## Microwaves & RADAR - Jun 2014

### Electronics & Communication (Semester 5)

TOTAL MARKS: 100

TOTAL TIME: 3 HOURS
(1) Question 1 is compulsory.

(2) Attempt any **four** from the remaining questions.

(3) Assume data wherever required.

(4) Figures to the right indicate full marks.
**1 (a)** Derive an expression for reflection coefficient and transmission coefficient in the transmission line(8 marks)
**1 (b)** Derive the relationship between SWR and reflection co-efficient.(6 marks)
**1 (c)** A telephone line has R-6 Ω/km, L=2.2 mh/km, C=0.005 μf/km and G=0.05 μ&mho/km. Determine Z_{0}, α, β and phase velocity at 1 KHz.(6 marks)
**2 (a)** Derive the field equation for TE modes in rectangular waveguide.(10 marks)
**2 (b)** A rectangular air filled copper waveguide with dimension 0.9×0.4 inch cross section and 12 inch length is operated at 9.2 GHz with a dominant mode. Find: i) Cut-off frequency; ii) Guide wavelength; iii) Phase velocity; iv) Characteristic impedance; v) The loss.(10 marks)
**3 (a)** With a neat sketch, explain the TRAPATT diode and draw its characteristics.(10 marks)
**3 (b)** Explain the parameteric amplifier with equivalent circuit. Give the advantages of parametric amplifier.(10 marks)
**4 (a)** Explain symmetrical z and y matrices for reciprocal network(6 marks)
**4 (b)** Which properties are common in s. z and y matrices?(6 marks)
**4 (c)** Derive an expression of the input reflection coefficient of a two port with mismatched load.(8 marks)
**5 (a)** Explain with a neat sketch a precision phase shift.(10 marks)
**5 (b)** With a neat sketch, explain the operation of magic tee. Also obtain the S matrix representation of the magic tee.(10 marks)
**6 (a)** Briefly explain dielectric losses, ohmic losses and radiation losses in microstrip lines.(10 marks)
**6 (b)** With a neat diagram, explain the operation of parallel strip line. Write the expression for distributed parameters, characteristic impedance and attenuation losses.(10 marks)
**7 (a)** Derive the simple radar range equation starting from the power density of isotropic antenna.(8 marks)
**7 (b)** Calculate the maximum range of a radar system which operates at 3 cm with a peak pulse power of 600kW if its minimum receivable power is 10^{3} W, the capture are of its antenna is 5m^{2} and the radar cross sectional area of the target is 20m^{2}.(5 marks)
**7 (c)** What are the applications of radar?(7 marks)
**8 (a)** Explain single delay line canceller and frequency response of the single delay line canceller.(10 marks)
**8 (b)** With neat block diagram, explain the operation of MTI Doppler signal processor.(10 marks)