Microwaves & RADAR - May 2016

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) Starting from fundamental, derive the expression for the voltage and current at any point on the transmission line.(8 marks) 1(b) A transmission line has the following primary constants R = 10.4 Ω/km, L = 0.00367 H/km, G = 0.8 × 10^-6 ℧/km , C = 0.000835 μF/km. Find α, β, γ, λ and z₀.(6 marks) 1(c) Define and derive expression for reflection coeficient and transmission coefficient for a transmission line.(6 marks) 2(a) A load of Z_R = 115 - j75Ω terminates at a lossless 100Ω line.Use Smith chart to determine: (i) SWR, (ii) I/P impedance of a 0.2λ long line, (iii) the distance from load to first voltage maximum.(8 marks) 2(b) With neat diagram, explain Faraday's rotation isolator.(5 marks) 2(c) With diagram, explain working of two hole direction coupler and also derive s-matrix for the same.(7 marks) 3(a) Explain with a neat diagram the construction and working of PIN diode and Schottkey barrier diode.(10 marks) 3(b) An M-Si-M BARITT diode has the following parameter:
i) Relative dielectric constant of silicon ε_r = 118.
ii) Donor concentration, N = 2.8 × 10²¹/m³
iii) Silicon length, L = 6μm
Determine the breakdown voltage and the breakdown electric field.(5 marks) 3(c) What is Gunn effect? Explain with constructional details of a Gunn diode.(5 marks) 4(a) Derive the following losses in a microwave network in terms of S-parameter:
i) Insertion loss
ii) Transmission loss
iii) Reflection loss
iv) Return loss(6 marks) 4(b) State and explain properties of S-parameters.(6 marks) 4(c) Two transmission lines of characteristics impedance z₁ and z₂ are joined at plane pp¹. Express s-parameter in terms of impedance.(8 marks) 5(a) With neat diagram, explain the working of rotary precision phase shifter.(10 marks) 5(b) Explain H-plane Tee junction and derive the S-matrix also.(6 marks) 5(c) A 20 MW signal is fed into one of collinear port 1 of a lossless H-plane T-junction. Calculate power delivered through each port when other ports are terminated in matches load.(4 marks) 6(a) Explain the various losses taking place in microstriplines.(7 marks) 6(b) Explain the construction and field pattern for microstripline.(8 marks) 6(c) Compare stripline and microstripline.(5 marks) 7(a) Derive Radar range equationo in terms of effective aperture, radar cross section of target and minimum detectable signal power of receivers.(8 marks) 7(b) Discuss various application of Radar.(6 marks) 7(c) With respect to Radar system explain:
Mximum unambiguous Range
ii) Clutter attenuation
iii) Improvement factor
iv) Doppler shift(6 marks) 8(a) Explain MTI Radar with neat block diagram.(10 marks)

Write short notes on any two:

8(b)(i) Delay line canceller(5 marks) 8(b)(ii) C.W. Doppler Radar(5 marks) 8(b)(iii) Pulsed Radar(5 marks) 8(b)(iv) Blind speed(5 marks)