity and wave impedance. 5 marks

1 (c) Explain the action of a rat-race junction. 5 marks

1 (d) Discuss the power frequency, current frequency and power gain frequency limitations with reference to a microwave transistor. 5 marks

2 (a) What is the importance of beam-coupling coefficient. Derive line equation of velocity modulation in klystron. 5 marks

2 (b) A refler klystron operster at 8 Ghz at the peak of n=2 mode with V_o=300V R_sn=20kΩ and L=1mm. If the gap transit time and beam loading are neglected, find the (a) Repeller voltage (b) Beam current necessary to obtain an RF gap voltage of 200V. 5 marks

3 (a) Discuss design procedure for filter using insertion loss method. Compare this with image-paramter method. 5 marks

3 (b) Explain the procedure of measurement of dielectric constant at microwave frequency. 5 marks

4 (a) Describe different modes of oscillation of gun-diode. Differentiate between transferred electron devices and transistors. 5 marks

4 (b) How is bunching activated in a cavity magnetron. Explain phase focusing effect. What is strapping in magnetron. 5 marks

5 (a) Describe in detail the operation of a 2-hole directional coupler. Calculate the coupling factor if the power in the primary waveguide is 72 mw and the power delivered to the directional coupler is 8 mw. 5 marks

5 (b) A single stubtuner is to match lossless line of 400? to a local of 800-j300?. The frequency is 3GHz.
i) Find the distance in meters from load to a tuning stub.
ii) Determine the length in meter of the short circuited stub. 5 marks

6 (a) Explain the working of a negative resistance Parametric amplifier and explain its application. 5 marks

6 (b) Derive plane wave equation and explain the significance. 5 marks

7 (a) Explain Traveling wave to be as an amplifier. 5 marks

7 (b) Explain Hybrid junction. 5 marks

7 (c) Explain Brillouin flow and derive an expression for Brillouin magnetic field Br. 5 marks

7 (d) Design a circulator using Magic-T. 5 marks