Friday 18 August 2017

Question Bank of Microwave Engineering

Chapter -1 Introduction to Microwaves:

1.      What is the importance of Microwave? Give its applications.

 Chapter -2 Microwave transmission lines and waveguides:


1.   Derive necessary equations for attenuation constant and phase constant with reference to EM wave propagating along transmission line.
2.   Draw an equivalent circuit of two wire parallel transmission line having length of Dz and derive the equations for it.
3.   What is impedance matching? Explain impedance matching using stub.
4.   Explain in brief standing wave and reflection coefficient of transmission line and derive the expression for the impedance and reflection coefficient at any point on the line.
5.   Derive the equations of characteristic and Input impedance of tow wire transmission line.
6.   Sketch circular and rectangular waveguide and compare their dominant mode, advantages and disadvantages.
7.   Difference between Strip line and Micro Strip line, with advantages and disadvantages.
8.    Explain Cutoff Wavelength of rectangular waveguide and give the relation between l0, lg, lc.
9.    Define:
1.    Group velocity.
2.    Phase velocity.
3.    VSWR.
10.Short note with Advantages and Disadvantages.
1.   Coplanar line.
2.   Slot line.
3.   l/4 and l/2  TX lines
11.              Why TE10 is the dominant mode for rectangular waveguide?
12.              Why TEM wave cannot propagate through rectangular waveguide?
13.              Draw the field pattern of TE01, TE10, TE11, TE20, TM11 for rectangular waveguide.
14.              What are the losses due to mismatch in transmission lines

Chapter – 3 Microwave component & their S-parameters :

1.      Short note on “S” parameters
2.      What do you mean by reciprocal network? Draw and explain series tee junction and find its simplified S-matrix using S-parameter.
3.      What is magic associate with magic tee junction?
4.      Explain the operation of Magic TEE with its s-parameter. Also list some applications of magic TEE. Draw and explain waveguide band, corners and twist in detail with their applications.
5.      Explain faraday’s rotation effect. Describe the construction and working of microwave isolator. Explain the terms isolation and insertion loss as related to isolator.
6.      What is the purpose of directional Coupler? Define coupling factor, directivity, isolation of Directional coupler and write expression for each.
7.      Draw schematic of four port circulator and explain its working, also show and explain how one can construct a four port circulator using two magic tees and a phase shifter.

Chapter – 4 Microwave tubes and circuits:

1.      What are the limitations of conventional tubes at high frequencies list that and explain any four.
2.      Describe the construction and working, applications and performance characteristics of a reflex klystron. Explain how velocity and current modulation takes place using the Applegate diagram.
3.      Give difference between two cavity klystron and reflex klystron. Also draw the schematic of two cavity klystron. And explain its working, performance and applications.
4.      Draw different slow wave structures and write why slow wave structures are used in traveling wave tubes? Also explain working and applications of TWT with neat sketch.
5.      Explain the mechanism of oscillations of Magnetron Oscillator with the aid of suitable diagram and discuss its performance characteristics.

 Chapter -5 Semiconductor microwave devices and circuits:

1.      Explain IMPATT Diode with its construction, working and application.
2.      Explain the Tunnel diode characteristics with the aid of Energy band diagram.
3.      Why Gun diode can’t be called a diode justifies; Explain Gunn effect using two valley theory.
4.      Give at least three differences between microwave transistor and TEDs (i.e. transfer electron devices). Write the statement of Gunn effect and explain GaAs diode.
5.      Explain figure of merit of various surface geometries of microwave bipolar transistor.
6.      Explain PIN diode and its applications.
7.      Explain construction and working of varactor diode. And also explain quality factors for same.
8.      Short note on:
A.     Parametric amplifier
B.     IMPATT and TRAPATT diode


Chapter – 6 Radar Systems:


1.      Explain the principal of RADAR. Derive the range equation of RADAR. Briefly discuss the factors which influence the range of radar.
2.      Explain advantages of RADAR. Give its applications.
3.      Short note on MTI RADAR.
4.      Explain Pulse RADAR.
5.      Explain Scanning and tracking.
6.      Short note on display of radar.
7.      What is Doppler radar? Explain CW radar and compare with FM CW radar
EXAMPLES asked in GTU Exams:
1.      The dimension of a waveguide is 2.5X1cms.The frequency is 8.6 GHz Find the possible modes that can propagate through the waveguide also find the cutoff frequencies for the same.
2.      A rectangular waveguide is filled by dielectric material of Er =9, with inside dimension of 7X3.5cm. It operates in the dominant TE10 mode. Determine (i) cut off frequency (ii) phase velocity at a frequency of 2 GHz (iii) guided wavelength at the same frequency.
3.      A typical transmission line has a resistance of 6 W /km, inductance of 2.2mH/km, a capacitance of 0.005 nF/km and a conductance of 0.05mmho/km. Calculate the characteristic impedance, attenuation constant and phase constant of the transmission line at a frequency of 1kHz.Alo calculate the phase velocity of the signal
4.      A rectangular waveguide has dimension of 2.29 cm and 1.02 cm. It is desired that this waveguide is to be operated only in dominant mode and operating frequency is at least 25% above cut off frequency of dominant mode and not higher than 95% of the next cut off frequency. What is allowable operating frequency?
5.      A 5.2 cm length of lossless 200 W line is terminated in a load impedance of 60 + j 100 W Using smith chart            
(i)                 Determine Reflection coefficient and SWR along the line.

(ii)               Determine the Z and Y at the input and at a point 2.0 cm from the load end. The signal frequency is 750 MHz and  l = l0

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