69 lines
3.0 KiB
Markdown
69 lines
3.0 KiB
Markdown
E9B Antenna patterns and designs: azimuth and elevation patterns; gain as a function of pattern; antenna modeling
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- [[E9B01]] (B)
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What is the 3 dB beamwidth of the antenna radiation pattern shown in Figure E9-1? #card
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- [[A.]] 75 degrees
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- [[B.]] 50 degrees
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- [[C.]] 25 degrees
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- [[D.]] 30 degrees
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- [[E9B02]] (D)
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What is the front-to-back ratio of the antenna radiation pattern shown in Figure E9-1? #card
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- [[A.]] 36 dB
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- [[B.]] 14 dB
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- [[C.]] 24 dB
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- [[D.]] 18 dB
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- [[E9B03]] (D)
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What is the front-to-side ratio of the antenna radiation pattern shown in Figure E9-1? #card
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- [[A.]] 12 dB
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- [[B.]] 24 dB
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- [[C.]] 18 dB
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- [[D.]] 14 dB
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- [[E9B04]] (B)
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What is the front-to-back ratio of the radiation pattern shown in Figure E9‑2? #card
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- [[A.]] 15 dB
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- [[B.]] 28 dB
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- [[C.]] 3 dB
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- [[D.]] 38 dB
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- [[E9B05]] (A)
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What type of antenna pattern is shown in Figure E9-2? #card
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- [[A.]] Elevation
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- [[B.]] Azimuth
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- [[C.]] Near field
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- [[D.]] Polarization
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- [[E9B06]] (C)
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What is the elevation angle of peak response in the antenna radiation pattern shown in Figure E9-2? #card
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- [[A.]] 45 degrees
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- [[B.]] 75 degrees
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- [[C.]] 7.5 degrees
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- [[D.]] 25 degrees
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- [[E9B07]] (C)
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What is the difference in radiated power between a lossless antenna with gain and an isotropic radiator driven by the same power? #card
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- [[A.]] The power radiated from the directional antenna is increased by the gain of the antenna
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- [[B.]] The power radiated from the directional antenna is stronger by its front-to-back ratio
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- [[C.]] They are the same
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- [[D.]] The power radiated from the isotropic radiator is 2.15 dB greater than that from the directional antenna
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- [[E9B08]] (D)
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What is the far field of an antenna? #card
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- [[A.]] The region of the ionosphere where radiated power is not refracted
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- [[B.]] The region where radiated power dissipates over a specified time period
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- [[C.]] The region where radiated field strengths are constant
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- [[D.]] The region where the shape of the radiation pattern no longer varies with distance
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- [[E9B09]] (B)
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What type of analysis is commonly used for modeling antennas? #card
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- [[A.]] Graphical analysis
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- [[B.]] Method of Moments
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- [[C.]] Mutual impedance analysis
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- [[D.]] Calculus differentiation with respect to physical properties
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- [[E9B10]] (A)
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What is the principle of a Method of Moments analysis? #card
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- [[A.]] A wire is modeled as a series of segments, each having a uniform value of current
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- [[B.]] A wire is modeled as a single sine-wave current generator
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- [[C.]] A wire is modeled as a single sine-wave voltage source
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- [[D.]] A wire is modeled as a series of segments, each having a distinct value of voltage across it
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- [[E9B11]] (C)
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What is a disadvantage of decreasing the number of wire segments in an antenna model below 10 segments per half-wavelength? #card
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- [[A.]] Ground conductivity will not be accurately modeled
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- [[B.]] The resulting design will favor radiation of harmonic energy
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- [[C.]] The computed feed point impedance may be incorrect
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- [[D.]] The antenna will become mechanically unstable
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