VTU Microwaves & RADAR - December 2013 Exam Question Paper

VTU Electronics and Communication Engineering (Semester 5)
Microwaves & RADAR
December 2013

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) What are the applications of smith chart? Explain briefly.

6 M

1 (b) Define reflection co-efficient and derive the equation for reflection co-efficient.

10 M

1 (c) A transmission line has R=2Ω/m, G=0.5 m℧/m, f=1 GHz, L=8 nH/m, C=0.23 pF. Calculate i) the characteristic impedance ii) the propagation constant.

4 M

2 (a) Obtain the expression for wave impedance for TM wave propagation through a rectangular wave guide.

8 M

2 (b) An air filled circular waveguide having an inner radius of 1 cm is excited in dominant mode at 10 GHz. Find
(i) the cut off frequency of dominant mode
(ii) guide wave length
(iii) wave impedance

4 M

2 (c) Explain the construction, working and application of isolator based on Faraday rotation.

8 M

3 (a) Explain construction and operation of Gunn diode in the Gunn mode and LSA mode.

10 M

3 (b) With neat diagram, explain the construction operation of IMPATT diode and mechanism of oscillations.

10 M

4 (a) State and explain the properties of S-parameters.

8 M

4 (b) Explain S-matrix representation of multiport network.

8 M

4 (c) Write the relationship of ABCD parameters with Z-parameters.

4 M

5 (a) With a neat diagram, explain the operation of microwave attenuator.

6 M

5 (b) Explain the characteristics of a magic tee, obtain S-matrix representation.

10 M

5 (c) Explain the construction of a co-axial cable.

4 M

6 (a) Explain the construction and field patterns for microstrip line.

8 M

6 (b) Explain the different losses taking place in microstip line.

6 M

6 (c) A shield strip line has dielectric constant of the insulator ?_r=2.5k6, strip width W=25 mils, strip thickness t=14 mils, shield depth d=70 mils. Calculate (i) K factor (ii) the fringe capacitance (iii) the characteristic impedance of the line.

6 M

7 (a) Derive the simple radar range equation.

10 M

7 (b) A marine radar operating at 10 GHz has a maximum range of 50 kW and a minimum detectable single of 10^-11 W. Determine the cross-section of the target the radar can sight.

4 M

7 (c) Explain briefly the application of radars.

6 M

8 (a) With a neat block diagram, explain working principles of MTI radar.

10 M

8 (b) With a neat block diagram, explain operating of a pulse Doppler radar.

10 M

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