Initial checkin
This commit is contained in:
Chris
85
logseq/bak/pages/E9D/2025-05-01T20_36_29.901Z.Desktop.md
Normal file
85
logseq/bak/pages/E9D/2025-05-01T20_36_29.901Z.Desktop.md
Normal file
@ -0,0 +1,85 @@
|
||||
E9D Yagi antennas; parabolic reflectors; feed point impedance and loading of electrically short antennas; antenna Q; RF grounding
|
||||
|
||||
- [[E9D01]] (D)
|
||||
How much does the gain of an ideal parabolic reflector antenna increase when the operating frequency is doubled?
|
||||
- [[A.]] 2 dB
|
||||
- [[B.]] 3 dB
|
||||
- [[C.]] 4 dB
|
||||
- [[D.]] 6 dB
|
||||
--
|
||||
- [[E9D02]] (C)
|
||||
How can two linearly polarized Yagi antennas be used to produce circular polarization?
|
||||
- [[A.]] Stack two Yagis to form an array with the respective elements in parallel planes fed 90 degrees out of phase
|
||||
- [[B.]] Stack two Yagis to form an array with the respective elements in parallel planes fed in phase
|
||||
- [[C.]] Arrange two Yagis on the same axis and perpendicular to each other with the driven elements at the same point on the boom and fed 90 degrees out of phase
|
||||
- [[D.]] Arrange two Yagis collinear to each other with the driven elements fed 180 degrees out of phase
|
||||
--
|
||||
- [[E9D03]] (A)
|
||||
What is the most efficient location for a loading coil on an electrically short whip?
|
||||
- [[A.]] Near the center of the vertical radiator
|
||||
- [[B.]] As low as possible on the vertical radiator
|
||||
- [[C.]] At a voltage maximum
|
||||
- [[D.]] At a voltage null
|
||||
--
|
||||
- [[E9D04]] (C)
|
||||
Why should antenna loading coils have a high ratio of reactance to resistance?
|
||||
- [[A.]] To swamp out harmonics
|
||||
- [[B.]] To lower the radiation angle
|
||||
- [[C.]] To maximize efficiency
|
||||
- [[D.]] To minimize the Q
|
||||
--
|
||||
- [[E9D05]] (D)
|
||||
Approximately how long is a Yagi’s driven element?
|
||||
- [[A.]] 234 divided by frequency in MHz
|
||||
- [[B.]] 1005 divided by frequency in MHz
|
||||
- [[C.]] 1/4 wavelength
|
||||
- [[D.]] 1/2 wavelength
|
||||
--
|
||||
- [[E9D06]] (B)
|
||||
What happens to SWR bandwidth when one or more loading coils are used to resonate an electrically short antenna?
|
||||
- [[A.]] It is increased
|
||||
- [[B.]] It is decreased
|
||||
- [[C.]] It is unchanged if the loading coil is located at the feed point
|
||||
- [[D.]] It is unchanged if the loading coil is located at a voltage maximum point
|
||||
--
|
||||
- [[E9D07]] (D)
|
||||
What is an advantage of top loading an electrically short HF vertical antenna?
|
||||
- [[A.]] Lower Q
|
||||
- [[B.]] Greater structural strength
|
||||
- [[C.]] Higher losses
|
||||
- [[D.]] Improved radiation efficiency
|
||||
--
|
||||
- [[E9D08]] (B)
|
||||
What happens as the Q of an antenna increases?
|
||||
- [[A.]] SWR bandwidth increases
|
||||
- [[B.]] SWR bandwidth decreases
|
||||
- [[C.]] Gain is reduced
|
||||
- [[D.]] More common-mode current is present on the feed line
|
||||
--
|
||||
- [[E9D09]] (D)
|
||||
What is the function of a loading coil in an electrically short antenna?
|
||||
- [[A.]] To increase the SWR bandwidth by increasing net reactance
|
||||
- [[B.]] To lower the losses
|
||||
- [[C.]] To lower the Q
|
||||
- [[D.]] To resonate the antenna by cancelling the capacitive reactance
|
||||
--
|
||||
- [[E9D10]] (B)
|
||||
How does radiation resistance of a base-fed whip antenna change below its resonant frequency?
|
||||
- [[A.]] Radiation resistance increases
|
||||
- [[B.]] Radiation resistance decreases
|
||||
- [[C.]] Radiation resistance becomes imaginary
|
||||
- [[D.]] Radiation resistance does not depend on frequency
|
||||
--
|
||||
- [[E9D11]] (D)
|
||||
Why do most two-element Yagis with normal spacing have a reflector instead of a director?
|
||||
- [[A.]] Lower SWR
|
||||
- [[B.]] Higher receiving directivity factor
|
||||
- [[C.]] Greater front-to-side
|
||||
- [[D.]] Higher gain
|
||||
--
|
||||
- [[E9D12]] (C)
|
||||
What is the purpose of making a Yagi’s parasitic elements either longer or shorter than resonance?
|
||||
- [[A.]] Wind torque cancellation
|
||||
- [[B.]] Mechanical balance
|
||||
- [[C.]] Control of phase shift
|
||||
- [[D.]] Minimize losses
|
||||
85
logseq/bak/pages/E9D/2025-05-01T20_36_51.632Z.Desktop.md
Normal file
85
logseq/bak/pages/E9D/2025-05-01T20_36_51.632Z.Desktop.md
Normal file
@ -0,0 +1,85 @@
|
||||
E9D Yagi antennas; parabolic reflectors; feed point impedance and loading of electrically short antennas; antenna Q; RF grounding
|
||||
|
||||
- [[E9D01]] (D)
|
||||
How much does the gain of an ideal parabolic reflector antenna increase when the operating frequency is doubled? #card
|
||||
- [[A.]] 2 dB
|
||||
- [[B.]] 3 dB
|
||||
- [[C.]] 4 dB
|
||||
- [[D.]] 6 dB
|
||||
--
|
||||
- [[E9D02]] (C)
|
||||
How can two linearly polarized Yagi antennas be used to produce circular polarization? #card
|
||||
- [[A.]] Stack two Yagis to form an array with the respective elements in parallel planes fed 90 degrees out of phase
|
||||
- [[B.]] Stack two Yagis to form an array with the respective elements in parallel planes fed in phase
|
||||
- [[C.]] Arrange two Yagis on the same axis and perpendicular to each other with the driven elements at the same point on the boom and fed 90 degrees out of phase
|
||||
- [[D.]] Arrange two Yagis collinear to each other with the driven elements fed 180 degrees out of phase
|
||||
--
|
||||
- [[E9D03]] (A)
|
||||
What is the most efficient location for a loading coil on an electrically short whip? #card
|
||||
- [[A.]] Near the center of the vertical radiator
|
||||
- [[B.]] As low as possible on the vertical radiator
|
||||
- [[C.]] At a voltage maximum
|
||||
- [[D.]] At a voltage null
|
||||
--
|
||||
- [[E9D04]] (C)
|
||||
Why should antenna loading coils have a high ratio of reactance to resistance? #card
|
||||
- [[A.]] To swamp out harmonics
|
||||
- [[B.]] To lower the radiation angle
|
||||
- [[C.]] To maximize efficiency
|
||||
- [[D.]] To minimize the Q
|
||||
--
|
||||
- [[E9D05]] (D)
|
||||
Approximately how long is a Yagi’s driven element? #card
|
||||
- [[A.]] 234 divided by frequency in MHz
|
||||
- [[B.]] 1005 divided by frequency in MHz
|
||||
- [[C.]] 1/4 wavelength
|
||||
- [[D.]] 1/2 wavelength
|
||||
--
|
||||
- [[E9D06]] (B)
|
||||
What happens to SWR bandwidth when one or more loading coils are used to resonate an electrically short antenna? #card
|
||||
- [[A.]] It is increased
|
||||
- [[B.]] It is decreased
|
||||
- [[C.]] It is unchanged if the loading coil is located at the feed point
|
||||
- [[D.]] It is unchanged if the loading coil is located at a voltage maximum point
|
||||
--
|
||||
- [[E9D07]] (D)
|
||||
What is an advantage of top loading an electrically short HF vertical antenna? #card
|
||||
- [[A.]] Lower Q
|
||||
- [[B.]] Greater structural strength
|
||||
- [[C.]] Higher losses
|
||||
- [[D.]] Improved radiation efficiency
|
||||
--
|
||||
- [[E9D08]] (B)
|
||||
What happens as the Q of an antenna increases? #card
|
||||
- [[A.]] SWR bandwidth increases
|
||||
- [[B.]] SWR bandwidth decreases
|
||||
- [[C.]] Gain is reduced
|
||||
- [[D.]] More common-mode current is present on the feed line
|
||||
--
|
||||
- [[E9D09]] (D)
|
||||
What is the function of a loading coil in an electrically short antenna? #card
|
||||
- [[A.]] To increase the SWR bandwidth by increasing net reactance
|
||||
- [[B.]] To lower the losses
|
||||
- [[C.]] To lower the Q
|
||||
- [[D.]] To resonate the antenna by cancelling the capacitive reactance
|
||||
--
|
||||
- [[E9D10]] (B)
|
||||
How does radiation resistance of a base-fed whip antenna change below its resonant frequency? #card
|
||||
- [[A.]] Radiation resistance increases
|
||||
- [[B.]] Radiation resistance decreases
|
||||
- [[C.]] Radiation resistance becomes imaginary
|
||||
- [[D.]] Radiation resistance does not depend on frequency
|
||||
--
|
||||
- [[E9D11]] (D)
|
||||
Why do most two-element Yagis with normal spacing have a reflector instead of a director? #card
|
||||
- [[A.]] Lower SWR
|
||||
- [[B.]] Higher receiving directivity factor
|
||||
- [[C.]] Greater front-to-side
|
||||
- [[D.]] Higher gain
|
||||
--
|
||||
- [[E9D12]] (C)
|
||||
What is the purpose of making a Yagi’s parasitic elements either longer or shorter than resonance? #card
|
||||
- [[A.]] Wind torque cancellation
|
||||
- [[B.]] Mechanical balance
|
||||
- [[C.]] Control of phase shift
|
||||
- [[D.]] Minimize losses
|
||||
Reference in New Issue
Block a user