Microwaves & RADAR - Dec 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) Derive equations for voltage and currents for transmission line.(8 marks) 1(b) The characteristics impendance of a certain line is &neg; 10∠-16°, when frequency is Khz. At this frequency the attenuation is 0.071 NP/km phase constant is 0.35 rads/km. Calculate resistance, inductance capacitance for 1 km and also velocity of propagation.(6 marks) 1(c) Determine the input impedance of a 200Ω line, 3/8 wavelengths long terminated i 100Ω resistance, using smith chart. Also find k in magnitude and angle.(6 marks) 2(a) What are the properties of wave guide? Obtain the expression for Hz in the case of T.E. waves applying all boundary conditions.(8 marks) 2(b) The cut-off wave lengths of a rectangular waveguide was measured to be 8 cm and 4.8 cm when excited in TE₁₀ and TE₁₁ modes respectively. Determine the dimensions of the wave guide.(6 marks) 2(c) Explain the working of a four port circulator.(6 marks) 3(a) With a neat sketch expalin how PIN diode acts as a swtich. Find the expression for insertion loss.(8 marks) 3(b) Explain RWH theory in GUNN diodes and give its constructional details.(6 marks) 3(c) Calculate the operating frequency of silicon based IMPATT diode with drift length of 2μm and drift velocity of 10⁷ cm/sec.(6 marks) 4(a) Give the S-matrix representation for multiport network. Also explain the properties of S-matrix.(8 marks) 4(b) What is an H-plane Tee junction? Derive its S-matrix.(6 marks) 4(c) What are phase shifters? Explain a rotary precision phase shifter with a neat sketch.(6 marks) 5(a) Explain a magic Tee structure and its S-matrix. Also give its various applications.(8 marks) 5(b) What are micro strip lines ? Explain the field distribution with a neat sketch.(6 marks) 5(c) A micro strip line is composed of zero thickness 2.4 mm. If the line width is 1 mm and operated at 10 Ghz. Calculate Zo, the attenuation due to conductors and dielectric loss.(6 marks) 6(a) Name the various types RADAR. Derive the radar range equation.(8 marks) 6(b) A 1 kW, 3GHz radar uses single antenna with a gain of 30 dB. The receiver has noise band width of 1KHz and noise factor of 5 dB. A target of echoing area of 10 m ² at a range of 10 nautical miles is to be detected. Calculate the minimum S/N.(6 marks) 6(c) Explain block diagram of a radar with a neat diagram and explain each block.(6 marks) 7(a) Explain with a neat diagram the working of a coherent MTI radar.(8 marks) 7(b) Explain the various applications of radar.(6 marks) 7(c) Explain the need of delay line cancellers in MTI radars. Also give the characteristics of single delay line canceller.(6 marks) 8(a) Explain with a neat block diagram the working of a simple digital MTI signal processor.(7 marks) 8(b) Explain the working of a moving target detector with block diagram.(7 marks) 8(c) Explain with a neat block diagram the working of a pulse Doppler RADAR.(6 marks)