“á û’ û ý ’ ”á” ”á “ ”

EJ – 789

*EJ789*

VI Semester B.E. (E&C) Degree Examination, January 2013 (Y2K6 Scheme) EC 603 : MICROWAVES AND RADAR Time : 3 Hours

Max. Marks : 100

Instruction : Answer five full questions choosing atleast two from each Part. PART – A 1. a) Explain in brief, the high frequency limitations of conventional tubes.

10

b) With a neat diagram, explain the construction and working of a two cavity Klystron amplifier.

10

2. a) With a neat diagram, explain the construction, working and applications of the following devices :

10

i) IMPATT diode ii) Parametric amplifier. b) Explain with a neat diagram, how tunnel diode and GUNN diode can be used as an oscillator.

10

3. With a neat diagram, explain the construction, working of Magic - Tee - Junction. Obtain the scattering matrix for a magic tee.

20

4. a) With a neat diagram, explain the construction and working of fixed type and movable type attenuator. b) Write a note on the following :

10 10

i) Fields from oscillating dipoles ii) Beam Efficiency, Directivity and Gain. P.T.O.

*EJ789*

EJ – 789 PART – B

5. a) What is an antenna array ? Derive an expression for an array factor of broadside array consisting of n-isotropic antennas. b) Plot the radiation pattern of an end five array n = 3, α =

10

π λ , d = . Also find 2 4

the directivity and beamwidth.

10

6. a) Derive the expression for radiation resistance of a loop antenna. (General Case)

10

b) Write a note on the following :

10

i) Yagi - Uda array ii) Helical - antenna. 7. a) Draw the block diagram of a MTI radar that uses a power amplifier as the transmitter. Explain the function of each block.

8

b) A radar operating at 3 GHz is radiating a power of 200 KW. Calculate the power of the reflected signal at the radar with a 20 m2 target at 5.556 Km. Given Ae = 9 m2. Also derive the necessary formula. 12 8. a) With the help of a block diagram, explain the operation of a CW Radar system. What are its applications ? 10 b) Write a note on the following : i) Pulsed Doppler radar. ii) Tracking with radar. iii) Radomes. ———————

10