HIGHLIGHTED-Microwave-Communications.pdf

# Calculate the cutoff frequency a 35 ghz b 15 ghz c 75

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Calculate the cutoff frequency a) 3.5 GHz b) 15 GHz c) 7.5 GHz d) 4 GHz 281. The main difference between the operation of transmission liners and waveguides is that a) the latter is not distributed, like transmission lines b) the former can use stubs and quarter-wave transformers, unlike the latter c) transmission lines use the principal mode of propagation, and therefore do not suffer from low-frequency cut-off d) terms such as impedance matching and standing-wave ratio cannot be applied to waveguides 282. The useful power of the transmitter that is contained in the radiated pulses is termed as ______. a) rms power b) rated power c) peak power d) average power 283. In radars, echoes that are produced when the reflected beam is strong enough to make a second trip a) double range echoes b) double frequencies echoes c) second return echoes d) second time around echoes 284. Indicate the false statement. Compared with equivalent transmission lines, 3 GHz waveguides a) are less lossy b) can carry higher powers c) are less bulky d) have lower attenuation 285. The range beyond which targets appear as second return echoes is called a) maximum range b) maximum unambiguous range c) maximum usable range d) any of these 286. When a particular mode is excited in a waveguide, there appears an extra electric component, in the direction of propagation. The resulting mode is a) transverse electric b) transverse magnetic c) longitudinal d) transverse-electromagnetic 287. In radars, echoes that arrive after the transmission of the next pulse are called _____. a) second return echoes b) second time around echoes c) multiple time around echoes d) any of these 288. When electromagnetic waves are reflected at an angle from a wall, their wavelength along the wall is a) the same as the free space

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b) the same as the wavelength perpendicular to the wall c) shortened because of the Doppler effect d) greater than in the actual direction of propagation 289. A radar mile is equivalent to a) 2000 mi b) 2000 m c) 2000 yd d) 2000 km 290. As a result of reflections from a plane conducting wall, electromagnetic waves acquire an apparent velocity of light in space a) velocity of propagation b) normal velocity c) group velocity d) phase velocity 291. In radars, the time between pulses is called ______. a) rest time b) duration time c) delay time d) propagation time 292. Indicate the false statement. When the free- space wavelength of a signal equals the cutoff wavelength of the guide a) the group velocity of the signal becomes zero b) the phase velocity of the signal becomes infinite c) the characteristic impedance of the guide becomes infinite d) the wavelength within the waveguide becomes infinite 293. In radars, the duration of the pulse is a) duty cycle b) pulse width c) pulse amplitude d) pulse cycle 294. A signal propagated in a waveguide has a full wave electric intensity change between two further
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