Microwave And Radar Model Question Paper-Dec/2010

Fifth Semester B.E Degree Examination, Dec/10/Jan-11

Model Set-1

On

Microwave and Radar

1    a. Define and derive Expression for reflection coefficient and transmission coefficient for a transmission line.                                       (8 Marks)

b. What is Standing wave ratio? Derive the expression for propagation constant.

                                                                                                (8 Marks)

c. A transmission line has the following parameters:

    R=4KΩ/m,      G=1 mho/m,        f=1.5 GHz,         C=0.5pF

    Calculate i) the characteristics impedence   ii) the propagation constant.  (4 )

2        a. derive the relevant equation for the propagation of TE waves in a rectangular                         waveguide and explain how the dominant mode is obtained?     (12 Marks)

b. Explain the single stub matching. State the important expressions related to it.

                                                                                                (4 Marks)

c. The cutoff wavelength of a rectangular waveguide was measured to be 8cm and 4.8 cm when excited in TE₁₀ and TE₁₁ modes respectively. Determine the dimension of the waveguide.                                                      (4 Marks)

     3     a. Explain with relevant figure the fundamental of RWH theory.     (5 Marks)

b. Explain with diagram IMPATT diode.                                           (8 Marks)

c. An IMPATT diode has the following parameters

            diode junction resistance= R_j=-2Ω

            junction capacitance =Cj=0.2pF

            Breakdown voltage= V_bd= 80volts

            Package lead inductance= L_p= 0.88nH

            Package capacitance= Cp= 0.3pF

Bias current= 80mA

             Determine:     (a) the exact resonant frequency

                                    (b) the average output power

                                    (c) the average input power

                                    (d) the efficiency.

4      a. Explain the relation between incident and reflected waves in terms of scattering    parameters for a two port network. Also explain physical significance of s-parameters.                                                                                         (8 Marks)

            b. List properties of s-matrix.                                                              (12 Marks)

5            a. Explain with neat sketches the construction and operation of a H-plane Tee junction. List the characteristics and hence derive the s-matrix of a H-plane Tee junction.

(10 marks)

            b. Discuss applications of Magic Tee.                                     (5 Marks)

            c. Consider a lossless h-plane Tee junction with 50mW of power being fed into port(1) and the other two ports(2) and (3) are terminated in matched termination. Calculate the power fed into each of the ports by the junction.                      (5 Marks)

     6      a. What are the losses in microstrip lines? Exolain in detail. (10 marks)

b. Write down the advantages and disadvantages of Plannar transmission lines over co-axial lines.                                                                                    (4 Marks)

            c. Calculate the characteristics impedance Zo of a microscope line given that the   thickness of the quartz substrate is 150 microns, thickness of strip is 50 microns and the width of the strip is 275 microns. The dielectric constant of quartz is given to be 3.8.

   7       a. Derive the expression for radar range equation.                             (6 Marks)

            b. Discuss the effect of each parameter on the maximum detection range of Radar. And list the application of Radar.                                                             (8 Marks)

            c. A Radar transmitter operates at 12 GHz and transmits 400 KW of peak pulse power. If the antenna has a gain of 36 dB and the power received from a target at 80 Km is 4x10^-10 watts, what is the radar cross section of the target.              (6 marks)

    8      a. Explain the Doppler frequency shift in a moving target.                (6 marks)

            b. Briefly explain the following  with reference to Radar.

                        i) Blind speed

                        ii) MTI improvement Factor

                  iii) Delay line cancellor.  

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