G2D04 What is an azimuthal projection map? - PowerPoint PPT Presentation

1 / 62
About This Presentation
Title:

G2D04 What is an azimuthal projection map?

Description:

A world map that shows accurate land masses. A world map projection centered on a particular location A world map that shows the angle at which an amateur satellite ... – PowerPoint PPT presentation

Number of Views:68
Avg rating:3.0/5.0
Slides: 63
Provided by: K3D9
Category:

less

Transcript and Presenter's Notes

Title: G2D04 What is an azimuthal projection map?


1
G2D04 What is an azimuthal projection map?
  1. A world map that shows accurate land masses.
  2. A world map projection centered on a particular
    location
  3. A world map that shows the angle at which an
    amateur satellite crosses the equator
  4. A world map that shows the number of degrees
    longitude that an amateur satellite appears to
    move westward at the equator with each orbit

2
G2D11 Which HF antenna would be the best to
use for minimizing interference?
  1. A quarter wave vertical antenna
  2. An isotropic antenna
  3. A unidirectional antenna
  4. An omnidirectional antenna

3
G4A06 What type of device is often used to
enable matching the transmitter output to an
impedance other than 50 ohms?
  1. Balanced modulator.
  2. SWR Bridge.
  3. Antenna coupler.
  4. Q Multiplier.

4
G4E01 What is a capacitance hat when
referring to a mobile antenna?
  1. A device to increase the power handling capacity
    of a mobile whip antenna.
  2. A device that allows automatic band-changing for
    a mobile antenna.
  3. A device to electrically lengthen a physically
    short antenna.
  4. A device that allows remote tuning of a mobile
    antenna.

5
G4E02 What is the purpose of a corona ball
on a HF mobile antenna?
  1. To narrow the operating bandwidth of the antenna.
  2. To increase the Q of the antenna.
  3. To reduce the chance of damage if the antenna
    should strike an object.
  4. To reduce high voltage discharge from the tip of
    the antenna.

6
G4E06 What is one disadvantage of using a
shortened mobile antenna as opposed to a
full size antenna?
  1. Short antennas are more likely to cause
    distortion of transmitted signals.
  2. Short antennas can only receive vertically
    polarized signals.
  3. Operating bandwidth may be very limited.
  4. Harmonic radiation may increase.

7
G9A01 Which of the following factors determine
the characteristic impedance of a parallel
conductor antenna feed line?
  1. The distance between the centers of the
    conductors and the radius of the conductors
  2. The distance between the centers of the
    conductors and the length of the line
  3. The radius of the conductors and the frequency of
    the signal
  4. The frequency of the signal and the length of the
    line

8
G9A02 What are the typical characteristic
impedances of coaxial cables used for antenna
feed lines at amateur stations?
  1. 25 and 30 ohms
  2. 50 and 75 ohms
  3. 80 and 100 ohms
  4. 500 and 750 ohms

9
G9A03 What is the characteristic impedance of
flat ribbon TV type twinlead?
  1. 50 ohms
  2. 75 ohms
  3. 100 ohms
  4. 300 ohms

10
G9A04 What is the reason for the occurrence of
reflected power at the point where a feedline
connects to an antenna?
  1. Operating an antenna at its resonant frequency
  2. Using more transmitter power than the antenna can
    handle
  3. A difference between feed line impedance and
    antenna feed point impedance
  4. Feeding the antenna with unbalanced feedline

11
G9A05 How does the attenuation of coaxial cable
change as the frequency of the signal it is
carrying increases?
  1. It is independent of frequency
  2. It increases
  3. It decreases
  4. It reaches a maximum at approximately 18 MHz

12
G9A06 In what values are RF feed line losses
usually expressed?
  1. Ohms per 1000 ft
  2. dB per 1000 ft
  3. Ohms per 100 ft
  4. dB per 100 ft

13
G9A07 What must be done to prevent standing
waves on an antenna feed line?
  1. The antenna feed point must be at DC ground
    potential
  2. The feedline must be cut to an odd number of
    electrical quarter wavelengths long
  3. The feedline must be cut to an even number of
    physical half wavelengths long
  4. The antenna feed point impedance must be matched
    to the characteristic impedance of the feed line

14
G9A08 If the SWR on an antenna feedline is 5 to
1, and a matching network at the transmitter
end of the feedline is adjusted to 1 to 1 SWR,
what is the resulting SWR on the feedline?
  1. 1 to 1
  2. 5 to 1
  3. Between 1 to 1 and 5 to 1 depending on the
    characteristic impedance of the line
  4. Between 1 to 1 and 5 to 1 depending on the
    reflected power at the transmitter

15
G9A09 What standing-wave-ratio will result from
the connection of a 50-ohm feed line to a
non- reactive load having a 200-ohm impedance?
  1. 41
  2. 14
  3. 21
  4. 12

16
G9A10 What standing-wave-ratio will result from
the connection of a 50-ohm feed line to a
non- reactive load having a 10-ohm impedance?
  1. 21
  2. 501
  3. 15
  4. 51

17
G9A11 What standing-wave-ratio will result from
the connection of a 50-ohm feed line to a
non- reactive load having a 50-ohm impedance?
  1. 21
  2. 11
  3. 5050
  4. 00

18
G9A12 What would be the SWR if you feed a
vertical antenna that has a 25-ohm feed-point
impedance with 50-ohm coaxial cable?
  1. 21
  2. 2.51
  3. 1.251
  4. You cannot determine SWR from impedance values

19
G9A13 What would be the SWR if you feed a folded
dipole antenna that has a 300-ohm feed-point
impedance with 50-ohm coaxial cable?
  1. 1.51
  2. 31
  3. 61
  4. You cannot determine SWR from impedance values

20
G9B01 What is one disadvantage of a directly
fed random-wire antenna?
  1. It must be longer than 1 wavelength
  2. You may experience RF burns when touching metal
    objects in your station
  3. It produces only vertically polarized radiation
  4. It is not effective on the higher HF bands

21
G9B02 What is an advantage of downward sloping
radials on a quarter wave ground-plane antenna?
  1. They lower the radiation angle
  2. They bring the feed-point impedance closer to 300
    ohms
  3. They increase the radiation angle
  4. They bring the feed-point impedance closer to 50
    ohms

22
G9B03 What happens to the feed-point impedance
of a ground-plane antenna when its radials are
changed from horizontal to downward-sloping?
  1. It decreases
  2. It increases
  3. It stays the same
  4. It reaches a maximum at an angle of 45 degrees

23
G9B04 What is the low angle azimuthal radiation
pattern of an ideal half-wavelength dipole
antenna installed 1/2 wavelength high and
parallel to the Earth?
  1. It is a figure-eight at right angles to the
    antenna
  2. It is a figure-eight off both ends of the antenna
  3. It is a circle (equal radiation in all
    directions)
  4. It has a pair of lobes on one side of the antenna
    and a single lobe on the other side

24
G9B05 How does antenna height affect the
horizontal (azimuthal) radiation pattern of a
horizontal dipole HF antenna?
  1. If the antenna is too high, the pattern becomes
    unpredictable
  2. Antenna height has no effect on the pattern
  3. If the antenna is less than 1/2 wavelength high,
    the azimuthal pattern is almost omnidirectional
  4. If the antenna is less than 1/2 wavelength high,
    radiation off the ends of the wire is
    eliminated

25
G9B06 Where should the radial wires of a
ground-mounted vertical antenna system be
placed?
  1. As high as possible above the ground
  2. Parallel to the antenna element
  3. On the surface or buried a few inches below the
    ground
  4. At the top of the antenna

26
G9B07 How does the feed-point impedance of a 1/2
wave dipole antenna change as the antenna is
lowered from 1/4 wave above ground?
  1. It steadily increases
  2. It steadily decreases
  3. It peaks at about 1/8 wavelength above ground
  4. It is unaffected by the height above ground

27
G9B08 How does the feed-point impedance of a 1/2
wave dipole change as the feed-point location
is moved from the center toward the ends?
  1. It steadily increases
  2. It steadily decrease
  3. It peaks at about 1/8 wavelength from the end
  4. It is unaffected by the location of the feed-point

28
G9B09 Which of the following is an advantage of
a horizontally polarized as compared to
vertically polarized HF antenna?
  1. Lower ground reflection losses
  2. Lower feed-point impedance
  3. Shorter Radials
  4. Lower radiation resistance

29
G9B10 What is the approximate length for a
1/2-wave dipole antenna cut for 14.250 MHz?
  1. 8 feet
  2. 16 feet
  3. 24 feet
  4. 32 feet

30
G9B11 What is the approximate length for a
1/2-wave dipole antenna cut for 3.550 MHz?
  1. 42 feet
  2. 84 feet
  3. 131 feet
  4. 263 feet

31
G9B12 What is the approximate length for a
1/4-wave vertical antenna cut for 28.5 MHz?
  1. 8 feet
  2. 11 feet
  3. 16 feet
  4. 21 feet

32
G9C01 Which of the following would increase
the bandwidth of a Yagi antenna?
  1. Larger diameter elements
  2. Closer element spacing
  3. Loading coils in series with the elements
  4. Tapered-diameter elements

33
G9C02 What is the approximate length of the
driven element of a Yagi antenna?
  1. 1/4 wavelength
  2. 1/2 wavelength
  3. 3/4 wavelength
  4. 1 wavelength

34
G9C03 Which statement about a three-element
single-band Yagi antenna is true?
  1. The reflector is normally the shortest parasitic
    element
  2. The director is normally the shortest parasitic
    element
  3. The driven element is the longest parasitic
    element
  4. Low feed-point impedance increases bandwidth

35
G9C04 Which statement about a three-element,
single-band Yagi antenna is true?
  1. The reflector is normally the longest parasitic
    element
  2. The director is normally the longest parasitic
    element
  3. The reflector is normally the shortest parasitic
    element
  4. All of the elements must be the same length

36
G9C05 How does increasing boom length and
adding directors affect a Yagi antenna?
  1. Gain increases
  2. Beamwidth increases
  3. Weight decreases
  4. Wind load decreases

37
G9C06 Which of the following is a reason why a
Yagi antenna is often used for radio
communications on the 20 meter band?
  1. It provides excellent omnidirectional coverage in
    the horizontal plane
  2. It is smaller, less expensive and easier to erect
    than a dipole or vertical antenna
  3. It helps reduce interference from other stations
    to the side or behind the antenna
  4. It provides the highest possible angle of
    radiation for the HF bands

38
G9C07 What does "front-to-back ratio" mean in
reference to a Yagi antenna?
  1. The number of directors versus the number of
    reflectors
  2. The relative position of the driven element with
    respect to the reflectors and directors
  3. The power radiated in the major radiation lobe
    compared to the power radiated in exactly the
    opposite direction
  4. The ratio of forward gain to dipole gain

39
G9C08 What is meant by the "main lobe" of a
directive antenna?
  1. The magnitude of the maximum vertical angle of
    radiation
  2. The point of maximum current in a radiating
    antenna element
  3. The maximum voltage standing wave point on a
    radiating element
  4. The direction of maximum radiated field strength
    from the antenna

40
G9C09 What is the approximate maximum
theoretical forward gain of a 3 element
single-band Yagi antenna?
  1. 9.7 dBi
  2. 9.7 dBd
  3. 5.4 times the gain of a dipole
  4. All of these choices are correct

41
G9C10 Which of the following is a Yagi antenna
design variable that could be adjusted to
optimize forward gain, front-to-back ratio, or
SWR bandwidth?
  1. The physical length of the boom
  2. The number of elements on the boom
  3. The spacing of each element along the boom
  4. All of these choices are correct

42
G9C11 What is the purpose of a gamma match
used with Yagi antennas?
  1. To match the relatively low feed-point impedance
    to 50 ohms
  2. To match the relatively high feed-point impedance
    to 50 ohms
  3. To increase the front to back ratio
  4. To increase the main lobe gain

43
G9C12 Which of the following is an advantage of
using a gamma match for impedance matching of a
Yagi antenna to 50-ohm coax feed line?
  1. It does not require that the elements be
    insulated from the boom.
  2. It does not require any inductors or capacitors.
  3. It is useful for matching multiband antennas.
  4. All of these choices are correct.

44
G9C13 Approximately how long is each side of a
quad antenna driven element?
  1. ¼ wavelength.
  2. ½ wavelength.
  3. ¾ wavelength.
  4. 1 wavelength.

45
G9C14 How does the forward gain of a two-element
quad antenna compare to the forward gain
of a three-element Yagi antenna?
  • About 2/3 as much.
  • About the same.
  • About 1.5 times as much.
  • About twice as much.

46
G9C15 Approximately how long is each side of a
quad antenna reflector element?
  1. Slightly less than ¼ wavelength
  2. Slightly more than ¼ wavelength
  3. Slightly less than ½ wavelength
  4. Slightly more than ½ wavelength

47
G9C16 How does the gain of a two- element
delta-loop beam compare to the gain of a
two-element quad antenna?
  1. 3 dB higher
  2. 3 dB lower
  3. 2.54 dB higher
  4. About the same

48
G9C17 Approximately how long is each leg of a
symmetrical delta-loop antenna?
  1. ¼ wavelengths
  2. 1/3 wavelengths
  3. ½ wavelengths
  4. 2/3 wavelengths

49
G9C18 What happens when the feed point of a quad
antenna is changed from the center of either
horizontal wire to the center of either
vertical wire?
  1. The polarization of the radiated signal changes
    from horizontal to vertical
  2. The polarization of the radiated signal changes
    from vertical to horizontal
  3. The direction of the main lobe is reversed
  4. The radiated signal changes to an omnidirectional
    pattern

50
G9C19 What configuration of the loops of a
two-element quad antenna must be used for the
antenna to operate as a beam antenna, assuming
one of the elements is used as a reflector?
  1. The driven element must be fed with a balun
    transformer.
  2. The driven element must be open-circuited on the
    side opposite the feed point.
  3. The reflector element must be approximately 5
    shorter than the driven element.
  4. The reflector element must be approximately 5
    longer than the driven element.

51
G9C20 How does the gain of two 3-element
horizontally polarized Yagi antennas spaced
vertically 1/2 wave apart from each another
typically compare to the gain of a single
3-element Yagi?
  1. Approximately 1.5 dB higher
  2. Approximately 3 dB higher
  3. Approximately 6 dB higher
  4. Approximately 9 dB higher

52
G9D01 What does the term "NVIS" mean as
related to antennas?
  1. Nearly Vertical Inductance System
  2. Non-Visible Installation Specification
  3. Non-Varying Impedance Smoothing
  4. Near Vertical Incidence Skywave

53
G9D02 Which of the following is an advantage
of an NVIS antenna?
  1. Low vertical angle radiation for working stations
    out to ranges of several thousand kilometers.
  2. High vertical angle radiation for working
    stations within a radius of a few hundred
    kilometers.
  3. High forward gain
  4. All of these choices are correct

54
G9D03 At what height above ground is an NVIS
antenna typically installed?
  1. As close to one-half wave as possible
  2. As close to one wavelength as possible
  3. Height is not critical as long as it is
    significantly more than 1/2 wavelength
  4. Between 1/10 and 1/4 wavelength

55
G9D04 What is the primary purpose of antenna
traps?
  1. To permit multiband operation
  2. To notch spurious frequencies
  3. To provide balanced feed-point impedance
  4. To prevent out of band operation

56
G9D05 What is the advantage of vertical stacking
of horizontally polarized Yagi antennas?
  1. Allows quick selection of vertical or horizontal
    polarization
  2. Allows simultaneous vertical and horizontal
    polarization
  3. Narrows the main lobe in azimuth
  4. Narrows the main lobe in elevation

57
G9D06 Which of the following is an advantage
of a log periodic antenna?
  1. Wide bandwidth
  2. Higher gain per element than a Yagi antenna
  3. Harmonic suppression
  4. Polarization diversity

58
G9D07 Which of the following describes a log
periodic antenna?
  1. Length and spacing of element increases
    logarithmically from one end of the boom to the
    other
  2. Impedance varies periodically as a function of
    frequency
  3. Gain varies logarithmically as a function of
    frequency
  4. SWR varies periodically as a function of boom
    length

59
G9D08 Why is a Beverage antenna generally not
used for transmitting?
  1. It's impedance is too low for effective matching
  2. It has high losses compared to other types of
    antennas
  3. It has poor directivity
  4. All of these choices are correct

60
G9D09 Which of the following is an application
for a Beverage antenna?
  1. Directional transmitting for low HF bands
  2. Directional receiving for low HF bands
  3. Portable direction finding at higher HF
    frequencies
  4. Portable direction finding at lower HF frequencies

61
G9D10 Which of the following describes a
Beverage antenna?
  1. A vertical antenna constructed from beverage cans
  2. A broad-band mobile antenna
  3. A helical antenna for space reception
  4. A very long and low directional receiving antenna

62
G9D11 Which of the following is a disadvantage
of multiband antennas?
  1. They present low impedance on all design
    frequencies
  2. They must be used with an antenna tuner
  3. They must be fed with open wire line
  4. They have poor harmonic rejection
Write a Comment
User Comments (0)
About PowerShow.com