Feedlines
Characteristic Impedance
Coaxial cable
Open Wire Feedline
Propagation Delay
Balun
SWR - Standing Wave Ratio
Line Loss
Connectors
Basic Qualification Question Bank for Amateur Radio Operator Certificate Examinations 12 June, 2014

Feedlines

(C)

B-006-001-001 What connects your transceiver to your antenna?
A A ground wire
B A dummy load
C A transmission line
D The power cord


Characteristic Impedance

(B)
B-006-001-002 The characteristic impedance of a transmission line is determined by the:
A load placed on the line
B physical dimensions and relative positions of the conductors
C length of the line
D frequency at which the line is operated

(D)
B-006-001-003 The characteristic impedance of a 20 metre piece of transmission line is 52 ohms. If 10 metres were cut off, the impedance would be:
A 26 ohms
B 39 ohms
C 13 ohms
D 52 ohms

(A)
B-006-001-004 The characteristic impedance of a coaxial line:
A can be the same for different diameter line
B changes significantly with the frequency of the energy it carries
C is correct for only one size of line
D is greater for larger diameter line

(B)
B-006-001-005 What commonly available antenna transmission line can be buried directly in the ground for some distance without adverse effects?
A 75 ohm twin-lead
B Coaxial cable
C 300 ohm twin-lead
D 600 ohm open-wire line

(C)
B-006-001-006 The characteristic impedance of a transmission line is:
A the dynamic impedance of the line at the operating frequency
B the ratio of the power supplied to the line to the power delivered to the load
C equal to the pure resistance which, if connected to the end of the line, will absorb all the power arriving along it
D the impedance of a section of the line one wavelength long

(B)
B-006-001-008 The characteristic impedance of a parallel wire transmission line does not depend on the:
A dielectric
B velocity of energy on the line
C radius of the conductors
D centre to centre distance between conductors

(C)
B-006-001-009 If the impedance terminating a transmission line differs significantly from the characteristic impedance of the line, what will be observed at the input of the line?
A A negative impedance
B An impedance nearly equal to the characteristic impedance
C Some value of impedance influenced by line length
D An infinite impedance

(A)
B-006-003-011 TV twin-lead transmission line can be used for a transmission line in an amateur station. The impedance of this line is approximately:
A 300 ohms
B 600 ohms
C 50 ohms
D 70 ohms

Coaxial cable
(A)

B-006-002-001 What is a coaxial cable?
A A center wire inside an insulating material which is covered by a metal sleeve or shield
B Two wires side-by-side in a plastic ribbon
C Two wires side-by-side held apart by insulating rods
D Two wires twisted around each other in a spiral

(B)
B-006-001-011 What factors determine the characteristic impedance of a coaxial antenna transmission line?
A The frequency of the signal and the length of the line
B The ratio of the diameter of the inner conductor to the diameter of the outer shield
C The diameter of the shield and the length of the line
D The diameter of the shield and the frequency of the signal

(C)

B-006-002-006 What is an unbalanced line?
A Transmission line with both conductors connected to ground
B Transmission line with both conductors connected to each other
C Transmission line with one conductor connected to ground
D Transmission line with neither conductor connected to ground

(D)

B-006-002-008 A flexible coaxial line contains:
A four or more conductors running parallel
B only one conductor
C two parallel conductors separated by spacers
D braided shield conductor and insulation around a central conductor

(B)

B-006-003-001 Why does coaxial cable make a good antenna transmission line?
A You can make it at home, and its impedance matches most amateur antennas
B It is weatherproof, and its impedance matches most amateur antennas
C It is weatherproof, and its impedance is higher than that of most amateur antennas
D It can be used near metal objects, and its impedance is higher than that of most amateur antennas

(D)
B-006-003-002 What is the best antenna transmission line to use, if it must be put near grounded metal objects?
A Ladder-line
B Twisted pair
C Twin lead
D Coaxial cable

(D)
B-006-003-009 What commonly available antenna transmission line can be buried directly in the ground for some distance without adverse effects?
A 75 ohm twin-lead
B 600 ohm open wire line
C 300 ohm twin-lead
D Coaxial cable

(A)
B-006-003-010 When antenna transmission lines must be placed near grounded metal objects, which of the following transmission lines should be used?
A Coaxial cable
B 300 ohm twin-lead
C 600 ohm open wire line
D 75 ohm twin-lead

Open Wire Feedline
(B)

B-006-002-002 What is parallel-conductor transmission line?
A A metal pipe which is as wide or slightly wider than a wavelength of the signal it carries
B Two wires side-by-side held apart by insulating material
C Two wires twisted around each other in a spiral
D A center wire inside an insulating material which is covered by a metal sleeve or shield

(D)
B-006-002-003 What kind of antenna transmission line is made of two conductors held apart by insulated rods?
A Coaxial cable
B Twin lead in a plastic ribbon
C Twisted pair
D Open wire line

(D)

B-006-001-010 What factors determine the characteristic impedance of a parallel-conductor antenna transmission line?
A The distance between the centres of the conductors and the length of the line
B The radius of the conductors and the frequency of the signal
C The frequency of the signal and the length of the line
D The distance between the centres of the conductors and the radius of the conductors

(D)
B-006-002-009 A balanced transmission line:
A has one conductor inside the other
B carries RF current on one wire only
C is made of one conductor only
D is made of two parallel wires

(B)
B-006-002-011 What kind of antenna transmission line can be constructed using two conductors which are maintained a uniform distance apart using insulated spreaders?
A 300 ohm twin-lead
B 600 ohm open wire line
C Coaxial cable
D 75 ohm twin-lead

(A)

B-006-003-003 What are some reasons not to use parallel-conductor transmission line?
A It does not work well when tied down to metal objects, and you should use a balun and may have to use an impedance-matching device with your transceiver
B You must use an impedance-matching device with your transceiver, and it does not work very well with a high SWR
C It does not work well when tied down to metal objects, and it cannot operate under high power
D It is difficult to make at home, and it does not work very well with a high SWR

(B)
B-006-004-002 What are some reasons to use parallel-conductor transmission line?
A It has a low impedance, and has less loss than coaxial cable
B It will operate with a high SWR, and has less loss than coaxial cable
C It has low impedance, and will operate with a high SWR
D It will operate with a high SWR, and it works well when tied down to metal objects


Propagation Delay
(D)

B-006-001-007 A transmission line differs from an ordinary circuit or network in communications or signalling devices in one very important way. That important aspect is:
A capacitive reactance
B inductive reactance
C resistance
D propagation delay


Balun
(B)

B-006-002-004 What does the term "balun" mean?
A Balanced antenna network
B Balanced to unbalanced
C Balanced unloader
D Balanced unmodulator

(B)
B-006-002-005 Where would you install a balun to feed a dipole antenna with 50-ohm coaxial cable?
A Between the coaxial cable and the ground
B Between the coaxial cable and the antenna
C Between the transmitter and the coaxial cable
D Between the antenna and the ground

(C)

B-006-002-007 What device can be installed to feed a balanced antenna with an unbalanced transmission line?
A A wave trap
B A loading coil
C A balun
D A triaxial transformer

(B)

B-006-002-010 A 75 ohm transmission line could be matched to the 300 ohm feed point of an antenna:
A by inserting a diode in one leg of the antenna
B by using a 4 to 1 impedance transformer
C with an extra 250 ohm resistor
D by using a 4 to 1 trigatron

SWR - Standing Wave Ratio
(A)

B-006-005-001 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

(A)
B-006-005-002 What does an SWR reading of less than 1.5:1 mean?
A A fairly good impedance match
B An impedance match which is too low
C A serious impedance mismatch; something may be wrong with the antenna system
D An antenna gain of 1.5

(B)
B-006-005-003 What kind of SWR reading may mean poor electrical contact between parts of an antenna system?
A A very low reading
B A jumpy reading
C A negative reading
D No reading at all

(C)
B-006-005-004 What does a very high SWR reading mean?
A There is a large amount of solar radiation, which means very poor radio conditions
B The signals coming from the antenna are unusually strong, which means very good radio condition
C The antenna is the wrong length for the operating frequency, or the transmission line may be open or short circuited
D The transmitter is putting out more power than normal, showing that it is about to go bad

(B) What does standing-wave ratio mean?
A The ratio of maximum to minimum impedances on a transmission line
B The ratio of maximum to minimum voltages on a transmission line
C The ratio of maximum to minimum inductances on a transmission line
D The ratio of maximum to minimum resistances on a transmission line

(A)
B-006-005-006 If your antenna transmission line gets hot when you are transmitting, what might this mean?
A The SWR may be too high, or the transmission line loss may be high
B You should transmit using less power
C The conductors in the transmission line are not insulated very well
D The transmission line is too long

(D)
B-006-005-007 If the characteristic impedance of the transmission 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 in the transmission line

(B)
B-006-005-008 The result of the presence of standing waves on a transmission line is:
A lack of radiation from the transmission line
B reduced transfer of RF energy to the antenna
C perfect impedance match between transmitter and transmission line
D maximum transfer of energy to the antenna from the transmitter

(C)
B-006-005-009 An SWR meter measures the degree of match between transmission line and antenna by:
A measuring the conductor temperature
B inserting a diode in the transmission line
C comparing forward and reflected voltage
D measuring radiated RF energy

(C)
B-006-005-010 A resonant antenna having a feed point impedance of 200 ohms is connected to a transmission line which has an impedance of 50 ohms. What will the standing wave ratio of this system be?
A 3:1
B 5:1
C 4:1
D 6:1

(D)
B-006-005-011 The type of transmission line best suited to operating at a high standing wave ratio is:
A 75 ohm twin-lead
B coaxial line
C 300 ohm twin-lead
D 600 ohm open wire line

Line Loss
(C)

B-006-003-007 If you install a 6 metre Yagi on a tower 60 metres(200 ft) from your transmitter, which of the following transmission lines provides the least loss?
A RG-59
B RG-58
C RG-213
D RG-174

(C)
B-006-004-001 Why should you use only good quality coaxial cable and connectors for a UHF antenna system?
A To keep the power going to your antenna system from getting too high
B To keep the standing wave ratio of your antenna system high
C To keep RF loss low
D To keep television interference high

(B)
B-006-004-003 If your transmitter and antenna are 15 metres(50 ft) apart, but are connected by 60 metres(200 ft) of RG-58 coaxial cable, what should be done to reduce transmission line loss?
A Shorten the excess cable so the transmission line is an even number of wavelengths long
B Shorten the excess cable
C Shorten the excess cable so the transmission line is an odd number of wavelengths long
D Roll the excess cable into a coil which is as small as possible

(C)
B-006-004-004 As the length of a transmission line is changed, what happens to signal loss?
A Signal loss is the least when the length is the same as the signal's wavelength
B Signal loss is the same for any length of transmission line
C Signal loss increases as length increases
D Signal loss decreases as length increases

(B)
B-006-004-005 As the frequency of a signal is changed, what happens to signal loss in a transmission line?
A Signal loss is the same for any frequency
B Signal loss increases with increasing frequency
C Signal loss increases with decreasing frequency
D Signal loss is the least when the signal's wavelength is the same as the transmission line's length

(A)
B-006-004-006 Losses occurring on a transmission line between transmitter and antenna results in:
A less RF power being radiated
B an SWR reading of 1:1
C reflections occurring in the line
D the wire radiating RF energy

(C)
B-006-004-007 The lowest loss transmission line on HF is:
A coaxial cable
B 300 ohm twin-lead
C open wire line
D 75 ohm twin-lead

(A)
B-006-004-008 In what values are RF transmission line losses expressed?
A dB per unit length
B Ohms per MHz
C dB per MHz
D Ohms per metre

(A)
B-006-004-009 If the length of coaxial transmission line is increased from 20 metres(66 ft) to 40 metres(132 ft), how would this affect the line loss?
A It would be increased by 100%
B It would be reduced by 10%
C It would be increased by 10%
D It would be reduced to 50%

(C)
B-006-004-010 If the frequency is increased, how would this affect the loss on a transmission line?
A It depends on the line length
B It would decrease
C It would increase
D It is independent of frequency

Connectors

(D)

B-006-003-004 What common connector type usually joins RG-213 coaxial cable to an HF transceiver?
A An F-type cable connector
B A banana plug connector
C A binding post connector
D A PL-259 connector

(A)
B-006-003-005 What common connector usually joins a hand-held transceiver to its antenna?
A An SMA connector
B A PL-259 connector
C An F-type cable connector
D A binding post connector

(D)
B-006-003-006 Which of these common connectors has the lowest loss at UHF?
A An F-type cable connector
B A BNC connector
C A PL-259 connector
D A type-N connector

(A)

B-006-003-008 Why should you regularly clean and tighten all antenna connectors?
A To help keep their contact resistance at a minimum
B To keep them looking nice
C To keep them from getting stuck in place
D To increase their capacitance
The Georgian Bay Amateur Radio Club
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Ontario Canada N4K5P1
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November 20, 2017