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ECE Objective Questions { Transmission Lines and Waveguides }

113. The reflection co-efficient on a line is 0.2 - 45?. the SWR of this line is

114. For a transmission line the, propagation constant, for a TEM wave travelling in it, is given by (where the symbols have the usual meanings)
A. [(R+ jtaL)(G +koC)]
B. [(R + jcoL) (G +koC)] ?
C. [(R - jo.)L)(G + jcoC)] ?
D. [(R - jcoL)(G + jc.o2C)] 1/3

115. A lossless, air dielectric cylindrical wave guide of inside diameter 3cm, is operated at 14GHz. For the TMii mode propagating in +z direction, the wave impedance will be (for TM iv mode, K a =3.832)
A. 120 TEO
B. 185 Q
C. 240 7cf2

116. Choose the correct statements for a wave proparating in an air filled rectangular wave guide :
A. Guided wavelength is never less than the free space wavelength
B. Wave impedance is never less than the free space impedance
C. Phase velocities is never less than the free space velocity
D. TEM mode is possible if the dimensions of the wave guide are properly chosen

117. Assuming perfect conductor of a transmission line, pure TEM propagation is NOT possible in
A. coaxial cable
B. air filled cylindical wave guide
C. parallel thin wire line in air
D. semi infinite parallel plate wave guide

118. The dominant mode in a rectangular wave guide is TE0, because this mode has
A. no attenuation
B. no cut off
C. no megnetic field component
D. the highest cut off wavelengt:;

119. When electromagetic waves are propagated in a waveguide
A. they travel along the broader walls of the guide
B. they are reflected from the walls but do not travel along them
C. they travel through the dielectric without tuuching the walls
D. they travel along all four walls of the waveguide

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