HIGHLIGHTED-Microwave-Communications.pdf

A 009 b 099 c 090 d 100 266 a microwave tube

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and the average power is 18 W? a) 0.09 % b) 0.99 % c) 0.90 % d) 1.00 % 266. A microwave tube amplifier uses an axial magnetic field and a radial electric field. This is the a) reflex klystron b) coaxial magnetron c) traveling-wave magnetron
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d) CFA 267. Figure of merit used to indicate how much the signal-to-noise ratio deteriorates as a signal passes through a circuit or series of circuits a) noise factor b) signal to noise ratio c) carrier to noise ratio d) dynamic range 268. What is the peak power of a radar pulse if the pulse width is 1μs, the pulse repetition rate is 900, and the average power is 18 W? a) 10 kW b) 15 kW c) 20 kW d) 30 kW 269. The point where the antenna is mounted with respect to the parabolic reflector is called the a) focal point b) center c) locus d) tangent 270. The operating frequency of klystron and magnetrons is set by the a) cavity resonators b) DC supply voltage c) input signal frequency d) Number of cavities 271. Using a small reflector to beam waves to the larger parabolic reflector is known as a) focal feed b) horn feed c) cassegrain feed d) coax feed 272. If the noise figures and gains of each of the amplifiers in cascade is 3 dB and 10 dB respectively. What is the total noise figure? a) 2.12 dB b) 3.24 dB c) 1.24 dB d) 4.23 dB 273. One of the following is unlikely to be used as a pulsed device a) multicavity klystron b) BWO c) CFA d) TWT 274. Calculate the maximum ambiguous range for a radar system with PRT equal to 400μs. a) 13.8 mi b) 43.5 mi c) 16.4 mi d) 32.8 mi 275. When electromagnetic 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 the walls d) they travel along all four walls of the waveguide 276. What is the distance in nautical miles to a target if it takes 123 μs for a radar pulse to travel from the radar antenna to the target, back to the antenna, and be displayed on the PPI scope? a) 10 nmi b) 5 nmi c) 20 nmi d) 15 nmi 277. Waveguides are used mainly for microwave signals because a) they depend on straight-line propagation which applies to microwaves only b) losses would be too heavy at lower frequencies c) there are no generators powerful enough to excite them at lower frequencies
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d) they would be too bulky at lower frequencies 278. Calculate the coupling of a directional coupler that has 70 mW into the main guide and 0.35 mW out the secondary guide. a) 13 dB b) 23 dB c) 33 dB d) 10 dB 279. The wavelength of a wave in a waveguide a) is greater than in free space b) depends only on the waveguide dimensions and the free space wavelength c) is inversely proportional to the phase velocity d) is directly proportional to the group velocity 280. A rectangular waveguide is 1 cm by 2 cm.
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