Deemed University 2009 A.M.I.E.T.E Electronics

c. In a microwave power measurement set up, the avg. Pulse power is 250 W and duration of pulse is five sec. If the time interval ranging from the pulses is measured as two m sec, determine the value of peak pulse power. (4)

Q.5 a. describe a re-entrant cavity and provide at lowest 2 examples. Where are these used? (6)

b. A lossless parallel strip line has a conducting strip width w. The substrate dielectric separating the 2 conducting strips has a relative dielectric constant of six (BeO) and thickness d of four mm. compute
(i) The needed width w of the conducting strip in order to have characteristic impedance of 50.
(ii) The strip line capacitance.
(iii) The strip line inductance.
(iv) The phase velocity of the wave in the parallel strip line. (10)

Q.6 a. discuss the construction and working of directional coupler. Derive expression for coupling factor and directivity. Compare single hole and double hole directional coupler. (6)

b. What is Magic Tee? Why is it called so? discuss the characteristics of the Tee considering different input/output conditions. (6)

c. What is circulator? define construction and working of a 4 port Faraday rotation circulator. (4)

Q.7 a. elaborate degenerate modes? discuss with illustration that degenerate modes do not have identical field trend. (4)

b. What is a micro strip line? How does its characteristic impedance change with change in width to height ratio? provide a cause for using lower dielectric constant substrate in place of alumina at higher microwave frequencies. (6)

c. A rectangular cavity resonates in the mode at five GHz. provided a = 8.0 cm and b = 6.0 cm, compute the resonant frequencies for and modes. presume cavity is air filled. (6)

Q.8 a. elaborate microwaves? Enumerate the basic advantages and a few typical applications of microwaves. (4)

b. Draw the schematic diagram of TWT amplifier and define its principle of operation. provide the propagation characteristics of various waves generated in the amplifier. discuss how r.f. power output and gain vary with the change in r.f. power input. (12)




Q.9 a. discuss the basic principles of a radar system. provide the limitation and application of radars. (8)

b. discuss the following:

(i) CW Doppler Radar.
(ii) FMCW Doppler Radar. (8)

Earning:   Approval pending.