HIGHLIGHTED-Microwave-Communications.pdf

For proper operation a magnetron must be accompanied

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92. For proper operation, a magnetron must be accompanied by a A. Cavity resonator B. Strong electric field C. Permanent magnet D. High dc voltage 93. The operating frequency of klystrons and magnetrons is set by the
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A. Cavity resonators B. DC supply voltage C. Input signal frequency D. Number of cavities 94. A magnetron is used only as a/an A. Amplifier B. Oscillator C. Mixer D. Frequency multiplier 95. A common application for magnetron is in A. Radar B. Satellites C. Two-way radio D. TV sets 96. In a TWT, the electron beam is density- modulated by a A. Permanent magnet B. Modulation transformer C. Helix D. Cavity resonator 97. The main advantage of a TWT over a klystron for microwave amplification is A. Lower cost B. Smaller size C. Higher power D. Wider bandwidth 98. High-power TWTs are replacing what in microwave amplifiers? A. MESFETs B. Magnetrons C. Klystrons D. IMPATT diodes 99. The most widely used microwave antenna A. Half-wave dipole B. Parabolic C. Hyperbolic D. Horn 100. ______________ is a measure of reliability expressed as the average number of hours between successive failures. A. MTBF B. MTTR C. Downtime D. Outage time 101. The free space attenuation between two microwave antennas 40 km apart operating at 8 GHz is A. 146.7 dB B. 142.55 dB C. 82.5 dB D. 86.7 dB 102. An active microwave radio repeater that can provide drops and inserts. A. Broadband repeater B. Baseband repeater C. IF repeater D. RF repeater 103. If the correction factor k equals 4/3 of the earth’s curvature, the microwave beam woul d have a curvature that is ___________ than that of the earth. A. More B. Less C. Equal D. Not related 104. The optimum clearance from an obstacle in an microwave system is accepted as __________ of the first fresnel zone radius. A. 0.6 B. 0.5 C. 0.9 D. 1.5 105. The microwave beam curves the same than that of the earth when the value of the correction factor k equals A. 0
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B. 4/3 C. 2/3 D. Infinity 106. The time from the transmission of a radar pulse to its reception is 0.12 ms. The distance to the target is how many nautical miles? A. 4.85 nmi B. 9.7 nmi C. 11.2 nmi D. 18.4 nmi 107. The ability of a radar to determine the bearing to a target depends upon the A. Antenna directivity B. Speed of light C. Speed of the target D. Frequency of the signal 108. The pulse duration of a radar signal is 699ns. The PRF is 185 pulses per second. The duty cycle is A. 0.216 % B. 0.130 % C. 0.013 % D. 0.407 % 109. The Doppler effect allows which characteristics of a target to be measured? A. Distance B. Azimuth C. Altitude D. Speed 110. The Doppler effect is a change in what signal characteristics produced by relative motion between the radar set and a target?
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