69 lines
3.4 KiB
Markdown
69 lines
3.4 KiB
Markdown
G9A – Feed lines: characteristic impedance and attenuation; standing wave ratio (SWR) calculation, measurement, and effects; antenna feed point matching
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- [[G9A01]] (A)
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Which of the following factors determine the characteristic impedance of a parallel conductor feed line? #card
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- A. The distance between the centers of the conductors and the radius of the conductors
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- B. The distance between the centers of the conductors and the length of the line
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- C. The radius of the conductors and the frequency of the signal
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- D. The frequency of the signal and the length of the line
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- [[G9A02]] (B)
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What is the relationship between high standing wave ratio (SWR) and transmission line loss? #card
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- A. There is no relationship between transmission line loss and SWR
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- B. High SWR increases loss in a lossy transmission line
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- C. High SWR makes it difficult to measure transmission line loss
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- D. High SWR reduces the relative effect of transmission line loss
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- [[G9A03]] (D)
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What is the nominal characteristic impedance of “window line” transmission line? #card
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- A. 50 ohms
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- B. 75 ohms
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- C. 100 ohms
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- D. 450 ohms
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- [[G9A04]] (C)
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What causes reflected power at an antenna’s feed point? #card
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- A. Operating an antenna at its resonant frequency
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- B. Using more transmitter power than the antenna can handle
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- C. A difference between feed line impedance and antenna feed point impedance
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- D. Feeding the antenna with unbalanced feed line
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- [[G9A05]] (B)
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How does the attenuation of coaxial cable change with increasing frequency? #card
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- A. Attenuation is independent of frequency
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- B. Attenuation increases
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- C. Attenuation decreases
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- D. Attenuation follows Marconi’s Law of Attenuation
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- [[G9A06]] (D)
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In what units is RF feed line loss usually expressed? #card
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- A. Ohms per 1,000 feet
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- B. Decibels per 1,000 feet
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- C. Ohms per 100 feet
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- D. Decibels per 100 feet
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- [[G9A07]] (D)
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What must be done to prevent standing waves on a feed line connected to an antenna? #card
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- A. The antenna feed point must be at DC ground potential
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- B. The feed line must be an odd number of electrical quarter wavelengths long
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- C. The feed line must be an even number of physical half wavelengths long
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- D. The antenna feed point impedance must be matched to the characteristic impedance of the feed line
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- [[G9A08]] (B)
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If the SWR on an antenna feed line is 5:1, and a matching network at the transmitter end of the feed line is adjusted to present a 1:1 SWR to the transmitter, what is the resulting SWR on the feed line? #card
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- A. 1:1
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- B. 5:1
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- C. Between 1:1 and 5:1 depending on the characteristic impedance of the line
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- D. Between 1:1 and 5:1 depending on the reflected power at the transmitter
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- [[G9A09]] (A)
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What standing wave ratio results from connecting a 50-ohm feed line to a 200-ohm resistive load? #card
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- A. 4:1
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- B. 1:4
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- C. 2:1
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- D. 1:2
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- [[G9A10]] (D)
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What standing wave ratio results from connecting a 50-ohm feed line to a 10-ohm resistive load? #card
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- A. 2:1
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- B. 1:2
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- C. 1:5
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- D. 5:1
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- [[G9A11]] (A)
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What is the effect of transmission line loss on SWR measured at the input to the line? #card
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- A. Higher loss reduces SWR measured at the input to the line
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- B. Higher loss increases SWR measured at the input to the line
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- C. Higher loss increases the accuracy of SWR measured at the input to the line
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- D. Transmission line loss does not affect the SWR measurement
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