Electronics Engineering Objective Questions { Transmission Lines and Waveguides }

Home // Electronics Engineering // Transmission Lines and Waveguides

43. For handling high powers, it is best to use

A. rectangular waveguide

C. coaxial cable

44. The cavity magnetron employs strapping in order to

A. prevent mode jumping

B. reduce frequency pushing and pulling

C. ensure bunching

D. permit better dissipation of heat

45. Indicate the FALSE statement :Frequency-agile or dither-tuned magnetron

A. has a movable piston for changing its operating frequency

B. can be easily jammed

C. may be conventional or coaxial

D. is capable of sending a series of pulses each of which is at a different frequency

46. Which statement regarding voltage tunable magnetrons (VTMs) is wrong?

A. they use high-Q cavities

B. they have an extra injection electrode to help bunching

C. their operating frequency can be varied over an octave by adjusting anode votage

D. they use cold cathodes

47. The cut-off frequency in a waveguide means

A. longer waves will not propagate significantly

B. determine the dimensions of waveguide

C. frequency at which no transmission takes place.

D. None of above

48. For a standard X-band waveguide of cross-sectional dimension 2.286 cm x 1.016 cm, the cut-off wavelength for a TEio mode is ___ cm.

49. The signal delay caused when a wave travels a distance Z metres through a hollow wave guide is where VPh' V and Vo represent phase gr velocity, group velocity and free space velocity (m/sec) respectively. given by

Page 7 of 20

« 5 6 7 89 »