E9D Space and satellite communications
antennas: gain; beamwidth;
tracking; losses in real antennas and matching: resistivity losses,
losses in resonating elements (loading coils, matching networks, etc.
{ie,
mobile, trap}); SWR bandwidth; efficiency
E9D01
(A)
What
factors determine the receiving antenna gain required at an amateur satellite
station in earth operation?
A. Height, transmitter power
and antennas of satellite
B. Length of transmission line and impedance
match between receiver and transmission line
C. Preamplifier location on transmission line
and presence or absence of RF amplifier stages
D. Height of earth antenna and satellite orbit
E9D02
(A)
What
factors determine the EIRP required by an amateur satellite station in earth
operation?
A. Satellite antennas and
height, satellite receiver sensitivity
B. Path loss, earth antenna gain,
signal-to-noise ratio
C. Satellite transmitter power and orientation
of ground receiving antenna
D. Elevation of satellite above horizon, signal-to-noise
ratio, satellite transmitter power
E9D03
(B)
What is
the beamwidth of a symmetrical pattern antenna with a gain of 20 dB as compared
to an isotropic radiator?
A. 10.1 degrees
B. 20.3 degrees
C. 45.0 degrees
D. 60.9 degrees
E9D04
(C)
How
does the gain of a parabolic dish antenna change when the operating frequency
is doubled?
A. Gain does not change
B. Gain is multiplied by 0.707
C. Gain increases 6 dB
D. Gain increases 3 dB
E9D05
(C)
How is
circular polarization produced using linearly polarized antennas?
A. Stack two Yagis, fed 90 degrees out of
phase, to form an array with the respective elements in parallel planes
B. Stack two Yagis, fed in phase, to form an
array with the respective elements in parallel planes
C. Arrange two Yagis
perpendicular to each other, with the driven elements in the same plane, fed 90
degrees out of phase
D. Arrange two Yagis perpendicular to each
other, with the driven elements in the same plane, fed in phase
E9D06
(D)
How
does the beamwidth of an antenna vary as the gain is increased?
A. It increases geometrically
B. It increases arithmetically
C. It is essentially unaffected
D. It decreases
E9D07
(A)
Why
does a satellite communications antenna system for earth operation need to have
rotators for both azimuth and elevation control?
A. In order to track the
satellite as it orbits the earth
B. Because the antennas are large and heavy
C. In order to point the antenna above the
horizon to avoid terrestrial interference
D. To rotate antenna polarization along the
azimuth and elevate the system towards the satellite
E9D08
(A)
For a
shortened vertical antenna, where should a loading coil be placed to minimize
losses and produce the most effective performance?
A. Near the center of the
vertical radiator
B. As low as possible on the vertical radiator
C. As close to the transmitter as possible
D. At a voltage node
E9D09
(C)
Why
should an HF mobile antenna loading coil have a high ratio of reactance to
resistance?
A. To swamp out harmonics
B. To maximize losses
C. To minimize losses
D. To minimize the Q
E9D10
(A)
What is
a disadvantage of using a trap antenna?
A. It will radiate harmonics
B. It can only be used for single-band
operation
C. It is too sharply directional at lower
frequencies
D. It must be neutralized
E9D11
(A)
How
must the driven element in a 3-element Yagi be tuned to use a
"hairpin" matching system?
A. The driven element
reactance is capacitive
B. The driven element reactance is inductive
C. The driven element resonance is higher than
the operating frequency
D. The driven element radiation resistance is
higher than the characteristic impedance of the transmission line
E9D12
(C)
What is
the equivalent lumped-constant network for a "hairpin" matching
system on a 3-element Yagi?
A. Pi network
B. Pi-L network
C. L network
D. Parallel-resonant tank
E9D13
(B)
What
happens to the bandwidth of an antenna as it is shortened through the use of
loading coils?
A. It is increased
B. It is decreased
C. No change occurs
D. It becomes flat
E9D14
(D)
What is
an advantage of using top loading in a shortened HF vertical antenna?
A. Lower Q
B. Greater structural strength
C. Higher losses
D. Improved radiation
efficiency