Mumbai University Previous year question papers
V Sem Electronics Examination Dec 2007
Microwave devices and Circuits
N.S. : (1) Question NO.1 is compulsory.
(2) Attempt any four questions out of remaining six questions.
(3) Assume any suitable data whenever required but justify the same.
1. Attempt any four from the following:
(a) The TE1.omode is described as the dominant made in rectangular waveguides. What property does it have which makes it dominant?
(b) Explain the limitations of conventional vacuum tubes at microwave frequencies.
(c) Show that waveguide is nothing but HP filter.
(d) What is dispersion in optical fibers? Howdoes it affect the performance of the fiber optic link?
(e) What are crossed field devices? Explain the working principle in brief of anyone crossed field device.
2.(a) Discuss the method of excitingTE10and TE20 modesin a rectangularwaveguide.
(b) A rectangular waveguide measures 3 x 4.5 cm internally, with a 9GHz signal propogation in it find –
(i) The cut-off wavelength
(ii) The guided wavelength
(iii) The group and phase velocities.
3. (a) Withthe aid of a suitable diagram explain the operation of the hybrid T Junction. What are its applications?
(b) Explain the microwave circulator with S matrix.
(c) Define coupling factor and directivity of a directional coupler.
4. Distinguish between:
(a) IMPATTdiode and TRAPATTdiode.
(b) Step index and graded index fiber.
(c) Rectangular waveguide and circular waveguide.
(d) LASERs and LEOs. .
5.(a) Explain the process of velocity modulation and bunching in a reflex klystron oscillator with the ~elp of applegate diagram.
(b) Distinguish between spontaneous emission and stimulated emission. How stimulated emission is achieved in LASER?
6.(a) Explain Attenuation in optical fiber system.
(b) Writethe advantages and applications of optical communication system.
(c) Explain in brief, different splicing technique in optical fibers.
7. Write short notes on any four:
(a) Cavity resonator
(b) Gunn oscillator
(c) Multiplexing techniques in fiber optic system
(d) Link power budget
(e) TWT (Travelling.wave tube).