subelement g9 antennas and feedlines [4 exam questions–4 groups] antennas & feedlines1

SUBELEMENT G9 ANTENNAS AND FEEDLINES

[4 Exam Questions–4 Groups]

Antennas & Feedlines 1

SUBELEMENT G9 ANTENNAS AND FEEDLINES

[4 Exam Questions–4 Groups]

G9A - Antenna feed lines; characteristic impedance, and attenuation; SWR calculation,

measurement and effects; matching networks

G9B - Basic antennasG9C - Directional antennasG9D - Specialized antennas

G9 - Antennas 3

FeedlineFeedliness

G9 - Antennas 4

Standing Waves

G9A01 - Which of the following factors determine the characteristic impedance of a parallel conductor

antenna feed line?A. The distance between the centers of the conductors and the radius of the conductorsB. The distance between the centers of the conductors and the length of the lineC. The radius of the conductors and the frequency of the signalD. The frequency of the signal and the length of the line

5Antennas & Feedlines

G9A01 - Which of the following factors determine the characteristic impedance of a parallel conductor

antenna feed line?A. The distance between the centers of A. The distance between the centers of the conductors and the radius of the the conductors and the radius of the conductorsconductorsB. The distance between the centers of the conductors and the length of the lineC. The radius of the conductors and the frequency of the signalD. The frequency of the signal and the length of the line


G9A02 - What are the typical characteristic impedances of coaxial cables used for antenna feed lines at

amateur stations?

A. 25 and 30 ohmsB. 50 and 75 ohmsC. 80 and 100 ohmsD. 500 and 750 ohms


G9A02 - 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 ohmsB. 50 and 75 ohmsC. 80 and 100 ohmsD. 500 and 750 ohms


G9A03 - What is the characteristic impedance of flat ribbon TV type

twinlead?

A. 50 ohmsB. 75 ohmsC. 100 ohmsD. 300 ohms


G9A03 - What is the characteristic impedance of flat ribbon TV type

twinlead?

A. 50 ohmsB. 75 ohmsC. 100 ohms

D. 300 ohmsD. 300 ohms


G9A04 - What might cause reflected power at the point where a

feed line connects to an antenna?

A. Operating an antenna at its resonant frequencyB. Using more transmitter power than the antenna can handleC. A difference between feed line impedance and antenna feed point impedanceD. Feeding the antenna with unbalanced feed line


G9A04 - What might cause reflected power at the point where a

feed line connects to an antenna?

A. Operating an antenna at its resonant frequencyB. Using more transmitter power than the antenna can handle

C. A difference between feed line C. A difference between feed line impedance and antenna feed point impedance and antenna feed point impedanceimpedanceD. Feeding the antenna with unbalanced feed line


G9A05 - How does the attenuation of coaxial cable change as the

frequency of the signal it is carrying increases?

A. Attenuation is independent of frequencyB. Attenuation increasesC. Attenuation decreasesD. Attenutation reaches a maximum at approximately 18 MHz


G9 - Antennas 14

Coax Cable Signal Loss (Attenuation) in dB per 100ft

Loss RG-174 RG-58 RG-8X RG-213 RG-6 RG-11 9913 LMR-400

1MHz 1.9dB 0.4dB 0.5dB 0.2dB 0.2dB 0.2dB 0.2dB 0.3dB








1GHz 32.0dB 21.5dB 13.5dB 8.3dB 6.1dB 5.6dB 4.5dB 4.1dB

Imped 50ohm 50ohm 50ohm 50ohm 75ohm 75ohm 50ohm 50ohm

G9A05 - 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 increasesB. Attenuation increasesC. Attenuation decreasesD. Attenutation reaches a maximum at approximately 18 MHz


G9A06 - In what units is RF feed line loss usually expressed?

A. Ohms per 1000 feetB. Decibels per 1000 feetC. Ohms per 100 feetD. Decibels per 100 feet


G9A06 - In what units is RF feed line loss usually expressed?

A. Ohms per 1000 feetB. Decibels per 1000 feetC. Ohms per 100 feet

D. Decibels per 100 feetD. Decibels per 100 feet


G9A07 - What must be done to prevent standing waves on an

antenna feed line?A. The antenna feed point must be at DC ground potentialB. The feed line must be cut to a length equal to an odd number of electrical quarter wavelengths C. The feed line must be cut to a length equal to an even number of physical half wavelengths D. The antenna feed point impedance must be matched to the characteristic impedance of the feed line


G9A07 - What must be done to prevent standing waves on an

antenna feed line?A. The antenna feed point must be at DC ground potentialB. The feed line must be cut to a length equal to an odd number of electrical quarter wavelengths C. The feed line must be cut to a length equal to an even number of physical half wavelengths

D. The antenna feed point impedance D. The antenna feed point impedance must be matched to the must be matched to the characteristic impedance of the feed characteristic impedance of the feed lineline


G9A08 - If the SWR on an antenna feed line is 5 to 1, and a matching network at

the transmitter end of the feed line is adjusted to 1 to 1 SWR, what is the

resulting SWR on the feed line?

A. 1 to 1B. 5 to 1C. Between 1 to 1 and 5 to 1 depending on the characteristic impedance of the lineD. Between 1 to 1 and 5 to 1 depending on the reflected power at the transmitter


G9A08 - If the SWR on an antenna feed line is 5 to 1, and a matching network at

the transmitter end of the feed line is adjusted to 1 to 1 SWR, what is the

resulting SWR on the feed line?

A. 1 to 1

B. 5 to 1B. 5 to 1C. Between 1 to 1 and 5 to 1 depending on the characteristic impedance of the lineD. Between 1 to 1 and 5 to 1 depending on the reflected power at the transmitter


G9A09 - What standing wave ratio will result when connecting a 50

ohm feed line to a non-reactive load having 200 ohm impedance?

A. 4:1B. 1:4C. 2:1D. 1:2




A. 4:1A. 4:1B. 1:4C. 2:1D. 1:2


200 / 50 = 4 to 1 or 4:14 to 1 or 4:1



A. 2:1B. 50:1C. 1:5D. 5:1




A. 2:1B. 50:1C. 1:5

D. 5:1D. 5:1


50 / 10 = 50 / 10 = 5 to 1 or 5:15 to 1 or 5:1

G9A11 - What standing wave ratio will result when connecting a 50 ohm feed line to a non-reactive load having 50

ohm impedance?

A. 2:1B. 1:1C. 50:50D. 0:0


G9A11 - What standing wave ratio will result when connecting a 50 ohm feed line to a non-reactive load having 50

ohm impedance?

A. 2:1

B. 1:1B. 1:1C. 50:50D. 0:0


50 / 50 = 50 / 50 = 1 to 1 or 1:11 to 1 or 1:1



A. 2:1B. 2.5:1C. 1.25:1D. You cannot determine SWR from impedance values




A. 2:1A. 2:1B. 2.5:1C. 1.25:1D. You cannot determine SWR from impedance values


Larger number always firstLarger number always first50 / 25 = 50 / 25 = 2 to 2 or 2:12 to 2 or 2:1


ohm feed line to an antenna that has a purely resistive 300 ohm feed

point impedance?

A. 1.5:1B. 3:1C. 6:1D. You cannot determine SWR from impedance values



ohm feed line to an antenna that has a purely resistive 300 ohm feed

point impedance?

A. 1.5:1B. 3:1

C. 6:1C. 6:1D. You cannot determine SWR from impedance values


300 / 50 = 300 / 50 = 6 to 1 or 6:16 to 1 or 6:1

G9A14 - What is the interaction between high standing wave ratio ( SWR ) and transmission line loss?

A. There is no interaction between transmission line loss and SWRB. If a transmission line is lossy, high SWR will increase the loss C. High SWR makes it difficult to measure transmission line lossD. High SWR reduces the relative effect of transmission line loss


G9A14 - 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 B. If a transmission line is lossy, high SWR will increase the loss SWR will increase the loss C. High SWR makes it difficult to measure transmission line lossD. High SWR reduces the relative effect of transmission line loss


G9A15 - 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 lowB. The higher the transmission line loss, the more the SWR will read artificially highC. The higher the transmission line loss, the more accurate the SWR measurement will beD. Transmission line loss does not affect the SWR measurement


G9A15 - What is the effect of transmission line loss on SWR measured

at the input to the line?

A. The higher the transmission line A. The higher the transmission line loss, the more the SWR will read loss, the more the SWR will read artificially lowartificially lowB. The higher the transmission line loss, the more the SWR will read artificially highC. The higher the transmission line loss, the more accurate the SWR measurement will beD. Transmission line loss does not affect the SWR measurement


G9B - Basic antennas


G9B01 - What is one disadvantage of a directly fed random-wire HF

antenna?

A. It must be longer than 1 wavelength B. You may experience RF burns when touching metal objects in your station C. It produces only vertically polarized radiationD. It is more effective on the lower HF bands than on the higher bands


G9B01 - What is one disadvantage of a directly fed random-wire HF

antenna?

A. It must be longer than 1 wavelength

B. You may experience RF burns B. You may experience RF burns when touching metal objects in your when touching metal objects in your station station C. It produces only vertically polarized radiationD. It is more effective on the lower HF bands than on the higher bands


G9 - Antennas 39

Vertical Antennas(Quarter Wavelength Vertical)

Ground Plane

Ground Plane

Ground

Marconi

Radials

Wavelength (meters) = Wavelength (meters) = 300 300 F (MHz)F (MHz)

¼¼λλ vertical length (inches) = Wavelength / 4 x 39 vertical length (inches) = Wavelength / 4 x 39

Quarter wavelength

Meters to inches

G9 - Antennas 40

Vertical Antenna

Standard ¼ wave vertical has a feedpoint impedance of ~35 ohms

Sloping ground radials downward raises feedpoint impedance

G9B02 - Which of the following is a common way to adjust the feed

point impedance of a quarter wave ground plane vertical antenna to be

approximately 50 ohms?

A. Slope the radials upwardB. Slope the radials downwardC. Lengthen the radialsD. Shorten the radials


G9B02 - Which of the following is a common way to adjust the feed

point impedance of a quarter wave ground plane vertical antenna to be

approximately 50 ohms?

A. Slope the radials upward

B. Slope the radials downwardB. Slope the radials downwardC. Lengthen the radialsD. Shorten the radials


G9B03 - What happens to the feed point impedance of a ground plane

antenna when its radials are changed from horizontal to sloping

downward?A. It decreasesB. It increasesC. It stays the sameD. It reaches a maximum at an angle of 45 degrees


G9B03 - What happens to the feed point impedance of a ground plane

antenna when its radials are changed from horizontal to sloping

downward?A. It decreases

B. It increasesC. It stays the sameD. It reaches a maximum at an angle of 45 degrees


G9 - Antennas 45

½ λ Dipole Radiation

Radiation pattern for a dipole placed ½ λabove ground looking down from above the antenna.

Looks like a doughnut around the wire in 3D space.

Pattern distorts to omnidirectional when placed low to the ground.

G9B04 - 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 antennaB. It is a figure-eight off both ends of the antennaC. 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


G9B04 - 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 A. It is a figure-eight at right angles to the antennathe antennaB. It is a figure-eight off both ends of the antennaC. 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


G9B05 - 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 unpredictableB. Antenna height has no effect on the patternC. If the antenna is less than 1/2 wavelength high, the azimuthal pattern is almost omnidirectionalD. If the antenna is less than 1/2 wavelength high, radiation off the ends of the wire is eliminated



G9B05 - How does antenna height affect the horizontal ( azimuthal ) radiation pattern of a horizontal

dipole HF antenna?

AntennaHeightAbove Ground

G9B05 - 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 unpredictableB. Antenna height has no effect on the pattern

C. If the antenna is less than 1/2 C. If the antenna is less than 1/2 wavelength high, the azimuthal wavelength high, the azimuthal pattern is almost omnidirectionalpattern is almost omnidirectionalD. If the antenna is less than 1/2 wavelength high, radiation off the ends of the wire is eliminated


G9B06 - Where should the radial wires of a ground-mounted vertical antenna

system be placed?

A. As high as possible above the groundB. Parallel to the antenna elementC. On the surface of the Earth or buried a few inches below the groundD. At the center of the antenna


G9B06 - Where should the radial wires of a ground-mounted vertical antenna

system be placed?

A. As high as possible above the groundB. Parallel to the antenna element

C. On the surface of the Earth C. On the surface of the Earth or buried a few inches below or buried a few inches below the groundthe groundD. At the center of the antenna


Ground Radials


G9B07 - How does the feed point impedance of a 1/2 wave dipole antenna change as the antenna is lowered below

1/4 wave above ground?

A. It steadily increasesB. It steadily decreasesC. It peaks at about 1/8 wavelength above groundD. It is unaffected by the height above ground


G9B07 - How does the feed point impedance of a 1/2 wave dipole antenna change as the antenna is lowered below

1/4 wave above ground?

A. It steadily increases

B. It steadily decreasesB. It steadily decreasesC. It peaks at about 1/8 wavelength above groundD. It is unaffected by the height above ground


G9B08 - How does the feed point impedance of a 1/2 wave dipole change

as the feed point is moved from the center toward the ends?

A. It steadily increasesB. It steadily decreasesC. It peaks at about 1/8 wavelength from the endD. It is unaffected by the location of the feed point


G9B08 - How does the feed point impedance of a 1/2 wave dipole change

as the feed point is moved from the center toward the ends?

A. It steadily increasesA. It steadily increasesB. It steadily decreasesC. It peaks at about 1/8 wavelength from the endD. It is unaffected by the location of the feed point


G9B09 - Which of the following is an advantage of a horizontally polarized as

compared to a vertically polarized HF antenna?

A. Lower ground reflection losses B. Lower feed point impedanceC. Shorter RadialsD. Lower radiation resistance


G9B09 - Which of the following is an advantage of a horizontally polarized as

compared to a vertically polarized HF antenna?

A. Lower ground reflection A. Lower ground reflection losseslosses

B. Lower feed point impedanceC. Shorter RadialsD. Lower radiation resistance


G9B10 - What is the approximate length for a 1/2 wave dipole antenna

cut for 14.250 MHz?

A. 8 feetB. 16 feetC. 24 feetD. 32 feet


Electrical Principles 2010 61

Meters Calculations

• Half wave• 21.0526 / 2 =21.0526 / 2 =• 10.5263 m10.5263 m• Meters to inches• 10.5263 x 39.37 10.5263 x 39.37 • = 414.42 inch= 414.42 inch• Inches to feet• 414.42 / 12414.42 / 12• = 34.535 feet= 34.535 feet• Velosity factor• 34.535 x .95• =32.8 feet

300300

f = f = 14.214.2

55

mm

meters = 300/14.250 = 21.0526 m


cut for 14.250 MHz?

A. 8 feetB. 16 feetC. 24 feet

D. 32 feet



cut for 3.550 MHz?




Meters Calculations

• Half wave• 84.507 / 2 =84.507 / 2 =• 42.2535 m42.2535 m• Meters to inches• 42.2535 x 39.37 42.2535 x 39.37 • = 1663.52 inch= 1663.52 inch• Inches to feet• 1663.52 / 121663.52 / 12• = 138.627 feet= 138.627 feet• Velosity factor• 138.627 x .95138.627 x .95• =131.7 feet

300300

f = f = 3.553.55

00

mm

meters = 300/3.550 = 84.507 mmeters = 300/3.550 = 84.507 m


cut for 3.550 MHz?

A. 42 feetB. 84 feet

C. 131 feetC. 131 feetD. 263 feet


G9B12 - What is the approximate length for a 1/4 wave vertical

antenna cut for 28.5 MHz?




Meters Calculations

• Quarter wave• 10.5263 / 4 =10.5263 / 4 =• 2.63 m2.63 m• Meters to inches• 2.63 x 39.37 2.63 x 39.37 • = 103.605 inch= 103.605 inch• Inches to feet• 103.605 / 12103.605 / 12• = 8.63 feet= 8.63 feet• Velosity factor• 8.63 x .958.63 x .95• =8.2 feet

300300

f = f = 28.5028.50

00

mm

meters = 300/28.5 = 10.5263 mmeters = 300/28.5 = 10.5263 m

G9B12 - What is the approximate length for a 1/4 wave vertical

antenna cut for 28.5 MHz?

A. 8 feetA. 8 feetB. 11 feetC. 16 feetD. 21 feet


G9C - Directional antennas


G9 - Antennas 70

Beam Antennas(Yagi Antenna)

GainGain

BoomBoom

Feed

line

Feed

line

Reflect

or

Reflect

or

Dir

ect

oD

irect

orr

Dri

ven

D

riven

Ele

men

tEle

men

t

The reflectorThe reflectoracts like a acts like a

mirrormirror

The directorThe directoracts like aacts like a

lenslens

G9 - Antennas 71

Yagi Radiation Pattern

The yagi antenna focuses RF energy in one direction, giving the appearance ofgetting “free power.”

This free power or Effective Radiated Power (ERP) can be expressed as antenna Gain in Decibels (dB) over a dipole (dBd) or isotropic resonator (dBi).

G9 - Antennas 72

Quad antenna

G9 - Antennas 73

Delta Loop

G9C01 - Which of the following would increase the bandwidth of a

Yagi antenna?

A. Larger diameter elementsB. Closer element spacingC. Loading coils in series with the elementD. Tapered-diameter elements


G9C01 - Which of the following would increase the bandwidth of a

Yagi antenna?

A. Larger diameter elementsA. Larger diameter elementsB. Closer element spacingC. Loading coils in series with the elementD. Tapered-diameter elements


G9C02 - What is the approximate length of the driven element of a

Yagi antenna?

A. 1/4 wavelengthB. 1/2 wavelengthC. 3/4 wavelengthD. 1 wavelength


G9C02 - What is the approximate length of the driven element of a

Yagi antenna?

A. 1/4 wavelength

B. 1/2 wavelengthB. 1/2 wavelengthC. 3/4 wavelengthD. 1 wavelength


G9C03 - Which statement about a three-element, single-band Yagi

antenna is true?

A. The reflector is normally the shortest elementB. The director is normally the shortest elementC. The driven element is the longest elementD. Low feed point impedance increases bandwidth



antenna is true?

A. The reflector is normally the shortest element

B. The director is normally the shortest B. The director is normally the shortest elementelementC. The driven element is the longest elementD. Low feed point impedance increases bandwidth



antenna is true?A. The reflector is normally the longest elementB. The director is normally the longest element C. The reflector is normally the shortest elementD. All of the elements must be the same length



antenna is true?A. The reflector is normally the longest A. The reflector is normally the longest elementelementB. The director is normally the longest element C. The reflector is normally the shortest elementD. All of the elements must be the same length


20m Yagi20m Yagi

20 Meter Yagi


G9C05 - How does increasing boom length and adding directors affect a

Yagi antenna?

A. Gain increasesB. Beamwidth increasesC. Front to back ratio decreases D. Front to side ratio decreases


G9C05 - How does increasing boom length and adding directors affect a

Yagi antenna?

A. Gain increasesA. Gain increasesB. Beamwidth increasesC. Front to back ratio decreases D. Front to side ratio decreases


G9C06 - 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? A. The driven element must be fed with a balun transformerB. There must be an open circuit in the driven element at the point opposite the feed pointC. The reflector element must be approximately 5 percent shorter than the driven elementD. The reflector element must be approximately 5 percent longer than the driven element


G9C06 - 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? A. The driven element must be fed with a balun transformerB. There must be an open circuit in the driven element at the point opposite the feed pointC. The reflector element must be approximately 5 percent shorter than the driven element

D. The reflector element must be D. The reflector element must be approximately 5 percent longer than approximately 5 percent longer than the driven elementthe driven element


G9C07 - What does "front-to-back ratio" mean in reference to a Yagi

antenna?A. The number of directors versus the number of reflectorsB. The relative position of the driven element with respect to the reflectors and directorsC. The power radiated in the major radiation lobe compared to the power radiated in exactly the opposite directionD. The ratio of forward gain to dipole gain


G9C07 - What does "front-to-back ratio" mean in reference to a Yagi

antenna?A. The number of directors versus the number of reflectorsB. The relative position of the driven element with respect to the reflectors and directors

C. The power radiated in the major C. The power radiated in the major radiation lobe compared to the power radiation lobe compared to the power radiated in exactly the opposite radiated in exactly the opposite directiondirectionD. The ratio of forward gain to dipole gain


Antenna Radiation Pattern Front to Back Ratio’s


G9C08 - What is meant by the "main lobe" of a directive antenna?

A. The magnitude of the maximum vertical angle of radiationB. The point of maximum current in a radiating antenna elementC. The maximum voltage standing wave point on a radiating elementD. The direction of maximum radiated field strength from the antenna


G9C08 - What is meant by the "main lobe" of a directive antenna?

A. The magnitude of the maximum vertical angle of radiationB. The point of maximum current in a radiating antenna elementC. The maximum voltage standing wave point on a radiating element

D. The direction of maximum radiated D. The direction of maximum radiated field strength from the antennafield strength from the antenna


Antenna Radiation Patterns


G9C09 - How does the gain of two 3-element horizontally polarized Yagi

antennas spaced vertically 1/2 wavelength apart typically compare to

the gain of a single 3-element Yagi?

A. Approximately 1.5 dB higherB. Approximately 3 dB higherC. Approximately 6 dB higherD. Approximately 9 dB higher


G9C09 - How does the gain of two 3-element horizontally polarized 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. Approximately 3 dB higherC. Approximately 6 dB higherD. Approximately 9 dB higher


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?

A. The physical length of the boomB. The number of elements on the boomC. The spacing of each element along the boomD. All of these choices are correct


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?

A. The physical length of the boomB. The number of elements on the boomC. The spacing of each element along the boom

D. All of these choices are correctD. All of these choices are correct


G9C11 - What is the purpose of a gamma match used with Yagi

antennas?

A. To match the relatively low feed point impedance to 50 ohmsB. To match the relatively high feed point impedance to 50 ohmsC. To increase the front-to-back ratioD. To increase the main lobe gain


G9C11 - What is the purpose of a gamma match used with Yagi

antennas?

A. To match the relatively low feed A. To match the relatively low feed point impedance to 50 ohmspoint impedance to 50 ohmsB. To match the relatively high feed point impedance to 50 ohmsC. To increase the front-to-back ratioD. To increase the main lobe gain


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?

A. It does not require that the elements be insulated from the boomB. It does not require any inductors or capacitorsC. It is useful for matching multiband antennasD. All of these choices are correct


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?

A. It does not require that the A. It does not require that the elements be insulated from the boomelements be insulated from the boomB. It does not require any inductors or capacitorsC. It is useful for matching multiband antennasD. All of these choices are correct


G9C13 - Approximately how long is each side of the driven element of a

quad antenna?

A. 1/4 wavelengthB. 1/2 wavelengthC. 3/4 wavelengthD. 1 wavelength


G9C13 - Approximately how long is each side of the driven element of a

quad antenna?

A. 1/4 wavelengthA. 1/4 wavelengthB. 1/2 wavelengthC. 3/4 wavelengthD. 1 wavelength


G9C14 - 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 muchB. About the sameC. About 1.5 times as muchD. About twice as much


G9C14 - 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 sameB. About the sameC. About 1.5 times as muchD. About twice as much


G9C15 - Approximately how long is each side of the reflector element of

a quad antenna?

A. Slightly less than 1/4 wavelengthB. Slightly more than 1/4 wavelengthC. Slightly less than 1/2 wavelengthD. Slightly more than 1/2 wavelength


G9C15 - 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 B. Slightly more than 1/4 wavelengthwavelengthC. Slightly less than 1/2 wavelengthD. Slightly more than 1/2 wavelength


G9C16 - How does the gain of a two-element delta-loop beam compare to the gain of a two-

element quad antenna?

A. 3 dB higherB. 3 dB lowerC. 2.54 dB higherD. About the same


G9C16 - How does the gain of a two-element delta-loop beam compare to the gain of a two-

element quad antenna?

A. 3 dB higherB. 3 dB lowerC. 2.54 dB higher

D. About the sameD. About the same


G9C17 - Approximately how long is each leg of a symmetrical delta-loop

antenna?

A. 1/4 wavelengthB. 1/3 wavelengthC. 1/2 wavelengthD. 2/3 wavelength


G9C17 - Approximately how long is each leg of a symmetrical delta-loop

antenna?

A. 1/4 wavelength

B. 1/3 wavelengthB. 1/3 wavelengthC. 1/2 wavelengthD. 2/3 wavelength


G9C18 - What happens when the feed point of a quad antenna of any shape is moved from the midpoint of the top or bottom to the midpoint of

either side?A. The polarization of the radiated signal changes from horizontal to verticalB. The polarization of the radiated signal changes from vertical to horizontalC. There is no change in polarizationD. The radiated signal becomes circularly polarized


G9C18 - What happens when the feed point of a quad antenna of any shape is moved from the midpoint of the top or bottom to the midpoint of

either side?A. The polarization of the radiated A. The polarization of the radiated signal changes from horizontal to signal changes from horizontal to verticalverticalB. The polarization of the radiated signal changes from vertical to horizontalC. There is no change in polarizationD. The radiated signal becomes circularly polarized


G9C19 - 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 then dBd gain figuresB. dBi gain figures are 2.15 dB higher than dBd gain figuresC. dBi gain figures are the same as the square root of dBd gain figures multiplied by 2.15D. dBi gain figures are the reciprocal of dBd gain figures + 2.15 dB


G9C19 - 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 then dBd gain figures

B. dBi gain figures are 2.15 dB B. dBi gain figures are 2.15 dB higher than dBd gain figureshigher than dBd gain figuresC. dBi gain figures are the same as the square root of dBd gain figures multiplied by 2.15D. dBi gain figures are the reciprocal of dBd gain figures + 2.15 dB


G9C20 - 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 antennaB. dBi refers to an ionospheric reflecting antenna, dBd refers to a dissipative antennaC. dBi refers to an inverted-vee antenna, dBd refers to a downward reflecting antennaD. dBi refers to an isometric antenna, dBd refers to a discone antenna


G9C20 - What is meant by the terms dBi and dBd when referring

to antenna gain?A. dBi refers to an isotropic antenna, A. dBi refers to an isotropic antenna, dBd refers to a dipole antennadBd refers to a dipole antennaB. dBi refers to an ionospheric reflecting antenna, dBd refers to a dissipative antennaC. dBi refers to an inverted-vee antenna, dBd refers to a downward reflecting antennaD. dBi refers to an isometric antenna, dBd refers to a discone antenna


G9D - Specialized antennas


G9D01 - What does the term NVIS mean as related to antennas?

A. Nearly Vertical Inductance SystemB. Non-Varying Indicated SWRC. Non-Varying Impedance SmoothingD. Near Vertical Incidence sky-wave


G9D01 - What does the term NVIS mean as related to antennas?

A. Nearly Vertical Inductance SystemB. Non-Varying Indicated SWRC. Non-Varying Impedance Smoothing

D. Near Vertical Incidence sky-D. Near Vertical Incidence sky-wavewave


G9D02 - 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 kilometersB. High vertical angle radiation for working stations within a radius of a few hundred kilometersC. High forward gainD. All of these choices are correct


G9D02 - 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 kilometers

B. High vertical angle B. High vertical angle radiation for working stations radiation for working stations within a radius of a few within a radius of a few hundred kilometershundred kilometersC. High forward gainD. All of these choices are correct


G9D03 - At what height above ground is an NVIS antenna typically

installed?

A. As close to 1/2 wavelength as possibleB. As close to one wavelength as possibleC. Height is not critical as long as it is significantly more than 1/2 wavelengthD. Between 1/10 and 1/4 wavelength


G9D03 - At what height above ground is an NVIS antenna typically

installed?

A. As close to 1/2 wavelength as possibleB. As close to one wavelength as possibleC. Height is not critical as long as it is significantly more than 1/2 wavelength

D. Between 1/10 and 1/4 wavelengthD. Between 1/10 and 1/4 wavelength


G9D04 - What is the primary purpose of antenna traps?

A. To permit multiband operationB. To notch spurious frequenciesC. To provide balanced feed point impedanceD. To prevent out of band operation


G9D04 - What is the primary purpose of antenna traps?

A. To permit multiband A. To permit multiband operationoperationB. To notch spurious frequenciesC. To provide balanced feed point impedanceD. To prevent out of band operation


Antenna Traps


G9D05 - What is an advantage of vertical stacking of horizontally

polarized Yagi antennas?

A. It allows quick selection of vertical or horizontal polarizationB. It allows simultaneous vertical and horizontal polarizationC. It narrows the main lobe in azimuthD. It narrows the main lobe in elevation


G9D05 - What is an advantage of vertical stacking of horizontally

polarized Yagi antennas?

A. It allows quick selection of vertical or horizontal polarizationB. It allows simultaneous vertical and horizontal polarizationC. It narrows the main lobe in azimuth

D. It narrows the main lobe in D. It narrows the main lobe in elevationelevation


G9D06 - Which of the following is an advantage of a log periodic

antenna?

A. Wide bandwidthB. Higher gain per element than a Yagi antennaC. Harmonic suppressionD. Polarization diversity


G9D06 - Which of the following is an advantage of a log periodic

antenna?

A. Wide bandwidthA. Wide bandwidthB. Higher gain per element than a Yagi antennaC. Harmonic suppressionD. Polarization diversity


G9D07 - 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 otherB. Impedance varies periodically as a function of frequencyC. Gain varies logarithmically as a function of frequencyD. SWR varies periodically as a function of boom length


G9D07 - Which of the following describes a log periodic antenna?

A. Length and spacing of the elements A. Length and spacing of the elements increase logarithmically from one end increase logarithmically from one end of the boom to the otherof the boom to the otherB. Impedance varies periodically as a function of frequencyC. Gain varies logarithmically as a function of frequencyD. SWR varies periodically as a function of boom length


G9D08 - Why is a Beverage antenna not used for transmitting?

A. Its impedance is too low for effective matchingB. It has high losses compared to other types of antennasC. It has poor directivityD. All of these choices are correct


Redneck Beverage Antenna


G9D08 - 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 B. It has high losses compared to other types of antennasother types of antennasC. It has poor directivityD. All of these choices are correct


G9D09 - Which of the following is an application for a Beverage

antenna?

A. Directional transmitting for low HF bandsB. Directional receiving for low HF bandsC. Portable direction finding at higher HF frequenciesD. Portable direction finding at lower HF frequencies


G9D09 - Which of the following is an application for a Beverage

antenna?

A. Directional transmitting for low HF bands

B. Directional receiving for low HF B. Directional receiving for low HF bandsbandsC. Portable direction finding at higher HF frequenciesD. Portable direction finding at lower HF frequencies


G9D10 - Which of the following describes a Beverage antenna?

A. A vertical antennaB. A broad-band mobile antenna C. A helical antenna for space receptionD. A very long and low directional receiving antenna


G9D10 - Which of the following describes a Beverage antenna?

A. A vertical antennaB. A broad-band mobile antenna C. A helical antenna for space reception

D. A very long and low D. A very long and low directional receiving antennadirectional receiving antenna


G9D11 - Which of the following is a disadvantage of multiband

antennas?

A. They present low impedance on all design frequenciesB. They must be used with an antenna tunerC. They must be fed with open wire lineD. They have poor harmonic rejection


G9D11 - Which of the following is a disadvantage of multiband

antennas?

A. They present low impedance on all design frequenciesB. They must be used with an antenna tunerC. They must be fed with open wire line

D. They have poor harmonic rejectionD. They have poor harmonic rejection


End OfSUBELEMENT G9

ANTENNAS AND FEEDLINES

subelement g9 antennas and feedlines [4 exam questions–4 groups] antennas & feedlines1

Documents

feed line impedance

unbalanced feed line

attenuation increasesc

attenuation decreasesd

reflected power

transmitter power

attenuation swr calculation

resonant frequencyb