- What connects your transceiver to the antenna?
A. The power cord.
B. A ground wire.
C. A feed line.
D. A dummy load.
- What is a parallel-conductor feed line?
A. Two wires twisted around each other in a spiral.
B. A center wire inside an insulating material that is covered by a metal
shield or sleeve.
C. A metal pipe that is as wide or slightly wider than a wavelength of the
signal it carries.
D. Two wires side-by-side held apart by insulating rods.
- What kind of antenna feed line is made of two conductors held apart by insulated
rods?
A. Open-conductor ladder line.
B. Coaxial cable.
C. Twin lead in a plastic ribbon.
D. Twisted pair.
- A balanced transmission line:
A. is made of two parallel wires.
B. has one conductor inside the other.
C. carries RF on one wire only.
D. is made of one conductor only.
- What kind of antenna feed line can be constructed using two conductors that are
maintained at a uniform distance apart using insulated spreaders?
A. Coaxial cables.
B. 75 ohm twin-lead.
C. 600 ohm open-wire.
D. 300 ohm twin-lead.
- What are some reasons not to use parallel-conductor feed lines?
A. You must use an impedance-matching device with your transceiver, and it
does not work very well with a high SWR.
B. It does not work well when tied down to metal objects, and it cannot
operate under high power.
C. It does not work well when tied down to metal objects, and you must use
an impedance matching device with your transceiver.
D. It is difficult to make at home, and it does not work very well with a high
SWR.
- What are some reasons to use parallel-conductor feed line?
A. It will operate with a high SWR, and has less loss than coaxial cable.
B. It has a low impedance, and will operate with a high SWR.
C. It will operate with a high SWR, and it works well when tied down to
metal objects.
D. It has low impedance, and it has less loss than coaxial cable.
- The lowest loss feed line on HF is:
A. open wire.
B. 75 ohm twin-lead.
C. Coaxial cable.
D. 300 ohm twin-lead.
- The characteristic impedance of a transmission line is determined by:
A. length of line.
B. physical dimensions and relative positions of the conductors.
C. frequency at which the line is operated.
D. load placed on the line.
- The characteristic impedance of a transmission line is:
A. the impedance of a section of the line one wavelength long.
B. the dynamic impedance of the line at the operating frequency.
C. the ratio of the power supplied to the line to the power delivered to the
termination.
D. equal to a pure resistance which, if connected to the end of the line, will
absorb the power arriving along it.
- A transmission lines differs from a normal circuit or network in communications
or signaling devices in one very important way. The important aspect is:
A. capacitive reactance.
B. inductive reactance.
C. propagation delay.
D. resistance.
- The characteristic impedance of a parallel wire transmission line does not depend
on:
A. velocity of energy on the line.
B. radius of the conductor.
C. center to center distance between conductors.
D. dielectric.
- Any length of transmission line may be made to appear as an infinitely long line
by:
A. terminating the line in its characteristic impedance.
B. leaving the line open at the end.
C. shorting the line at the end.
D. increasing the standing wave ratio above unity.
- What 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
conductors.
B. The distance between the centers of the conductors and the length of the
line.
C. The radius of the conductors and the frequency of the signals.
D. The frequency of the signal and the length of the line.
- TV twin-lead can be used as a feed line in an amateur station. The
impedance of this line is:
A. 600 ohms.
B. 50 ohms.
C. 300 ohms.
D. 70 ohms.
- What is an unbalanced line?
A. Feed line with neither conductor connected to ground.
B. Feed line with both conductors connected to ground.
C. Feed line with both conductors connected to each other.
D. Feed line with one conductor connected to ground.
- What is a coaxial cable?
A. Two wires side-by-side in a plastic ribbon.
B. Two wires side-by-side held apart by insulating rods.
C. Two wires twisted around each other in a spiral.
D. A center wire inside an insulating material which is covered by a metal
shield or sleeve.
- A flexible coaxial cable contains:
A. four or more conductors running parallel.
B. only one conductor.
C. braid and insulation around a center conductor.
D. two parallel conductors separated by spacers.
- What is the best antenna feed line to use, if it must be put near grounded metal
objects?
A. Ladder-line.
B. Twisted pair.
C. Coaxial cable.
D. Twin lead.
- Why does coaxial cable make a good antenna feed line?
A. It is waterproof, and its impedance is higher that that of most amateur
antennas.
B. It is waterproof, and its impedance matches most amateur antennas.
C. It can be used near metal objects, and its impedance is higher than that of
most amateur antennas.
D. You can make it at home, and its impedance matches most amateur
antennas.
- When antenna feed lines must be placed near grounded metal objects, which of
the following feed lines should be used?
A. 300 ohm twin-lead.
B. 600 ohm open-wire.
C. 75 ohm twin-lead.
D. Coaxial cable.
- The impedance of a coaxial cable:
A. can be the same for different diameter lines.
B. changes with the frequency of the energy it carries.
C. is correct for only one size of line.
D. is greater for larger diameter lines.
- What commonly available antenna feed line can be buried directly in the ground
for some distance without adverse effects?
A. 300 ohm twin-lead.
B. 600 ohm open-wire.
C. 75 ohm twin-lead.
D. Coaxial cable.
- What factors determines the characteristic impedance of a coaxial antenna feed
line?
A. The ratio of the diameter of the inner wire to the diameter of the
braid.
B. The diameter of the braid and the length of the line.
C. The diameter of the braid and the frequency of the signal.
D. The frequency of the signal and the length of the line.
- The characteristic impedance of a 20 meter piece of transmission line is 52 ohms.
If a 10 meter piece were cut off, the impedance would be:
A. 52 ohms.
B. 26 ohms.
C. 39 ohms.
D. 13 ohms.
- If your antenna and transmitter are 15 meters apart, but are connected by 65
meters of RG-58 coaxial cable, what should be done to reduce feed line loss?
A. Shorten the excess cable so the feed line is an odd number of wavelengths
long.
B. Shorten the excess cable.
C. Roll the excess cable into a coil which is as small as possible.
D. Shorten the excess cable so the feed line is an even number of
wavelengths long.
- As the length of the feed line is changed, what happens to signal loss?
A. Signal loss decreases as length increases.
B. Signal loss increases as length increases.
C. Signal loss is the least when the length is the same as the signal’s
wavelength.
D. Signal loss is the same for any length of feed line.
- As the frequency of the signal is changed, what happens to signal loss in the feed
line?
A. Signal loss increases with decreasing frequency.
B. Signal loss increases with increasing frequency.
C. Signal loss is the least when the signal’s wavelength is the same as the
feed lines length.
D. Signal loss is the same for any frequency.
- If the length of coaxial feed line is increased from 20 meters (65.6 ft) to 40 meters
(131.2 ft), how would this affect the line loss?
A. It would increase by 100%.
B. It would be reduced by 10%.
C. It would be increased by 10%.
D. It would be reduced by 50%.
- In what values are RF feed line losses expressed?
A. ohms per MHz.
B. dB per MHz.
C. ohms per meter.
D. dB per unit length.
- If the frequency is increased, how would this affect the loss on a transmission
line?
A. It is independent of frequency.
B. It would increase.
C. It depends on the line length.
D. It would decrease.
- What does the word "balun" mean?
A. Balanced unloader.
B. Balanced to unbalanced.
C. Balanced unmodulator.
D. Balanced antenna network.
- Where would you install a balun to feed a dipole antenna with a 50-ohm coaxial
cable?
A. Between the coaxial cable and the antenna.
B. Between the transmitter and the coaxial cable.
C. Between the antenna and the ground.
D. Between the coaxial cable and the ground.
- What device can be install to feed a balanced antenna with an unbalanced feed
line?
A. A triaxial transformer.
B. A balun.
C. A wavetrap.
D. A loading coil.
- A 75 ohm transmission line can be matched to the 300 ohm feed point of an
antenna:
A. with an extra 250 ohm resistor.
B. By using a 4 to 1 balun.
C. By using a 4 to 1 trigatron.
D. By inserting a diode in one leg of the antenna.
- What does standing-wave ratio mean?
A. The ratio of the maximum to minimum voltages on a feed line.
B. The ratio of the maximum to minimum inductances on a feed line.
C. The ratio of maximum to minimum resistances on the feed line.
D. The ratio of maximum to minimum impedances on a feed line.
- What does a very high SWR reading mean?
A. The transmitter is putting out more power than normal, showing that it is
about to go bad.
B. The antenna is the wrong wavelength, or there may be an open or shorted
connection somewhere in the feed line.
C. There is a large amount of solar radiation, which means very poor radio
communications.
D. The signals coming from the antenna are unusually strong, which means
very good radio conditions.
- If your antenna feed line gets hot when you are transmitting, what might this
mean?
A. You should transmit using less power.
B. The conductors in the feed line are not insulated very well.
C. The feed line is too long.
D. The SWR may be too high, or the feed line loss may be high.
- If the characteristic impedance of the feed line does not match the antenna input
impedance then:
A. heat is produced at the junction.
B. the SWR reading falls to 1:1.
C. the antenna will not radiate any signal.
D. standing waves are produced on the feed line.
- Losses occurring on a transmission line between transmitter and antenna results
in:
A. an SWR of 1:1.
B. less RF power being radiated.
C. reflections occurring on the line.
D. the wire radiating RF energy.
- The results of the presence of standing waves on a transmission line is:
A. perfect impedance match between transmitter and feed line.
B. Maximum transfer of energy to the antenna from the transmitter.
C. Lack of radiation from the transmission line.
D. Reduced transfer of RF energy to the antenna.
- An SWR meter measures the degree of match between transmission line and
antenna by:
A. comparing forward and reflected voltage.
B. measuring the radiated RF energy.
C. measuring the conductor temperature.
D. inserting a diode in the feed line.
- What does an SWR reading of 1:1 mean?
A. The best impedance match has been attained.
B. An antenna for another frequency band is probably connected.
C. No power is going to the antenna.
D. The SWR meter is broken.
- What does an SWR reading of less than 1.5:1 mean?
A. A fairly good impedance match.
B. An impedance match that is too low.
C. An impedance mismatch; something may be wrong with the antenna
system.
D. An antenna gain of 1.5.
- What kind of SWR reading may mean poor electrical contact between parts of the
antenna system?
A. A negative reading.
B. No reading at all.
C. A jumpy reading.
D. A very low reading.
- A resonant antenna having a feed point impedance of 200 ohms is connected to a
feed line and transmitter that has an impedance of 50 ohms. What will the
standing wave ratio of this system be?
A. 6:1
B. 3:1
C. 4:1
D. 5:1
- The type of feed line best suited to operating at a high standing wave ratio is:
A. 75 ohm twin-lead.
B. 600 ohm open-wire.
C. coaxial cable.
D. 300 ohm twin-lead.
- If the center impedance of a folded dipole antenna is approximately
300 ohms, and you are using RG-8U (50 ohms) coaxial lines, what is the
ratio required to have the line and antenna matched?
A. 2:1
B. 4:1
C. 10:1
D. 6:1
- The reason that an RF transmission line should be matched at the
transmitter end is to:
A. ensure that the radiated signal has the intended polarization.
B. transfer the maximum amount of power to the antenna.
C. prevent frequency drift.
D. overcome fading of the transmitted signal.
- If antenna is correctly matched to the transmitter, the length of transmission line:
A. must be a full wavelength long.
B. must be an odd number of quarter-wave.
C. must be an even number of half-waves.
D. will have no effect on matching.
- What happens when the impedance of an electrical load is equal to the internal
impedance of the power source?
A. The electrical load is shorted.
B. The source delivers maximum power to the load.
C. No current can flow through the circuit.
D. The source delivers minimum power to the load.
- Why is impedance matching important?
A. So the load will draw minimum power from the source.
B. To ensure that there is less resistance than reactance in the circuit.
C. To ensure the resistance and reactance is the same.
D. So the source can deliver maximum power to the load.
- To obtain efficient power transmission from the transmitter to antenna requires:
A. high load impedance.
B. low ohmic resistance.
C. matching of impedance.
D. inductive impedance.
- When will a power source deliver maximum output to the load?
A. When air wound transformers are used instead of iron-core transformers.
B. When the power-supply fuse rating equals the primary winding current.
C. When the impedance of the load equals the impedance of the source.
D. When the load resistance is infinite.
- What device might allow use of an antenna on a band it was not designed for?
A. An antenna tuner.
B. An SWR meter.
C. A low pass filter.
D. A high pass filter.
- What does an antenna matching unit do?
A. It matches a transmitter to a mismatched antenna system.
B. It helps a receiver automatically tune in stations that are too far away.
C. It switches an antenna system to a transmitter when sending, and to
receive when receiving.
D. It switches a transceiver between different kinds of antennas connected to
one feed line.
- What would you use to connect a coaxial cable of 50 ohms impedance to an
antenna of 35 ohms impedance?
A. An SWR meter.
B. An impedance-matching device.
C. A low pass filter.
D. A terminating resistor.
- If you install a 6 meter Yagi antenna on a tower 50 meters from your transmitter,
which of the following feed lines is best?
A. RG-174.
B. RG-59.
C. RG-213.
D. RG-58.
- Why should you use good quality coaxial cable and connectors for a UHF antenna
system?
A. To keep television interference high.
B. To keep power going to your antenna from getting too high.
C. To keep the standing wave ratio of your antenna system high.
D. To keep RF loss low.
- What common connector usually joins RG-213 coaxial cable to a HF transmitter?
A. A PL-239 connector.
B. An F-type connector.
C. A banana plug connector.
D. A binding post connector.
- What common connector usually joins a hand-held transceiver to its antenna?
A. A BNC connector.
B. A PL-239 connector.
C. An F-type connector.
D. A binding post connector.
- Which of these common connectors has the lowest loss at UHF?
A. An F-type cable connector.
B. A BNC connector.
C. A PL-239 connector.
D. A type-N connector.
- Why should you regularly clean, tighten and re-solder all antenna connections?
A. To help keep their resistance at a minimum.
B. To keep them looking nice.
C. To keep them from getting stuck in place.
D. To increase their capacity.