SRM University 2007 B.Tech Electronics and Communications Engineering BANK FOR Transmission Lines and Wave Guides - Question Paper

iii. Distance ranging from the load and 1st voltage minimum

5. Determine the length and location of the stub to produce an impedance match on a line of Ro = 600ohms terminated in 200 ? 0o ohms. The stub is short circuited at the other end. Verify outcome using Smith chart.

6. A transmission line 52 cm long has a characteristic impedance of 50 ohms. It is terminated in a load of ZR. The VSWR is 2.5. The 1st voltage minima occur at 18cm and second voltage minima 38cm from the load end. Using smith chart, determine ZR and input impedance of the line.


7. An R.F. transmission line with a characteristic impedance of 300? 0o is terminated in an impedance of 100 ?45o ohms. This load is to be matched to the transmission line by using a short circuited stub. With the help of a Smith chart determine the length of the stub and its distance from the load.

8. A transmission line has a characteristics impedance of 300 ? and terminated in a load 150 +j150? . obtain the subsequent using Smith Chart. a) VSWR b) Reflection coefficient
c) Impedance at a distance of 0.1? from the load. d) Position of 1st voltage minimum from the load.

9. For a load 25 + j50 design a double stub tuner making the distance ranging from stubs ?/8. The distance ranging from the first stub and load is ?/4. presume Z0=50?

UNIT – IV GUIDED WAVES AND WAVEGUIDES
PART-A

1. Distinguish ranging from transverse electric and transverse magnetic waves
2. Distinguish ranging from phase velocity and group velocity
3. Give the expression for cut-off frequency for TE Mode.
4. What is the cut-off wavelength for the TE10 mode?
5. Define Guide Wavelength.
6. What is phase velocity?
7. Why is the dominant mode of propagation preferred with rectangular Wave Guide.?
8. State any 2 characteristics of TEM waves.
9. What is a waveguide?
10. What are the transverse electric (TE) Waves?
11. What are the transverse magnetic (TM) Waves?
12. Find the frequency of minimum attenuation for TM mode.
13. Define dominant mode in a Wave Guide.
14. Write down the relation ranging from guide wavelength, free space wavelength and Cut-off wavelength.
15. For the TM mode ranging from parallel planes, Write down an expression for the frequency at which the attenuation is a minimum.
16. Mention the advantages and disadvantages of circular Wave Guide.
PART-B

1. A 4GHZ signal is propagated in a rectangular Wave Guide with internal dimensions of five X 2.5 cm. Assuming the dominant mode, compute.
a) Cut-off wavelength b) Guide Wavelength
c) Group Velocity d) Phase Velocity
2. Obtain the field components of the wave propagating ranging from parallel planes.
3. Derive the EM field expression for TM Waves guided by a parallel plane perfectly conducting structure.
4. Derive the field expressions for TE Waves guided by a parallel plane perfectly conducting structure.
5. Deduce expression for propagation Constant, Wavelength and Velocity of propagation for TE waves ranging from parallel planes.
6. Discuss the propagation of TM waves in a rectangular Wave Guide. Derive the general relationship which connects free space wavelength, guide wavelength and critical wavelength.
7. An air filled hollow rectangular Wave Guide has cross-sectional dimensions 12cm X 9cm. obtain the cut off frequency for the subsequent modes:
i)TE10, TE11, and TE21.
ii) discuss why it is not possible to propagate a TEM wave inside a hollow Wave Guide of any cross section?

UNIT – V WAVEGUIDE TECHNOLOGY
PART-A

1. Differentiate ranging from Transmission Lines and Wave Guides.
2. What is the need for coupling in waveguides?
3. Why is slot given in Wave Guide?
4. What is directional Coupler?
5. How do you suppress the unwanted modes?
6. What is the purpose of resonant obstacles in Wave Guides.?
7. State the function of directional Coupler?
8. What are called unwanted modes in a Wave Guide?
9. Mention 2 applications of Wave Guide directional Couplers?
10. What is the purpose of mode filter?
PART-B

1. Explain in detail, the generation of various Wave Guide modes.
(a)Describe the various modes of impedance matching in Wave Guides.
(b)How do you suppress the unwanted modes? discuss.

2. Write a short notes on
a) Directional Coupler b) Resonant Obstacles in Wave Guide

3. Discuss in detail the field distributions and SWR in waveguide
4. Explain the subsequent
i) Coupling and leakage through slots and holes in Wave Guide walls.
ii) Reflected and Incident Waves and SWR in Wave Guide.

Earning:   Approval pending.