007 - Feedlines - Matching and Antenna Systems Flashcards
A-007-001-001
For an antenna tuner of the “Transformer” type, which of the following statements is FALSE?
(a) The input is suitable for 50 ohm impedance
(b) The output is suitable for impedances from low to high
(c) The circuit is known as a transformer-type antenna tuner
(d) The circuit is known as a Pi-type antenna tuner
A-007-001-001
For an antenna tuner of the “Transformer” type, which of the following statements is FALSE?
(d) The circuit is known as a Pi-type antenna tuner
A-007-001-002
For an antenna tuner of the “Series” type, which of the following statements is false?
(a) The circuit is known as a Pi-type antenna tuner
(b) The circuit is known as a Series-type antenna tuner
(c) The output is suitable for impedances from low to high
(d) The input is suitable for impedance of 50 ohms
A-007-001-002
For an antenna tuner of the “Series” type, which of the following statements is false?
(a) The circuit is known as a Pi-type antenna tuner
A-007-001-003
For an antenna tuner of the “L” type, which of the following statements is false?
(a) The transmitter input is suitable for 50 ohms impedance
(b) The antenna output is high impedance
(c) The circuit is suitable for matching to a vertical ground plane antenna
(d) The circuit is known as an L-type antenna tuner
A-007-001-003
For an antenna tuner of the “L” type, which of the following statements is false?
(c) The circuit is suitable for matching to a vertical ground plane antenna
A-007-001-004
For an antenna tuner of the “Pi” type, which of the following statements is false?
(a) The circuit is a series-type antenna tuner
(b) The transmitter input is suitable for impedance of 50 ohms
(c) The antenna output is suitable for impedances from low to high
(d) The circuit is a Pi-type antenna tuner
A-007-001-004
For an antenna tuner of the “Pi” type, which of the following statements is false?
(a) The circuit is a series-type antenna tuner
A-007-001-005
What is a pi-network?
(a) An antenna matching network that is isolated from ground
(b) A network consisting of four inductors or four capacitors
(c) A network consisting of one inductor and two capacitors or two inductors and one capacitor
(d) A power incidence network
A-007-001-005
What is a pi-network?
(c) A network consisting of one inductor and two capacitors or two inductors and one capacitor
A-007-001-006
Which type of network offers the greatest transformation ratio?
(a) Chebyshev
(b) Butterworth
(c) L-network
(d) Pi-network
A-007-001-006
Which type of network offers the greatest transformation ratio?
(d) Pi-network
A-007-001-007
Why is an L-network of limited utility in impedance matching?
(a) It is thermally unstable
(b) It matches only a small impedance range
(c) It is prone to self-resonance
(d) It has limited power handling capability
A-007-001-007
Why is an L-network of limited utility in impedance matching?
(b) It matches only a small impedance range
A-007-001-008
How does a network transform one impedance to another?
(a) It produces transconductance to cancel the reactive part of an impedance
(b) It cancels the reactive part of an impedance and changes the resistive part
(c) It introduces negative resistance to cancel the resistive part of an impedance
(d) Network resistances substitute for load resistances
A-007-001-008
How does a network transform one impedance to another?
(b) It cancels the reactive part of an impedance and changes the resistive part
A-007-001-009
What advantage does a pi-L network have over a pi-network for impedance matching between a vacuum tube linear amplifier and a multiband antenna?
(a) Greater harmonic suppression
(b) Higher efficiency
(c) Lower losses
(d) Greater transformation range
A-007-001-009
What advantage does a pi-L network have over a pi-network for impedance matching between a vacuum tube linear amplifier and a multiband antenna?
(a) Greater harmonic suppression
A-007-001-010
Which type of network provides the greatest harmonic suppression?
(a) Inverse pi-network
(b) Pi-network
(c) Pi-L network
(d) L-network
A-007-001-010
Which type of network provides the greatest harmonic suppression?
(c) Pi-L network
A-007-001-011
A Smith Chart is useful:
(a) because it simplifies mathematical operations
(b) only to solve matching and transmission line problems
(c) to solve problems in direct current circuits
(d) because it only works with complex numbers
A-007-001-011
A Smith Chart is useful:
(a) because it simplifies mathematical operations
A-007-002-001
What kind of impedance does a quarter wavelength transmission line present to the source when the line is shorted at the far end?
(a) The same as the characteristic impedance of the transmission line
(b) The same as the output impedance of the source
(c) A very high impedance
(d) A very low impedance
A-007-002-001
What kind of impedance does a quarter wavelength transmission line present to the source when the line is shorted at the far end?
(c) A very high impedance
A-007-002-002
What kind of impedance does a quarter wavelength transmission line present to the source if the line is open at the far end?
(a) A very low impedance
(b) A very high impedance
(c) The same as the output impedance of the source
(d) The same as the characteristic impedance of the transmission line
A-007-002-002
What kind of impedance does a quarter wavelength transmission line present to the source if the line is open at the far end?
(a) A very low impedance
A-007-002-003
What kind of impedance does a half wavelength transmission line present to the source when the line is open at the far end?
(a) The same as the characteristic impedance of the transmission line
(b) A very high impedance
(c) The same as the output impedance of the source
(d) A very low impedance
A-007-002-003
What kind of impedance does a half wavelength transmission line present to the source when the line is open at the far end?
(b) A very high impedance
A-007-002-004
What kind of impedance does a half wavelength transmission line present to the source when the line is shorted at the far end?
(a) A very high impedance
(b) The same as the characteristic impedance of the transmission line
(c) The same as the output impedance of the source
(d) A very low impedance
A-007-002-004
What kind of impedance does a half wavelength transmission line present to the source when the line is shorted at the far end?
(d) A very low impedance
A-007-002-005
What is the velocity factor of a transmission line?
(a) The velocity of the wave on the transmission line multiplied by the velocity of light in a vacuum
(b) The index of shielding for coaxial cable
(c) The velocity of the wave on the transmission line divided by the velocity of light
(d) The ratio of the characteristic impedance of the line to the terminating impedance
A-007-002-005
What is the velocity factor of a transmission line?
(c) The velocity of the wave on the transmission line divided by the velocity of light
A-007-002-006
What is the term for the ratio of the actual velocity at which a signal travels through a transmission line to the speed of light in a vacuum?
(a) Velocity factor
(b) Characteristic impedance
(c) Surge impedance
(d) Standing wave ratio
A-007-002-006
What is the term for the ratio of the actual velocity at which a signal travels through a transmission line to the speed of light in a vacuum?
(a) Velocity factor
A-007-002-007
What is a typical velocity factor for coaxial cable with polyethylene dielectric?
(a) 0.33
(b) 0.1
(c) 2.7
(d) 0.66
A-007-002-007
What is a typical velocity factor for coaxial cable with polyethylene dielectric?
(d) 0.66
A-007-002-008
What determines the velocity factor in a transmission line?
(a) The line length
(b) The centre conductor resistivity
(c) Dielectrics in the line
(d) The terminal impedance
A-007-002-008
What determines the velocity factor in a transmission line?
(c) Dielectrics in the line
A-007-002-009
Why is the physical length of a coaxial cable shorter than its electrical length?
(a) RF energy moves slower along the coaxial cable than in air
(b) The surge impedance is higher in the parallel transmission line
(c) Skin effect is less pronounced in the coaxial cable
(d) The characteristic impedance is higher in a parallel transmission line
A-007-002-009
Why is the physical length of a coaxial cable shorter than its electrical length?
(a) RF energy moves slower along the coaxial cable than in air
A-007-002-010
The reciprocal of the square root of the dielectric constant of the material used to separate the conductors in a transmission line gives the ____________ of the line:
(a) VSWR
(b) velocity factor
(c) impedance
(d) hermetic losses
A-007-002-010
The reciprocal of the square root of the dielectric constant of the material used to separate the conductors in a transmission line gives the ____________ of the line:
(b) velocity factor
A-007-002-011
The velocity factor of a transmission line is the:
(a) impedance of the line, e.g. 50 ohm, 75 ohm, etc.
(b) ratio of the velocity of propagation in the transmission line to the velocity of propagation in free space
(c) speed at which the signal travels in free space
(d) speed to which the standing waves are reflected back to the transmitter
A-007-002-011
The velocity factor of a transmission line is the:
(b) ratio of the velocity of propagation in the transmission line to the velocity of propagation in free space
A-007-003-001
What term describes a method used to match a high-impedance transmission line to a lower impedance antenna by connecting the line to the driven element in two places, spaced a fraction of a wavelength on each side of the driven element centre?
(a) The gamma match
(b) The omega match
(c) The T match
(d) The stub match
A-007-003-001
What term describes a method used to match a high-impedance transmission line to a lower impedance antenna by connecting the line to the driven element in two places, spaced a fraction of a wavelength on each side of the driven element centre?
(c) The T match
A-007-003-002
What term describes an unbalanced feed system in which the driven element of an antenna is fed both at the centre and a fraction of a wavelength to one side of centre?
(a) The omega match
(b) The stub match
(c) The T match
(d) The gamma match
A-007-003-002
What term describes an unbalanced feed system in which the driven element of an antenna is fed both at the centre and a fraction of a wavelength to one side of centre?
(d) The gamma match
A-007-003-003
What term describes a method of antenna impedance matching that uses a short section of transmission line connected to the antenna transmission line near the antenna and perpendicular to the transmission line?
(a) The omega match
(b) The delta match
(c) The stub match
(d) The gamma match
A-007-003-003
What term describes a method of antenna impedance matching that uses a short section of transmission line connected to the antenna transmission line near the antenna and perpendicular to the transmission line?
(c) The stub match
A-007-003-004
Assuming a velocity factor of 0.66 what would be the physical length of a typical coaxial stub that is electrically one quarter wavelength long at 14.1 MHz?
(a) 3.51 metres (11.5 feet)
(b) 20 metres (65.6 feet)
(c) 2.33 metres (7.64 feet)
(d) 0.25 metre (0.82 foot)
A-007-003-004
Assuming a velocity factor of 0.66 what would be the physical length of a typical coaxial stub that is electrically one quarter wavelength long at 14.1 MHz?
(a) 3.51 metres (11.5 feet)
A-007-003-005
The driven element of a Yagi antenna is connected to a coaxial transmission line. The coax braid is connected to the centre of the driven element and the centre conductor is connected to a variable capacitor in series with an adjustable mechanical arrangement on one side of the driven element. The type of matching is:
(a) gamma match
(b) lambda match
(c) T match
(d) zeta match
A-007-003-005
The driven element of a Yagi antenna is connected to a coaxial transmission line. The coax braid is connected to the centre of the driven element and the centre conductor is connected to a variable capacitor in series with an adjustable mechanical arrangement on one side of the driven element. The type of matching is:
(a) gamma match
A-007-003-006
A quarter-wave stub, for use at 15 MHz, is made from a coaxial cable having a velocity factor of 0.8. Its physical length will be:
(a) 4 m (13.1 ft)
(b) 12 m (39.4 ft)
(c) 8 m (26.2 ft)
(d) 7.5 m (24.6 ft)
A-007-003-006
A quarter-wave stub, for use at 15 MHz, is made from a coaxial cable having a velocity factor of 0.8. Its physical length will be:
(a) 4 m (13.1 ft)
A-007-003-007
The matching of a driven element with a single adjustable mechanical and capacitive arrangement is descriptive of:
(a) a “T” match
(b) an “omega” match
(c) a “gamma” match
(d) a “Y” match
A-007-003-007
The matching of a driven element with a single adjustable mechanical and capacitive arrangement is descriptive of:
(c) a “gamma” match
A-007-003-008
A Yagi antenna uses a gamma match. The coaxial braid connects to:
(a) the variable capacitor
(b) the centre of the driven element
(c) the adjustable gamma rod
(d) the centre of the reflector
A-007-003-008
A Yagi antenna uses a gamma match. The coaxial braid connects to:
(b) the centre of the driven element
A-007-003-009
A Yagi antenna uses a gamma match. The centre of the driven element connects to:
(a) the coaxial line centre conductor
(b) the adjustable gamma rod
(c) a variable capacitor
(d) the coaxial line braid
A-007-003-009
A Yagi antenna uses a gamma match. The centre of the driven element connects to:
(d) the coaxial line braid
A-007-003-010
A Yagi antenna uses a gamma match. The adjustable gamma rod connects to:
(a) the coaxial line centre conductor
(b) the variable capacitor
(c) an adjustable point on the reflector
(d) the centre of the driven element
A-007-003-010
A Yagi antenna uses a gamma match. The adjustable gamma rod connects to:
(b) the variable capacitor
A-007-003-011
A Yagi antenna uses a gamma match. The variable capacitor connects to the:
(a) an adjustable point on the director
(b) center of the driven element
(c) coaxial line braid
(d) adjustable gamma rod
A-007-003-011
A Yagi antenna uses a gamma match. The variable capacitor connects to the:
(d) adjustable gamma rod
A-007-004-001
In a half-wave dipole, the distribution of _______ is highest at each end.
(a) current
(b) inductance
(c) capacitance
(d) voltage
A-007-004-001
In a half-wave dipole, the distribution of _______ is highest at each end.
(d) voltage
A-007-004-002
In a half-wave dipole, the distribution of _______ is lowest at each end.
(a) voltage
(b) inductance
(c) current
(d) capacitance
A-007-004-002
In a half-wave dipole, the distribution of _______ is lowest at each end.
(c) current
A-007-004-003
The feed point in a centre-fed half-wave antenna is at the point of:
(a) minimum current
(b) maximum current
(c) minimum voltage and current
(d) maximum voltage
A-007-004-003
The feed point in a centre-fed half-wave antenna is at the point of:
(b) maximum current
A-007-004-004
In a half-wave dipole, the lowest distribution of _________ occurs at the middle.
(a) capacity
(b) inductance
(c) current
(d) voltage
A-007-004-004
In a half-wave dipole, the lowest distribution of _________ occurs at the middle.
(d) voltage
A-007-004-005
In a half-wave dipole, the highest distribution of ________ occurs at the middle.
(a) inductance
(b) voltage
(c) capacity
(d) current
A-007-004-005
In a half-wave dipole, the highest distribution of ________ occurs at the middle.
(d) current
A-007-004-006
A half-wave dipole antenna is normally fed at the point where:
(a) the current is maximum
(b) the voltage is maximum
(c) the resistance is maximum
(d) the antenna is resonant
A-007-004-006
A half-wave dipole antenna is normally fed at the point where:
(a) the current is maximum
A-007-004-007
At the ends of a half-wave dipole:
(a) voltage and current are both high
(b) voltage and current are both low
(c) voltage is high and current is low
(d) voltage is low and current is high
A-007-004-007
At the ends of a half-wave dipole:
(c) voltage is high and current is low
A-007-004-008
The impedance of a half-wave antenna at its centre is low, because at this point:
(a) voltage and current are both high
(b) voltage and current are both low
(c) voltage is high and current is low
(d) voltage is low and current is high
A-007-004-008
The impedance of a half-wave antenna at its centre is low, because at this point:
(d) voltage is low and current is high
A-007-004-009
In a half-wave dipole, where does minimum voltage occur?
(a) At the right end
(b) It is equal at all points
(c) Both ends
(d) The centre
A-007-004-009
In a half-wave dipole, where does minimum voltage occur?
(d) The centre
A-007-004-010
In a half-wave dipole, where does the minimum current occur?
(a) At the centre
(b) At both ends
(c) It is equal at all points
(d) At the right end
A-007-004-010
In a half-wave dipole, where does the minimum current occur?
(b) At both ends
A-007-004-011
In a half-wave dipole, where does the minimum impedance occur?
(a) It is the same at all points
(b) At the centre
(c) At the right end
(d) At both ends
A-007-004-011
In a half-wave dipole, where does the minimum impedance occur?
(b) At the centre
A-007-005-001
What is meant by circularly polarized electromagnetic waves?
(a) Waves with an electric field bent into circular shape
(b) Waves with a rotating electric field
(c) Waves that circle the earth
(d) Waves produced by a circular loop antenna
A-007-005-001
What is meant by circularly polarized electromagnetic waves?
(b) Waves with a rotating electric field
A-007-005-002
What type of polarization is produced by crossed dipoles fed 90 degrees out of phase?
(a) Cross-polarization
(b) Perpendicular polarization
(c) Circular polarization
(d) None of the other answers, the two fields cancel out
A-007-005-002
What type of polarization is produced by crossed dipoles fed 90 degrees out of phase?
(c) Circular polarization
A-007-005-003
Which of these antennas does not produce circular polarization?
(a) Crossed dipoles fed 90 degrees out of phase
(b) Lindenblad antenna
(c) Loaded helical-wound antenna
(d) Axial-mode helical antenna
A-007-005-003
Which of these antennas does not produce circular polarization?
(c) Loaded helical-wound antenna
A-007-005-004
On VHF/UHF frequencies, Doppler shift becomes of consequence on which type of communication?
(a) Contact through a hilltop repeater
(b) Contact via satellite
(c) Simplex line-of-sight contact between hand-held transceivers
(d) Contact with terrestrial mobile stations
A-007-005-004
On VHF/UHF frequencies, Doppler shift becomes of consequence on which type of communication?
(b) Contact via satellite
A-007-005-005
For VHF and UHF signals over a fixed path, what extra loss can be expected when linearly-polarized antennas are crossed-polarized (90 degrees)?
(a) 20 dB or more
(b) 3 dB
(c) 6 dB
(d) 10 dB
A-007-005-005
For VHF and UHF signals over a fixed path, what extra loss can be expected when linearly-polarized antennas are crossed-polarized (90 degrees)?
(a) 20 dB or more
A-007-005-006
Which of the following is NOT a valid parabolic dish illumination arrangement?
(a) Newtonian
(b) Front feed
(c) Offset feed
(d) Cassegrain
A-007-005-006
Which of the following is NOT a valid parabolic dish illumination arrangement?
(a) Newtonian
A-007-005-007
A parabolic antenna is very efficient because:
(a) all the received energy is focused to a point where the pick-up antenna is located
(b) a dipole antenna can be used to pick up the received energy
(c) no impedance matching is required
(d) a horn-type radiator can be used to trap the received energy
A-007-005-007
A parabolic antenna is very efficient because:
(a) all the received energy is focused to a point where the pick-up antenna is located
A-007-005-008
A helical-beam antenna with right-hand polarization will best receive signals with:
(a) right-hand polarization
(b) left-hand polarization
(c) vertical polarization only
(d) horizontal polarization
A-007-005-008
A helical-beam antenna with right-hand polarization will best receive signals with:
(a) right-hand polarization
A-007-005-009
One antenna which will respond simultaneously to vertically- and horizontally-polarized signals is the:
(a) folded dipole antenna
(b) ground-plane antenna
(c) helical-beam antenna
(d) quad antenna
A-007-005-009
One antenna which will respond simultaneously to vertically- and horizontally-polarized signals is the:
(c) helical-beam antenna
A-007-005-010
In amateur work, what is the surface error upper limit you should try not to exceed on a parabolic reflector?
(a) 0.25 lambda
(b) 5 mm (0.2 in) regardless of frequency
(c) 0.1 lambda
(d) 1% of the diameter
A-007-005-010
In amateur work, what is the surface error upper limit you should try not to exceed on a parabolic reflector?
(c) 0.1 lambda
A-007-005-011
You want to convert a surplus parabolic dish for amateur radio use, the gain of this antenna depends on:
(a) the diameter of the antenna in wavelengths
(b) the polarization of the feed device illuminating it
(c) the focal length of the antenna
(d) the material composition of the dish
A-007-005-011
You want to convert a surplus parabolic dish for amateur radio use, the gain of this antenna depends on:
(a) the diameter of the antenna in wavelengths
A-007-006-001
A transmitter has an output of 100 watts. The cable and connectors have a composite loss of 3 dB, and the antenna has a gain of 6 dBd. What is the Effective Radiated Power?
(a) 350 watts
(b) 400 watts
(c) 300 watts
(d) 200 watts
A-007-006-001
A transmitter has an output of 100 watts. The cable and connectors have a composite loss of 3 dB, and the antenna has a gain of 6 dBd. What is the Effective Radiated Power?
(d) 200 watts
A-007-006-002
As standing wave ratio rises, so does the loss in the transmission line. This is caused by:
(a) high antenna currents
(b) high antenna voltage
(c) leakage to ground through the dielectric
(d) dielectric and conductor heat losses
A-007-006-002
As standing wave ratio rises, so does the loss in the transmission line. This is caused by:
(d) dielectric and conductor heat losses
A-007-006-003
What is the Effective Radiated Power of an amateur transmitter, if the transmitter output power is 200 watts, the transmission line loss is 5 watts, and the antenna power gain is 3 dBd?
(a) 197 watts
(b) 228 watts
(c) 178 watts
(d) 390 watts
A-007-006-003
What is the Effective Radiated Power of an amateur transmitter, if the transmitter output power is 200 watts, the transmission line loss is 5 watts, and the antenna power gain is 3 dBd?
(d) 390 watts
A-007-006-004
Effective Radiated Power means the:
(a) power supplied to the antenna before the modulation of the carrier
(b) power supplied to the transmission line plus antenna gain
(c) ratio of signal output power to signal input power
(d) transmitter output power, minus line losses, plus antenna gain relative to a dipole
A-007-006-004
Effective Radiated Power means the:
(d) transmitter output power, minus line losses, plus antenna gain relative to a dipole
A-007-006-005
A transmitter has an output power of 200 watts. The coaxial and connector losses are 3 dB in total, and the antenna gain is 9 dBd. What is the approximate Effective Radiated Power of this system?
(a) 3200 watts
(b) 800 watts
(c) 1600 watts
(d) 400 watts
A-007-006-005
A transmitter has an output power of 200 watts. The coaxial and connector losses are 3 dB in total, and the antenna gain is 9 dBd. What is the approximate Effective Radiated Power of this system?
(b) 800 watts
A-007-006-006
A transmitter has a power output of 100 watts. There is a loss of 1.30 dB in the transmission line, a loss of 0.2 dB through the antenna tuner, and a gain of 4.50 dBd in the antenna. The Effective Radiated Power (ERP) is:
(a) 800 watts
(b) 400 watts
(c) 200 watts
(d) 100 watts
A-007-006-006
A transmitter has a power output of 100 watts. There is a loss of 1.30 dB in the transmission line, a loss of 0.2 dB through the antenna tuner, and a gain of 4.50 dBd in the antenna. The Effective Radiated Power (ERP) is:
(c) 200 watts
A-007-006-007
If the overall gain of an amateur station is increased by 3 dB the ERP (Effective Radiated Power) will:
(a) decrease by 3 watts
(b) remain the same
(c) be cut in half
(d) double
A-007-006-007
If the overall gain of an amateur station is increased by 3 dB the ERP (Effective Radiated Power) will:
(d) double
A-007-006-008
A transmitter has a power output of 125 watts. There is a loss of 0.8 dB in the transmission line, 0.2 dB in the antenna tuner, and a gain of 10 dBd in the antenna. The Effective Radiated Power (ERP) is:
(a) 1250
(b) 1000
(c) 1125
(d) 134
A-007-006-008
A transmitter has a power output of 125 watts. There is a loss of 0.8 dB in the transmission line, 0.2 dB in the antenna tuner, and a gain of 10 dBd in the antenna. The Effective Radiated Power (ERP) is:
(b) 1000
A-007-006-009
If a 3 dBd gain antenna is replaced with a 9 dBd gain antenna, with no other changes, the Effective Radiated Power (ERP) will increase by:
(a) 6
(b) 4
(c) 1.5
(d) 2
A-007-006-009
If a 3 dBd gain antenna is replaced with a 9 dBd gain antenna, with no other changes, the Effective Radiated Power (ERP) will increase by:
(b) 4
A-007-006-010
A transmitter has an output of 2000 watts PEP. The transmission line, connectors and antenna tuner have a composite loss of 1 dB, and the gain from the stacked Yagi antenna is 10 dBd. What is the Effective Radiated Power (ERP) in watts PEP?
(a) 18 000
(b) 16 000
(c) 20 000
(d) 2009
A-007-006-010
A transmitter has an output of 2000 watts PEP. The transmission line, connectors and antenna tuner have a composite loss of 1 dB, and the gain from the stacked Yagi antenna is 10 dBd. What is the Effective Radiated Power (ERP) in watts PEP?
(b) 16 000
A-007-006-011
A transmitter has an output of 1000 watts PEP. The coaxial cable, connectors and antenna tuner have a composite loss of 1 dB, and the antenna gain is 10 dBd. What is the Effective Radiated Power (ERP) in watts PEP?
(a) 8000
(b) 1009
(c) 10 000
(d) 9000
A-007-006-011
A transmitter has an output of 1000 watts PEP. The coaxial cable, connectors and antenna tuner have a composite loss of 1 dB, and the antenna gain is 10 dBd. What is the Effective Radiated Power (ERP) in watts PEP?
(a) 8000
A-007-007-001
For a 3-element Yagi antenna with horizontally mounted elements, how does the main lobe takeoff angle vary with height above flat ground?
(a) It increases with increasing height
(b) It does not vary with height
(c) It decreases with increasing height
(d) It depends on E-region height, not antenna height
A-007-007-001
For a 3-element Yagi antenna with horizontally mounted elements, how does the main lobe takeoff angle vary with height above flat ground?
(c) It decreases with increasing height
A-007-007-002
Most simple horizontally polarized antennas do not exhibit significant directivity unless they are:
(a) an eighth of a wavelength above the ground
(b) a quarter wavelength above the ground
(c) a half wavelength or more above the ground
(d) three-eighths of a wavelength above the ground
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Most simple horizontally polarized antennas do not exhibit significant directivity unless they are:
(c) a half wavelength or more above the ground
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The plane from which ground reflections can be considered to take place, or the effective ground plane for an antenna is:
(a) as much as 6 cm below ground depending upon soil conditions
(b) several centimeters to as much as 2 meters below ground, depending upon soil conditions
(c) as much as a meter above ground
(d) at ground level exactly
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The plane from which ground reflections can be considered to take place, or the effective ground plane for an antenna is:
(b) several centimeters to as much as 2 meters below ground, depending upon soil conditions
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Why is a ground-mounted vertical quarter-wave antenna in reasonably open surroundings better for long distance contacts than a half-wave dipole at a quarter wavelength above ground?
(a) The radiation resistance is lower
(b) It has an omnidirectional characteristic
(c) The vertical radiation angle is lower
(d) It uses vertical polarization
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Why is a ground-mounted vertical quarter-wave antenna in reasonably open surroundings better for long distance contacts than a half-wave dipole at a quarter wavelength above ground?
(c) The vertical radiation angle is lower
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When a half-wave dipole antenna is installed one-half wavelength above ground, the:
(a) radiation pattern changes to produce side lobes at 15 and 50 degrees
(b) side lobe radiation is cancelled
(c) vertical or upward radiation is effectively cancelled
(d) radiation pattern is unaffected
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When a half-wave dipole antenna is installed one-half wavelength above ground, the:
(c) vertical or upward radiation is effectively cancelled
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How does antenna height affect the horizontal (azimuthal) radiation pattern of a horizontal dipole HF antenna?
(a) If the antenna is less than one-half wavelength high, reflected radio waves from the ground significantly distort the pattern
(b) Antenna height has no effect on the pattern
(c) If the antenna is less than one-half wavelength high, radiation off the ends of the wire is eliminated
(d) If the antenna is too high, the pattern becomes unpredictable
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How does antenna height affect the horizontal (azimuthal) radiation pattern of a horizontal dipole HF antenna?
(a) If the antenna is less than one-half wavelength high, reflected radio waves from the ground significantly distort the pattern
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For long distance propagation, the vertical radiation angle of the energy from the antenna should be:
(a) more than 45 degrees but less than 90 degrees
(b) less than 30 degrees
(c) 90 degrees
(d) more than 30 degrees but less than 45 degrees
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For long distance propagation, the vertical radiation angle of the energy from the antenna should be:
(b) less than 30 degrees
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Greater distance can be covered with multiple-hop transmissions by decreasing the:
(a) vertical radiation angle of the antenna
(b) power applied to the antenna
(c) main height of the antenna
(d) length of the antenna
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Greater distance can be covered with multiple-hop transmissions by decreasing the:
(a) vertical radiation angle of the antenna
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The impedance at the centre of a dipole antenna more than 3 wavelengths above ground would be nearest to:
(a) 75 ohms
(b) 25 ohms
(c) 300 ohms
(d) 600 ohms
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The impedance at the centre of a dipole antenna more than 3 wavelengths above ground would be nearest to:
(a) 75 ohms
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Why can a horizontal antenna closer to ground be advantageous for close range communications on lower HF bands?
(a) Lower antenna noise temperature
(b) Low radiation angle for closer distances
(c) The ground tends to act as a reflector
(d) The radiation resistance is higher
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Why can a horizontal antenna closer to ground be advantageous for close range communications on lower HF bands?
(c) The ground tends to act as a reflector
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Which antenna system and operating frequency are most suitable for Near Vertical Incidence (NVIS) communications?
(a) A horizontal antenna less than 1/4 wavelength above ground and a frequency below the current critical frequency
(b) A horizontal antenna at a height of half a wavelength and an operating frequency at the optimum working frequency
(c) A vertical antenna and a frequency below the maximum usable frequency
(d) A vertical antenna and a frequency above the lowest usable frequency
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Which antenna system and operating frequency are most suitable for Near Vertical Incidence (NVIS) communications?
(a) A horizontal antenna less than 1/4 wavelength above ground and a frequency below the current critical frequency
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What is meant by the radiation resistance of an antenna?
(a) The equivalent resistance that would dissipate the same amount of power as that radiated from an antenna
(b) The resistance in the atmosphere that an antenna must overcome to be able to radiate a signal
(c) The specific impedance of an antenna
(d) The combined losses of the antenna elements and transmission line
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What is meant by the radiation resistance of an antenna?
(a) The equivalent resistance that would dissipate the same amount of power as that radiated from an antenna
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Why would one need to know the radiation resistance of an antenna?
(a) To match impedances for maximum power transfer
(b) To measure the near-field radiation density from a transmitting antenna
(c) To calculate the front-to-side ratio of the antenna
(d) To calculate the front-to-back ratio of the antenna
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Why would one need to know the radiation resistance of an antenna?
(a) To match impedances for maximum power transfer
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What factors determine the radiation resistance of an antenna?
(a) Transmission line length and antenna height
(b) Antenna location with respect to nearby objects and the conductors length/diameter ratio
(c) Sunspot activity and time of day
(d) It is a physical constant and is the same for all antennas
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What factors determine the radiation resistance of an antenna?
(b) Antenna location with respect to nearby objects and the conductors length/diameter ratio
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What is the term for the ratio of the radiation resistance of an antenna to the total resistance of the system?
(a) Beamwidth
(b) Effective Radiated Power
(c) Radiation conversion loss
(d) Antenna efficiency
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What is the term for the ratio of the radiation resistance of an antenna to the total resistance of the system?
(d) Antenna efficiency
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What is included in the total resistance of an antenna system?
(a) Radiation resistance plus ohmic resistance
(b) Radiation resistance plus transmission resistance
(c) Transmission line resistance plus radiation resistance
(d) Radiation resistance plus space impedance
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What is included in the total resistance of an antenna system?
(a) Radiation resistance plus ohmic resistance
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How can the approximate beamwidth of a beam antenna be determined?
(a) Draw two imaginary lines through the ends of the elements and measure the angle between the lines
(b) Note the two points where the signal strength is down 3 dB from the maximum signal point and compute the angular difference
(c) Measure the ratio of the signal strengths of the radiated power lobes from the front and side of the antenna
(d) Measure the ratio of the signal strengths of the radiated power lobes from the front and rear of the antenna
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How can the approximate beamwidth of a beam antenna be determined?
(b) Note the two points where the signal strength is down 3 dB from the maximum signal point and compute the angular difference
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How is antenna percent efficiency calculated?
(a) (radiation resistance / transmission resistance) x 100
(b) (radiation resistance / total resistance) x 100
(c) (total resistance / radiation resistance) x 100
(d) (effective radiated power / transmitter output) x 100
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How is antenna percent efficiency calculated?
(b) (radiation resistance / total resistance) x 100
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What is the term used for an equivalent resistance which would dissipate the same amount of energy as that radiated from an antenna?
(a) Radiation resistance
(b) j factor
(c) Antenna resistance
(d) K factor
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What is the term used for an equivalent resistance which would dissipate the same amount of energy as that radiated from an antenna?
(a) Radiation resistance
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Antenna beamwidth is the angular distance between:
(a) the points on the major lobe at the half-power points
(b) the maximum lobe spread points on the major lobe
(c) the 6 dB power points on the major lobe
(d) the 3 dB power points on the first minor lobe
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Antenna beamwidth is the angular distance between:
(a) the points on the major lobe at the half-power points
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If the ohmic resistance of a half-wave dipole is 2 ohms, and the radiation resistance is 72 ohms, what is the antenna efficiency?
(a) 74%
(b) 97.3%
(c) 72%
(d) 100%
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If the ohmic resistance of a half-wave dipole is 2 ohms, and the radiation resistance is 72 ohms, what is the antenna efficiency?
(b) 97.3%
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If the ohmic resistance of a miniloop antenna is 2 milliohms and the radiation resistance is 50 milliohms, what is the antenna efficiency?
(a) 52%
(b) 25%
(c) 50%
(d) 96.15%
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If the ohmic resistance of a miniloop antenna is 2 milliohms and the radiation resistance is 50 milliohms, what is the antenna efficiency?
(d) 96.15%
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Waveguide is typically used:
(a) at frequencies above 2 MHz
(b) at frequencies below 150 MHz
(c) at frequencies above 3000 MHz
(d) at frequencies below 1500 MHz
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Waveguide is typically used:
(c) at frequencies above 3000 MHz
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Which of the following is not correct? Waveguide is an efficient transmission medium because it features:
(a) low hysteresis loss
(b) low radiation loss
(c) low dielectric loss
(d) low copper loss
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Which of the following is not correct? Waveguide is an efficient transmission medium because it features:
(a) low hysteresis loss
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Which of the following is an advantage of waveguide as a transmission line?
(a) Low loss
(b) Frequency sensitive based on dimensions
(c) Expensive
(d) Heavy and difficult to install
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Which of the following is an advantage of waveguide as a transmission line?
(a) Low loss
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For rectangular waveguide to transfer energy, the cross-section should be at least:
(a) one-half wavelength
(b) three-eighths wavelength
(c) one-eighth wavelength
(d) one-quarter wavelength
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For rectangular waveguide to transfer energy, the cross-section should be at least:
(a) one-half wavelength
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Which of the following statements about waveguide IS NOT correct?
(a) In the transverse electric mode, a component of the magnetic field is in the direction of propagation
(b) In the transverse magnetic mode, a component of the electric field is in the direction of propagation
(c) Waveguide has high loss at high frequencies, but low loss below cutoff frequency
(d) Waveguide has low loss at high frequencies, but high loss below cutoff frequency
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Which of the following statements about waveguide IS NOT correct?
(c) Waveguide has high loss at high frequencies, but low loss below cutoff frequency
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Which of the following is a major advantage of waveguide over coaxial cable for use at microwave frequencies?
(a) Frequency response from 1.8 MHz to 24GHz
(b) Very low losses
(c) Easy to install
(d) Inexpensive to install
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Which of the following is a major advantage of waveguide over coaxial cable for use at microwave frequencies?
(b) Very low losses
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What is printed circuit transmission line called?
(a) Dielectric substrate
(b) Dielectric imprinting
(c) Ground plane
(d) Microstripline
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What is printed circuit transmission line called?
(d) Microstripline
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Compared with coaxial cable, microstripline:
(a) has superior shielding
(b) must have much lower characteristic impedance
(c) has poorer shielding
(d) must have much higher characteristic impedance
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Compared with coaxial cable, microstripline:
(c) has poorer shielding
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A section of waveguide:
(a) operates like a low-pass filter
(b) operates like a band-stop filter
(c) operates like a high-pass filter
(d) is lightweight and easy to install
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A section of waveguide:
(c) operates like a high-pass filter
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Stripline is a:
(a) small semiconductor family
(b) printed circuit transmission line
(c) high power microwave antenna
(d) family of fluids for removing coatings from small parts
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Stripline is a:
(b) printed circuit transmission line
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What precautions should you take before beginning repairs on a microwave feed horn or waveguide?
(a) Be sure the weather is dry and sunny
(b) Be sure the transmitter is turned off and the power source is disconnected
(c) Be sure propagation conditions are unfavourable for tropospheric ducting
(d) Be sure to wear tight-fitting clothes and gloves to protect your body and hands from sharp edges
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What precautions should you take before beginning repairs on a microwave feed horn or waveguide?
(b) Be sure the transmitter is turned off and the power source is disconnected
