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ECE Objective Questions { Transmission Lines and Waveguides }

92. The main difference between the operation of transmission lines and waveguide is that
A. the latter are not distributed like transmission lines
B.the former can use stubs and quarter wave transformers, unlike the latter
C. transmission lines use the principle mode of propagation, and therefore do not suffer from low frequency cut-off
D. terms such as stub matching standing wave ratio cannot be applied to wave guides

93. The dominant mode of propagation is preferred with rectangular waveguides because (indicate false statement)
A. it leads to the smallest waveguide dimensions
B.the resulting impedance can be matched directly to coaxial lines
C. it is easier to excite than the other modes
D. propagation of it without any spurious generation can be ensured

94. A signal propagated in a waveguide hasa full wave of electric intensity change between the two further walls, and no component of the electric field in the direction of propagation, The mode is
A. TE 1, t
C. TM2,2

95. Propagation constant of a line is
A. y = 4(R + koL) (G + jwC)
B. Y = (R jo)L) (G + jco
C.(R + jo.)L)
D. none of these

96.  On a transmission line with standing waves, the distance between a voltage maximum and adjacent current maximum is
A. V8
B. V4
C. ia2
D. none of the above

97. Matching stub should be
A. nearest to load
B. nearest to transmitter
C. midway between load and transmitter
D. on transmitter

98. For transmission-line load matching over a range of frequencies, it is best to use
A. balun
B. broad band directional coupler
C. double stub
D. single stub of adjustable position.

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