| 1 |
What is the significance of the sunspot number with regard to HF propagation?
|
|---|---|
| A | Higher sunspot numbers generally indicate a greater probability of good propagation at higher frequencies |
| B | Lower sunspot numbers generally indicate greater probability of sporadic E propagation |
| C | A zero sunspot number indicate radio propagation is not possible in any band |
| D | All of these choices are correct. |
| 2 |
What effect does a Sudden Ionospheric Disturbance have on the daytime ionospheric propagation of HF radio waves?
|
|---|---|
| A | It enhances propagation on all HF frequencies |
| B | It disrupts signals on lower frequencies more than those on higher frequencies |
| C | It disrupts communications via satellite more than direct communications |
| D | None, because only areas on the night side of the Earth are affected |
| 3 |
Approximately how long does it take the increased ultraviolet and X-ray radiation from solar flares to affect radio propagation on the Earth?
|
|---|---|
| A | 28 days |
| B | 1 to 2 hours |
| C | 8 minutes |
| D | 20 to 40 hours |
| 4 |
What is the solar flux index?
|
|---|---|
| A | A measure of the highest frequency that is useful for ionospheric propagation between two points on the Earth |
| B | A count of sunspots which is adjusted for solar emissions |
| C | Another name for the Malaysian sunspot number |
| D | A measure of solar radiation at 10.7 centimetres wavelength |
| 5 |
What is a geomagnetic storm?
|
|---|---|
| A | A sudden drop in the solar flux index |
| B | A thunderstorm which affects radio propagation |
| C | Ripples in the ionosphere |
| D | A temporary disturbance in the Earth's magnetosphere |
| 6 |
At what point in the solar cycle does the 20-meter band usually support worldwide propagation during daylight hours?
|
|---|---|
| A | At the summer solstice |
| B | Only at the maximum point of the solar cycle |
| C | Only at the minimum point of the solar cycle |
| D | At any point in the solar cycle |
| 7 |
Which of the following effects can a geomagnetic storm have on radio propagation?
|
|---|---|
| A | Improved high-latitude HF propagation |
| B | Degraded high-latitude HF propagation |
| C | Improved ground-wave propagation |
| D | Improved chances of UHF ducting |
| 8 |
What effect does a high sunspot number have on radio communications?
|
|---|---|
| A | High-frequency radio signals become weak and distorted |
| B | Frequencies above 300 MHz become usable for long-distance communication |
| C | Long-distance communication in the upper HF and lower VHF range is enhanced |
| D | Microwave communications become unstable |
| 9 |
What causes HF propagation conditions to vary periodically in a 28-day cycle?
|
|---|---|
| A | Long-term oscillations in the upper atmosphere |
| B | Cyclic variation in the Earth’s radiation belts |
| C | The Sun’s rotation on its axis |
| D | The position of the Moon in its orbit |
| 10 |
Approximately how long is the typical sunspot cycle?
|
|---|---|
| A | 8 minutes |
| B | 40 hours |
| C | 28 days |
| D | 11 years |
| 11 |
What does the K-index indicate?
|
|---|---|
| A | The relative position of sunspots on the surface of the Sun |
| B | The short term stability of the Earth’s magnetic field |
| C | The stability of the Sun's magnetic field |
| D | The solar radio flux at Ayer Kuning Taiping, Perak |
| 12 |
What does the A-index indicate?
|
|---|---|
| A | The relative position of sunspots on the surface of the Sun |
| B | The amount of polarisation of the Sun's electric field |
| C | The long-term stability of the Earth’s geomagnetic field |
| D | The solar radio flux at Ayer Kuning Taiping, Perak |
| 13 |
How are radio communications usually affected by the charged particles that reach the Earth from solar coronal holes?
|
|---|---|
| A | HF communications are improved |
| B | HF communications are disturbed |
| C | VHF/UHF ducting is improved |
| D | VHF/UHF ducting is disturbed |
| 14 |
How long does it take charged particles from coronal mass ejections to affect radio propagation on the Earth?
|
|---|---|
| A | 28 days |
| B | 14 days |
| C | 4 to 8 minutes |
| D | 20 to 40 hours |
| 15 |
What is a possible benefit to radio communications resulting from periods of high geomagnetic activity?
|
|---|---|
| A | Auroras that can reflect VHF signals |
| B | Higher signal strength for HF signals passing through the polar regions |
| C | Improved HF long path propagation |
| D | Reduced long delayed echoes |
| 16 |
How might a sky-wave signal sound if it arrives at your receiver by both short path and long path propagation?
|
|---|---|
| A | Periodic fading approximately every 10 seconds |
| B | Signal strength increased by 3 dB |
| C | The signal might be cancelled causing severe attenuation |
| D | A well-defined echo might be heard |
| 17 |
Which of the following is a good indicator of the possibility of sky-wave propagation on the 6-meter band?
|
|---|---|
| A | Short skip sky-wave propagation on the 10-meter band |
| B | Long skip sky-wave propagation on the 10-meter band |
| C | Severe attenuation of signals on the 10-meter band |
| D | Long delayed echoes on the 10-meter band |
| 18 |
Which of the following applies when selecting a frequency for lowest attenuation when transmitting on HF?
|
|---|---|
| A | Select a frequency just below the MUF |
| B | Select a frequency just above the LUF |
| C | Select a frequency just below the critical frequency |
| D | Select a frequency just above the critical frequency |
| 19 |
What is a reliable way to determine if the MUF is high enough to support skip propagation between your station and a distant location on frequencies between 14 and 30 MHz?
|
|---|---|
| A | Listen for signals from an international beacon in the frequency range you plan to use |
| B | Send a series of dots on the band and listen for echoes from your signal |
| C | Check the strength of TV signals from Western Europe |
| D | Check the strength of signals in the MF AM broadcast band |
| 20 |
What usually happens to radio waves with frequencies below the MUF and above the LUF when they are sent into the ionosphere?
|
|---|---|
| A | They are bent back to the Earth |
| B | They pass through the ionosphere |
| C | They are amplified by interaction with the ionosphere |
| D | They are bent and trapped in the ionosphere to circle the Earth |
| 21 |
What usually happens to radio waves with frequencies below the LUF?
|
|---|---|
| A | They are bent back to the Earth |
| B | They pass through the ionosphere |
| C | They are completely absorbed by the ionosphere |
| D | They are bent and trapped in the ionosphere to circle the Earth |
| 22 |
What does LUF stand for?
|
|---|---|
| A | The Lowest Usable Frequency for communications between two points |
| B | The Longest Universal Function for communications between two points |
| C | The Lowest Usable Frequency during a 24-hour period |
| D | The Longest Universal Function during a 24-hour period |
| 23 |
What does MUF stand for?
|
|---|---|
| A | The Minimum Usable Frequency for communications between two points |
| B | The Maximum Usable Frequency for communications between two points |
| C | The Minimum Usable Frequency during a 24-hour period |
| D | The Maximum Usable Frequency during a 24-hour period |
| 24 |
What is the approximate maximum distance along the Earth's surface that is normally covered in one hop using the F2 region?
|
|---|---|
| A | 180 miles |
| B | 1,200 miles |
| C | 2,500 miles |
| D | 12,000 miles |
| 25 |
What is the approximate maximum distance along the Earth's surface that is normally covered in one hop using the E region?
|
|---|---|
| A | 180 miles |
| B | 1,200 miles |
| C | 2,500 miles |
| D | 12,000 miles |
| 26 |
What happens to HF propagation when the LUF exceeds the MUF?
|
|---|---|
| A | No HF radio frequency will support ordinary sky-wave communications over the path |
| B | HF communications over the path are enhanced |
| C | Double hop propagation along the path occurs |
| D | Propagation over the path on all HF frequencies is enhanced |
| 27 |
What factor or factors affect the MUF?
|
|---|---|
| A | Path distance and location |
| B | Time of day and season |
| C | Solar radiation and ionospheric disturbances |
| D | All of these choices are correct |
| 28 |
Which ionospheric layer is closest to the surface of the Earth?
|
|---|---|
| A | The D layer |
| B | The E layer |
| C | The F1 layer |
| D | The F2 layer |
| 29 |
Where on the Earth do ionospheric layers reach their maximum height?
|
|---|---|
| A | Where the Sun is overhead |
| B | Where the Sun is on the opposite side of the Earth |
| C | Where the Sun is rising |
| D | Where the Sun has just set |
| 30 |
Why is the F2 region mainly responsible for the longest distance radio wave propagation?
|
|---|---|
| A | Because it is the densest ionospheric layer |
| B | Because it does not absorb radio waves as much as other ionospheric regions |
| C | Because it is the highest ionospheric region |
| D | All of these choices are correct |
| 31 |
What does the term "critical angle" mean as used in radio wave propagation?
|
|---|---|
| A | The long path azimuth of a distant station |
| B | The short path azimuth of a distant station |
| C | The lowest takeoff angle that will return a radio wave to the Earth under specific ionospheric conditions |
| D | The highest takeoff angle that will return a radio wave to the Earth under specific ionospheric conditions |
| 32 |
Why is long distance communication on the 40-meter, 60-meter and 80-meter bands more difficult during the day?
|
|---|---|
| A | The F layer absorbs signals at these frequencies during daylight hours |
| B | The F layer is unstable during daylight hours |
| C | The D layer absorbs signals at these frequencies during daylight hours |
| D | The E layer is unstable during daylight hours |
| 33 |
What is a characteristic of HF scatter signals?
|
|---|---|
| A | They have high intelligibility |
| B | They have a wavering sound |
| C | They have very large swings in signal strength |
| D | All of these choices are correct |
| 34 |
What makes HF scatter signals often sound distorted?
|
|---|---|
| A | The ionospheric layer involved is unstable |
| B | Ground waves are absorbing much of the signal |
| C | The E-region is not present |
| D | Energy is scattered into the skip zone through several different radio wave paths |
| 35 |
Why are HF scatter signals in the skip zone usually weak?
|
|---|---|
| A | Only a small part of the signal energy is scattered into the skip zone |
| B | Signals are scattered from the magnetosphere which is not a good reflector |
| C | Propagation is through ground waves which absorb most of the signal energy |
| D | Propagations are through ducts in F region which absorb most of the energy |
| 36 |
What type of radio wave propagation allows a signal to be detected at a distance too far for ground wave propagation but too near for normal sky-wave propagation?
|
|---|---|
| A | Faraday rotation |
| B | Scatter |
| C | Sporadic-E skip |
| D | Short-path skip |
| 37 |
Which of the following might be an indication that signals heard on the HF bands are being received via scattering propagation?
|
|---|---|
| A | The communication is during a sunspot maximum |
| B | The communication is during a sudden ionospheric disturbance |
| C | The signal is heard on a frequency below the Maximum Usable Frequency |
| D | The signal is heard on a frequency above the Maximum Usable Frequency |
| 38 |
Which of the following antenna types will be most effective for skip communications on 40-meters during the day?
|
|---|---|
| A | A vertical antenna |
| B | A horizontal dipole placed between 1/8 and 1/4 wavelength above the ground |
| C | A left-hand circularly polarised antenna |
| D | A right-hand circularly polarised antenna |
| 39 |
Which ionospheric layer is the most absorbent of long skip signals during daylight hours on frequencies below 10 MHz?
|
|---|---|
| A | The F2 layer |
| B | The F1 layer |
| C | The E layer |
| D | The D layer |
| 40 |
What is Near Vertical Incidence Skywave (NVIS) propagation?
|
|---|---|
| A | Propagation near the MUF |
| B | Short distance MF or HF propagation using high elevation angles |
| C | Long path HF propagation at sunrise and sunset |
| D | Double hop propagation near the LUF |
| 41 |
Which of the following factors determines the characteristic impedance of a parallel conductor antenna feed line?
|
|---|---|
| A | The distance between the centres of the conductors and the radius of the conductors |
| B | The distance between the centres of the conductors and the length of the line |
| C | The radius of the conductors and the frequency of the signal |
| D | The frequency of the signal and the length of the line |
| 42 |
What are the typical characteristic impedances of coaxial cables used for antenna feed lines at amateur stations?
|
|---|---|
| A | 25 and 30 ohms |
| B | 50 and 75 ohms |
| C | 80 and 100 ohms |
| D | 500 and 750 ohms |
| 43 |
What is the characteristic impedance of flat ribbon TV type twin lead?
|
|---|---|
| A | 50 ohms |
| B | 75 ohms |
| C | 100 ohms |
| D | 300 ohms |
| 44 |
What might cause reflected power at the point where a feed line connects to an antenna?
|
|---|---|
| A | Operating an antenna at its resonant frequency |
| B | Using more transmitter power than the antenna can handle |
| C | Difference between feed line impedance and antenna feed point impedance |
| D | Feeding the antenna with unbalanced feed line |
| 45 |
How does the attenuation of coaxial cable change as the frequency of the signal it is carrying increases?
|
|---|---|
| A | Attenuation is independent of frequency |
| B | Attenuation increases |
| C | Attenuation decreases |
| D | Attenuation reaches a maximum at approximately 18 MHz |
| 46 |
In what units is RF feed line loss usually expressed?
|
|---|---|
| A | Ohms per 1000 feet |
| B | Decibels per 1000 feet |
| C | Ohms per 100 feet |
| D | Decibels per 100 feet |
| 47 |
What must be done to prevent standing waves on an antenna feed line?
|
|---|---|
| A | The antenna feed point must be at DC ground potential |
| B | The feed line trim to a length equal to an odd number of electrical quarter wavelengths |
| C | The feed line must trim to a length equal to an even number of physical half wavelengths |
| D | The antenna feed point impedance matched to the characteristic impedance of the feed line |
| 48 |
If the SWR on an antenna feed line 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 feed line?
|
|---|---|
| A | 1 to 1 |
| B | 5 to 1 |
| C | Between 1 to 1 and 5 to 1 depending on the characteristic impedance of the line |
| D | Between 1 to 1 and 5 to 1 depending on the reflected power at the transmitter |
| 49 |
What standing wave ratio will result when connecting a 50-ohm feedline to a non-reactive load having 200-ohm impedance?
|
|---|---|
| A | 4:1 |
| B | 1:4 |
| C | 2:1 |
| D | 1:2 |
| 50 |
What standing wave ratio will result when connecting a 50-ohm feedline to a non-reactive load having 10-ohm impedance?
|
|---|---|
| A | 2:1 |
| B | 50:1 |
| C | 1:5 |
| D | 5:1 |
| 51 |
What standing wave ratio will result when connecting a 50-ohm feedline to a non-reactive load having 50-ohm impedance?
|
|---|---|
| A | 2:1 |
| B | 1:1 |
| C | 50:50 |
| D | 0:0 |
| 52 |
What standing wave ratio will result when connecting a 50-ohm feedline to a non-reactive load having 25-ohm impedance?
|
|---|---|
| A | 2:1 |
| B | 2.5:1 |
| C | 1.25:1 |
| D | UN-determine SWR value |
| 53 |
What standing wave ratio will result when connecting a 50-ohm feed line to an antenna that has a purely resistive 300-ohm feed point impedance?
|
|---|---|
| A | 1.5:1 |
| B | 3:1 |
| C | 6:1 |
| D | Un-determine SWR from impedance values |
| 54 |
What is the interaction between high standing wave ratio (SWR) and transmission line loss?
|
|---|---|
| A | There is no interaction between transmission line loss and SWR |
| B | If a transmission line is lossy, high SWR will increase the loss |
| C | High SWR makes it difficult to measure transmission line loss |
| D | High SWR reduces the relative effect of transmission line loss |
| 55 |
What is the effect of transmission line loss on SWR measured at the input to the line?
|
|---|---|
| A | The higher the transmission line loss, the more the SWR will read artificially low |
| B | The higher the transmission line loss, the more the SWR will read artificially high |
| C | The higher the transmission line loss, the more accurate the SWR measurement will be |
| D | Transmission line loss does not affect the SWR measurement |
| 56 |
What is one disadvantage of a directly fed random wire HF antenna?
|
|---|---|
| A | It must be longer than one wavelength |
| B | User experience RF burns when touching metal objects |
| C | It produces only vertically polarised radiation |
| D | It is more effective on the lower HF bands than on, the higher bands |
| 57 |
Which of the following is a common way to adjust the feed point impedance of a quarter wave ground vertical plane antenna to be approximately 50 ohms?
|
|---|---|
| A | Slope the radials upward |
| B | Slope the radials downward |
| C | Lengthen the radials |
| D | Shorten the radials |
| 58 |
What happens to the feed point impedance of a ground plane antenna when its radials changed from horizontal to sloping downward?
|
|---|---|
| A | It decreases |
| B | It increases |
| C | It stays the same |
| D | It reaches a maximum at an angle of 45 degrees |
| 59 |
What is the radiation pattern of a dipole antenna in free space in the plane of the conductor?
|
|---|---|
| A | It is a figure-eight at right angles to the antenna |
| B | It is a figure-eight off both ends of the antenna |
| C | It is a circle (equal radiation in all directions) |
| D | It has a pair of lobes on one side of the antenna and a single lobe on the other side |
| 60 |
How does antenna height affect the horizontal (azimuthal) radiation pattern of a horizontal dipole HF antenna?
|
|---|---|
| A | If the antenna is too high, the pattern becomes unpredictable |
| B | Antenna height has no effect on the pattern |
| C | If the antenna is less than 1/2 wavelength high, the azimuthal pattern is almost omnidirectional |
| D | If the antenna is less than 1/2 wavelength high, radiation off the ends of the wire eliminated |
| 61 |
The radial wires of a ground-mounted vertical antenna system should be placed:
|
|---|---|
| A | As high as possible above the ground |
| B | Parallel to the antenna element |
| C | On the surface of the Earth or buried a few inches below the ground |
| D | At the centre of the antenna |
| 62 |
How does the feed point impedance of a 1/2 wave dipole antenna change as the antenna lowered below 1/4 wave above ground?
|
|---|---|
| A | It steadily increases |
| B | It steadily decreases |
| C | It peaks at about 1/8 wavelength above ground |
| D | It is unaffected by the height above ground |
| 63 |
How does the feed point impedance of a 1/2 wave dipole change as the feed point is moved from the centre toward the ends?
|
|---|---|
| A | It steadily increases |
| B | It steadily decreases |
| C | It peaks at about 1/8 wavelength from the end |
| D | It is unaffected by the location of the feed point |
| 64 |
Which of the following is an advantage of a horizontally polarised as compared to a vertically polarised HF antenna?
|
|---|---|
| A | Lower ground reflection losses |
| B | Lower feed point impedance |
| C | Shorter Radials |
| D | Lower radiation resistance |
| 65 |
What is the approximate length of a 1/2 wave dipole antenna cut for 14.250 MHz?
|
|---|---|
| A | 8 feet |
| B | 16 feet |
| C | 24 feet |
| D | 32 feet |
| 66 |
What is the approximate length of a 1/2 wave dipole antenna cut for 3.550 MHz?
|
|---|---|
| A | 42 feet |
| B | 84 feet |
| C | 131 feet |
| D | 263 feet |
| 67 |
What is the approximate length of a 1/4 wave vertical antenna cut for 28.5 MHz?
|
|---|---|
| A | 8 feet |
| B | 11 feet |
| C | 16 feet |
| D | 21 feet |
| 68 |
Which of the following would increase the bandwidth of a Yagi antenna?
|
|---|---|
| A | Larger diameter elements |
| B | Closer element spacing |
| C | Loading coils in series with the element |
| D | Tapered-diameter elements |
| 69 |
What is the approximate length of the driven element of a Yagi antenna?
|
|---|---|
| A | 1/4 wavelength |
| B | 1/2 wavelength |
| C | 3/4 wavelength |
| D | 1 wavelength |
| 70 |
Which statement about a three-element, single-band Yagi antenna is true?
|
|---|---|
| A | The reflector is normally the shortest element |
| B | The director is normally the shortest element |
| C | The driven element is the longest element |
| D | Low feed point impedance increases bandwidth |
| 71 |
Which statement about a three-element, single-band Yagi antenna is true?
|
|---|---|
| A | The reflector is normally the longest element |
| B | The director is normally the longest element |
| C | The reflector is normally the shortest element |
| D | All of the elements must be the same length |
| 72 |
How does increasing boom length and adding directors affect a Yagi antenna?
|
|---|---|
| A | Gain increases |
| B | Beamwidth increases |
| C | Front to back ratio decreases |
| D | Front to side ratio decreases |
| 73 |
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 used as a reflector?
|
|---|---|
| A | The driven element must feed with a balun transformer |
| B | There must be an open circuit in the driven element at the point opposite the feed point |
| C | The reflector element must be approximately 5 percent shorter than the driven element |
| D | The reflector element must be approximately 5 percent longer than the driven element |
| 74 |
What does "front-to-back ratio" mean about a Yagi antenna?
|
|---|---|
| A | The number of directors versus the number of reflectors |
| B | The relative position of the driven element on the reflectors and directors |
| C | The power radiated in the major radiation lobe compared to the power radiated in exactly the opposite direction |
| D | The ratio of forward gain to dipole gain |
| 75 |
The elaboration of the main lobe referred as:
|
|---|---|
| A | The magnitude of the maximum vertical angle of radiation |
| B | The point of maximum current in a radiating antenna element |
| C | The maximum voltage standing wave point on a radiating element |
| D | The direction of maximum radiated field strength from the antenna |
| 76 |
How does the gain of two 3-element horizontally polarised Yagi antennas spaced vertically 1/2 wavelength apart typically compare to the gain of a single 3-element Yagi?
|
|---|---|
| A | Approximately 1.5 dB higher |
| B | Approximately 3 dB higher |
| C | Approximately 6 dB higher |
| D | Approximately 9 dB higher |
| 77 |
Which of the following is a Yagi antenna design variable that could be adjusted to optimise forward gain, front-to-back ratio, or SWR bandwidth?
|
|---|---|
| A | The physical length of the boom |
| B | The number of elements on the boom |
| C | The spacing of each element along the boom |
| D | All of these choices are correct |
| 78 |
What is the purpose of a gamma match used with Yagi antennas?
|
|---|---|
| A | To match the relatively low feed point impedance to 50 ohms |
| B | To match the relatively high feed point impedance to 50 ohms |
| C | To increase the front-to-back ratio |
| D | To increase the main lobe gain |
| 79 |
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?
|
|---|---|
| A | It does not require that the elements insulated from the boom |
| B | It does not require any inductors or capacitors |
| C | It is useful for matching multiband antennas |
| D | All of these choices are correct |
| 80 |
Approximately how long is each side of the driven element of a quad antenna?
|
|---|---|
| A | 1/4 wavelength |
| B | 1/2 wavelength |
| C | 3/4 wavelength |
| D | 1 wavelength |
| 81 |
How does the forward gain of a two-element quad antenna compare to the forward gain of a three-element Yagi antenna?
|
|---|---|
| A | About 2/3 as much |
| B | About the same |
| C | About 1.5 times as much |
| D | About twice as much |
| 82 |
Approximately how long is each side of the reflector element of a quad antenna?
|
|---|---|
| A | Slightly less than 1/4 wavelength |
| B | Slightly more than 1/4 wavelength |
| C | Slightly less than 1/2 wavelength |
| D | Slightly more than 1/2 wavelength |
| 83 |
How does the gain of a two-element delta loop beam compare to the gain of a two-element quad antenna?
|
|---|---|
| A | 3 dB higher |
| B | 3 dB lower |
| C | 2.54 dB higher |
| D | About the same |
| 84 |
Approximately how long is each leg of a symmetrical delta-loop antenna?
|
|---|---|
| A | 1/4 wavelength |
| B | 1/3 wavelength |
| C | 1/2 wavelength |
| D | 2/3 wavelength |
| 85 |
What happens when the feed point of a quad antenna of any shape moved from the midpoint of the top or bottom to the midpoint of either side?
|
|---|---|
| A | The polarisation of the radiated signal changes from horizontal to vertical |
| B | The polarisation of the radiated signal changes from vertical to horizontal |
| C | There is no change in polarisation |
| D | The radiated signal becomes circularly polarised |
| 86 |
How does antenna gain stated in dBi compare to gain stated in dBd for the same antenna?
|
|---|---|
| A | dBi gain figures are 2.15 dB lower than dBd gain figures |
| B | dBi gain figures are 2.15 dB higher than dBd gain figures |
| C | dBi gain figures are the same as the square root of dBd gain figures multiplied by 2.15 |
| D | dBi gain figures are the reciprocal of dBd gain figures + 2.15 dB |
| 87 |
What is meant by the terms dBi and dBd when referring to antenna gain?
|
|---|---|
| A | dBi refers to an isotropic antenna; dBd refers to a dipole antenna |
| B | dBi refers to an ionospheric reflecting antenna; dBd refers to a dissipative antenna |
| C | dBi refers to an inverted-vee antenna; dBd refers to a downward reflecting antenna |
| D | dBi refers to an isometric antenna; dBd refers to a discone antenna |
| 88 |
What does the term NVIS mean as related to antennas?
|
|---|---|
| A | Nearly Vertical Inductance System |
| B | Non-Varying Indicated SWR |
| C | Non-Varying Impedance Smoothing |
| D | Near Vertical Incidence sky-wave |
| 89 |
Which of the following is an advantage of an NVIS antenna?
|
|---|---|
| A | Low vertical angle radiation for working stations out to ranges of several thousand kilometres |
| B | High vertical angle radiation for working stations within a radius of a few hundred kilometres |
| C | High forward gain |
| D | All of these choices are correct |
| 90 |
At what height above ground is an NVIS antenna typically installed?
|
|---|---|
| A | As close to 1/2 wavelength as possible |
| B | As close to one wavelength as possible |
| C | Height is not critical as long as it is significantly more than 1/2 wavelength |
| D | Between 1/10 and 1/4 wavelength |
| 91 |
What is the primary purpose of antenna traps?
|
|---|---|
| A | To permit multiband operation |
| B | To notch spurious frequencies |
| C | To provide balanced feed point impedance |
| D | To prevent out of band operation |
| 92 |
What is an advantage of vertical stacking of horizontally polarised Yagi antennas?
|
|---|---|
| A | It allows quick selection of vertical or horizontal polarisation |
| B | It allows simultaneous vertical and horizontal polarisation |
| C | It narrows the main lobe in azimuth |
| D | It narrows the main lobe in elevation |
| 93 |
Which of the following is an advantage of a log periodic antenna?
|
|---|---|
| A | Wide bandwidth |
| B | Higher gain per element than a Yagi antenna |
| C | Harmonic suppression |
| D | Polarization diversity |
| 94 |
Which of the following describes a log periodic antenna?
|
|---|---|
| A | Length and spacing of the elements increase logarithmically from one end of the boom to the other |
| B | Impedance varies periodically as a function of frequency |
| C | Gain varies logarithmically as a function of frequency |
| D | SWR varies periodically as a function of boom length |
| 95 |
Why is a Beverage antenna not used for transmitting?
|
|---|---|
| A | Its impedance is too low for effective matching |
| B | It has high losses compared to other types of antennas |
| C | It has poor directivity |
| D | All of these choices are correct |
| 96 |
Which of the following is an application for a Beverage antenna?
|
|---|---|
| A | Directional transmitting for low HF bands |
| B | Directional receiving for low HF bands |
| C | Portable direction finding at higher HF frequencies |
| D | Portable direction finding at lower HF frequencies |
| 97 |
Which of the following describes a Beverage antenna?
|
|---|---|
| A | A vertical antenna |
| B | A broadband mobile antenna |
| C | A helical antenna for space reception |
| D | A very long and low directional receiving antenna |
| 98 |
Which of the following is a disadvantage of multiband antennas?
|
|---|---|
| A | Present low impedance on all design frequencies |
| B | Must equipped with an antenna tuner |
| C | Must fed with open wire line |
| D | They have poor harmonic rejection |