Amateur Extra Licensing Class

1
Amateur Extra Licensing Class
Feedlines Safety

• Lake Area Radio Klub
• Spring 2012

2
Amateur Radio Extra ClassElement 4 Course
Presentation

• ELEMENT 4 Groupings
• Rules Regs
• Skywaves Contesting
• Outer Space Comms
• Visuals Video Modes
• Digital Excitement with Computers Radios
• Modulate Your Transmitters
• Amps Power Supplies
• Receivers with Great Filters

3
Amateur Radio Extra ClassElement 4 Course
Presentation

• ELEMENT 4 Groupings
• Oscillate Synthesize This!
• Circuits Resonance for All!
• Components in Your New Rig
• Logically Speaking of Counters
• Optos OpAmps Plus Solar
• Test Gear, Testing, Testing 1,2,3
• Antennas
• Feedlines Safety

4
Amateur Radio Extra ClassFeedlines Safety

• E9E01 The delta matching system matches 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 each side of element center.

5
Amateur Radio Extra ClassFeedlines Safety

• E9E02 The gamma match is a system that matches
  an unbalanced feed line to an antenna by feeding
  the driven element both at the center of the
  element and at a fraction of a wavelength to one
  side of center.
• E9E03 The stub match uses a section of
  transmission line shorted at the end and
  connected to the feed line near the antenna.

6
Amateur Radio Extra ClassFeedlines Safety
Impedance Matching Stubs
(1) Since a short at end makes the diagram look
like a long wire, this indicates the impedance is
an inductive reactance.
(2) Since an open at end makes the diagram look
like two parallel plates, this indicates the
impedance is a capacitive reactance.
7
Amateur Radio Extra ClassFeedlines Safety
Impedance Matching Stubs
(1) Since a short at the extreme end implies an
open a quarter-wave away, this makes the diagram
look like two parallel plates, which indicates
the impedance is a capacitive reactance.
(2) Since an open at the extreme end implies a
short a quarter-wave away, this makes the diagram
look like a long wire, which indicates the
impedance is a inductive reactance.
8
Amateur Radio Extra ClassFeedlines Safety

• E9E04 The purpose of the series capacitor in a
  gamma-type antenna matching network is to
  compensate for the inductive reactance of the
  matching network.
• E9E05 The driven element reactance must be
  capacitive in a 3-element Yagi to be tuned using
  a hairpin matching system.

9
Amateur Radio Extra ClassFeedlines Safety

• E9E06 The equivalent lumped-constant network for
  a hairpin matching system on a 3-element Yagi is
  an L network.
• E9E07 Reflection coefficient best describes the
  interactions at the load end of a mismatched
  transmission line.

The terms - VSWR, Return Loss, Reflected Power
are all ways to describe match or mismatch
between a transmitter and antenna system
With a VSWR of 1.4 to 1 only 2.8 of the
transmitter power is reflected back.
Impedance Mismatch Causes Reflected Wave
10
Amateur Radio Extra ClassFeedlines Safety

• E9E08 An SWR greater than 11 measurement
  describes a mismatched transmission line.

SWR is the ratio of the maximum voltage
(resulting from the interaction of Incident and
reflected voltages along a transmission line) to
the minimum voltage.
SWR Bridges
11
Amateur Radio Extra ClassFeedlines Safety

• E9E09 Using a Gamma match is an effective method
  of connecting a 50-ohm coaxial cable feed-line to
  a grounded tower so it can be used as a vertical
  antenna.
• E9E10 Inserting a 1/4-wavelength piece of 75-ohm
  coaxial cable transmission line in series between
  the antenna terminals and the 50-ohm feed cable
  is an effective way to match an antenna with
  100-ohm terminal impedance to a 50-ohm coaxial
  cable feed-line.
• E9E11 An effective way of matching a feed-line
  to a VHF or UHF antenna when the impedances of
  both the antenna and feed-line are unknown is to
  use the "universal stub" matching technique.

12
Amateur Radio Extra ClassFeedlines Safety

• E9E12 The primary purpose of a "phasing line"
  when used with an antenna having multiple driven
  elements is to ensure that each driven element
  operates in concert with the others to create the
  desired antenna pattern.

Coaxial Cable
13
Amateur Radio Extra ClassFeedlines Safety
.Phasing line cont.
Dual Transmission Line
14
Amateur Radio Extra ClassFeedlines Safety

• E9E13 The purpose of a "Wilkinson divider is to
  divide power equally among multiple loads while
  preventing changes in one load from disturbing
  power flow to the others.
• E9F08 Velocity factor is the term for the ratio
  of the actual speed at which a signal travels
  through a transmission line to the speed of light
  in a vacuum.

15
Amateur Radio Extra ClassFeedlines Safety

• E9F01 The velocity factor of a transmission line
  is the velocity of the wave in the transmission
  line divided by the velocity of light in a
  vacuum.
• E9F02 The transmission line dielectric materials
  used determine the velocity factor in a
  transmission line.
• E9F04 The typical velocity factor for a coaxial
  cable with solid polyethylene dielectric is 0.66.
  
• E9F03 Because electrical signals move more
  slowly in a coaxial cable than in air, the
  physical length of a coaxial cable transmission
  line is shorter than its electrical length.

Velocity Factor Velocity of wave in
Transmission line / Velocity of light
16
Amateur Radio Extra ClassFeedlines Safety

• E9F05The physical length of a coaxial
  transmission line that is electrically
  one-quarter wavelength long at 14.1 MHz is
  (Assuming a velocity factor of 0.66) 3.5 Meters.
• E9F06 The physical length of a parallel
  conductor feed line that is electrically one-half
  wavelength long at 14.10 MHz (Assuming a velocity
  factor of 0.95) is 10 meters.

¼ Wavelength (in Transmission line)
(300/F(MHz)) / 4 x Velocity Factor
¼ Wavelength (in Transmission line) (300/14.1 x
.66) / 4
3.51 meters
14.04/4
½ Wavelength (in Transmission line)
(300/F(MHz))/2 x Velocity Factor
½ Wavelength (in Transmission line) (300/14.1 x
.95)/2
20.21/2
10.10 meters
17
Amateur Radio Extra ClassFeedlines Safety

• E9F07 450-ohm ladder line, at 50 MHz, will have
  a lower loss when compared to 0.195-inch-diameter
  coaxial cable (such as RG-58).
• E9F09 The physical length of a typical coaxial
  transmission line that is electrically
  one-quarter wavelength long at 7.2 MHz (Assume a
  velocity factor of 0.66) would be 6.9 meters.

¼ Wavelength in Transmission line)
(300/F(MHz))/4 x Velocity Factor
¼ Wavelength in Transmission line) (300/7.2
x..66)/4
27.50/4
6.87 meters
18
Amateur Radio Extra ClassFeedlines Safety

• E9F10 A 1/8 wavelength transmission line
  presents an inductive reactance to a generator
  when the line is shorted at the far end.
• E9F11 A 1/8 wavelength transmission line
  presents a capacitive reactance to a generator
  when the line is open at the far end.

Short Circuit at Antenna ZA 0
Impedance of coaxial stubs Impedance of coaxial stubs Impedance of coaxial stubs
Wavelength Open Stub Shorted Stub
1/8 Capacitive Inductive
1/4 Low Imp. High Imp.
1/2 High Imp. Low Imp.
Open Circuit at Antenna ZA 8
19
Amateur Radio Extra ClassFeedlines Safety

• E9F12 A ¼ wavelength transmission line presents
  a very low impedance to a generator when the line
  is open at the far end.
• E9F13 A ¼ wavelength transmission line presents
  a very high impedance to a generator when the
  line is shorted at the far end.

Open Circuit at Antenna ZA 8
Impedance of coaxial stubs Impedance of coaxial stubs Impedance of coaxial stubs
Wavelength Open Stub Shorted Stub
1/8 Capacitive Inductive
1/4 Low Imp. High Imp.
1/2 High Imp. Low Imp.
Short Circuit at Antenna ZA 0
20
Amateur Radio Extra ClassFeedlines Safety

• E9F14 A ½ wavelength transmission line presents
  a very low impedance to a generator when the line
  is shorted at the far end.
• E9F15 A ½ wavelength transmission line presents
  very high impedance to a generator when the line
  is open at the far end.

Short Circuit at Antenna ZA 0
Impedance of coaxial stubs Impedance of coaxial stubs Impedance of coaxial stubs
Wavelength Open Stub Shorted Stub
1/8 Capacitive Inductive
1/4 Low Imp. High Imp.
1/2 High Imp. Low Imp.
Open Circuit at Antenna ZA 8
21
Amateur Radio Extra ClassFeedlines Safety

• E9F16 The primary differences between
  foam-dielectric coaxial cable as opposed to
  solid-dielectric cable, assuming all other
  parameters are the same are reduced safe
  operating voltage limits, reduced losses per unit
  of length and higher velocity factor.

Coax Cable Type, Size and Loss per 100 Feet Coax Cable Type, Size and Loss per 100 Feet Coax Cable Type, Size and Loss per 100 Feet Coax Cable Type, Size and Loss per 100 Feet
Coax Type Size Loss/100MHz Loss/400MHz
RG-6 Large 2.3 dB 4.7 dB
RG-59 Medium 2.9 dB 5.9 dB
RG-58U Small 4.3 dB 9.4 dB
RG-8X Medium 3.7 dB 8.0 dB
RG-8U Large 1.9 dB 4.1 dB
RG-213 Large 1.9 dB 4.5 dB
Hardliner Large, Rigid 0.5 dB 1.5 dB
22
Amateur Radio Extra ClassFeedlines Safety

• E4A07 The advantage of using an antenna analyzer
  vs. a SWR bridge to measure antenna SWR is that
  antenna analyzers typically do not need an
  external RF source.
• E4B12 When using a portable SWR analyzer to
  measure antenna resonance and feed-point
  impedance, connect the antenna feed line directly
  to the analyzer's test connector.

23
Amateur Radio Extra ClassFeedlines Safety

• E9G01 Impedance along transmission lines can be
  calculated using a Smith chart.

Finding Antenna Impedance, ZA, when Fed with
Known Length of Transmission Line ( in
Wavelengths) of Given Impedance, ZO.
Smith Chart
24
Amateur Radio Extra ClassFeedlines Safety

• E4A08 An antenna analyzer would be best for
  measuring the SWR of a beam antenna.

AntennaSmithautomatic antenna impedance analyzer
25
Amateur Radio Extra ClassFeedlines Safety

• E9G02 The coordinate system is used in a Smith
  chart is resistance circles and reactance arcs.

Circles
Arcs
26
Amateur Radio Extra ClassFeedlines Safety

• E9G03 Impedance and SWR values in transmission
  lines are often determined using a Smith chart.
• E9G04 Resistance and reactance are the two
  families of circles and arcs that make up a Smith
  chart.
• E9G05 The type of chart shown in Figure E9-3 is
  a Smith chart.

Figure E9-3
27
Amateur Radio Extra ClassFeedlines Safety

• E9G06 On the Smith chart shown in Figure E9-3,
  the name of the large outer circle on which the
  reactance arcs terminate is the reactance axis.
• E9G07 On the Smith chart shown in Figure E9-3,
  the only straight line shown is the resistance
  axis.

Smith Charts save hours of work.
Figure E9-3
28
Amateur Radio Extra ClassFeedlines Safety

• E9G08 The process of normalization with regard
  to a Smith chart is reassigning impedance values
  with regard to the prime center.
• E9G09 Standing-wave ratio circles are a third
  family of circles that are often added to a Smith
  chart during the process of solving problems.
• E9F10 The arcs on a Smith chart represent points
  with constant reactance.
• E9G11 The wavelength scales on a Smith chart are
  calibrated in fractions of transmission line
  electrical wavelength.

29
Amateur Radio Extra ClassFeedlines Safety

• E9C04 A basic rhombic antenna is a
  bidirectional. It is four-sided. Each side is
  one or more wavelengths long and is open at the
  end opposite the transmission line connection.
• E9C05 The main advantages of a terminated
  rhombic antenna are wide frequency range, high
  gain and high front-to-back ratio (gain).

Open ended
Terminated
30
Amateur Radio Extra ClassFeedlines Safety

• E9C06 The disadvantages of a terminated rhombic
  antenna for the HF bands are that the antenna
  requires a large physical area and 4 separate
  supports.
• E9C07 A terminating resistor on a rhombic
  antenna changes the radiation pattern from
  bidirectional to unidirectional.

unidirectional
bidirectional
31
Amateur Radio Extra ClassFeedlines Safety

• E9H04 Effective radiated power is the term that
  describes station output (including the
  transmitter, antenna and everything in between),
  when considering transmitter power and system
  gains and losses.
• E9H01 The effective radiated power of a repeater
  station with 150 watts transmitter power output,
  2-dB feed line loss, 2.2-dB duplexer loss and
  7-dBd antenna gain is 286 watts.
• E9H02 The effective radiated power of a repeater
  station with 200 watts transmitter power output,
  4-dB feed line loss, 3.2-dB duplexer loss, 0.8-dB
  circulator loss and 10-dBd antenna gain is 317
  watts.

ERP Power gain(s) Loss(es)
ERP 150 watts (7 dB) (2 dB 2.2 dB)
150 watts 2.8 dB
Gain/loss ratio 10(dB/10)or 10(2.8/10) or
10.28 or 1.905
ERP 150 watts x 1.905 (the overall db gain/loss
ratio)
285.8 watts
ERP Power gain(s) Loss(es)
ERP 200 watts (10 dB) (4 dB 3.2 dB 0.8
dB)
200 watts 2 dB
Gain/loss ratio 10(dB/10)or 10(2.0/10) or
10.20 or 1.584
ERP 200 watts x 1.584 (the overall db gain/loss
ratio)
316.9 watts
32
Amateur Radio Extra ClassFeedlines Safety

• E9H03 The effective radiated power of a repeater
  station with 200 watts transmitter power output,
  2-dB feed line loss, 2.8-dB duplexer loss, 1.2-dB
  circulator loss and 7-dBd antenna gain is 252
  watts.
• E9H04 Effective radiated power is the term that
  describes station output (including the
  transmitter, antenna and everything in between),
  when considering transmitter power and system
  gains and losses.
• E9D01 The gain of a parabolic dish antenna
  increases 6 dB when the operating frequency is
  doubled.

ERP Power gain(s) Loss(es)
ERP 200 watts (7 dB) (2 dB 2.8 dB 1.2 dB)
ERP 200 watts 1 dB
Gain/loss ratio 10(dB/10) or 10(1/10) or
10.1 or 1.258
ERP 200 watts x 1.258 (the overall db
gain/loss ratio)
251.7 watts
33
Amateur Radio Extra ClassFeedlines Safety

• E9D03 The beamwidth of an antenna decreases as
  the gain is increased.
• E9D04 It desirable for a ground-mounted
  satellite communications antenna system to be
  able to move in both azimuth and elevation in
  order to track the satellite as it orbits the
  earth.
• E0A11 Injuries from radiation (RF) leaks that
  exceed the MPE limits are considered a
  significant hazard when operating a klystron or
  cavity magnetron transmitter.
• E0A10 PCBs (Polychlorinated biphenyls) are
  found in some electronic components, such as
  high-voltage capacitors and transformers, are
  considered toxic.
• E0A05 One of the potential hazards of using
  microwaves in the amateur radio bands is the high
  gain antennas commonly used can result in high
  exposure levels.

The antenna becomes more directional
34
Amateur Radio Extra ClassFeedlines Safety

• E0A03 A practical way to estimate whether the RF
  fields produced by an amateur radio station are
  within permissible MPE limits would be to use a
  computer-based antenna modeling program to
  calculate field strength at accessible locations.
  
• E0A08 SAR (Specific Absorption Rate) is a
  measure of the rate at which RF energy is
  absorbed by the body.
• E0A02 When evaluating exposure levels from your
  station at a neighbors home, you must make sure
  signals from your station are less than the
  uncontrolled MPE limits.
• E0A06 There are separate electric (E) and
  magnetic (H) field MPE limits because

Ground reflections and scattering make the field
impedance vary with location.
E field and H field radiation intensity peaks
can occur at different locations.
35
Amateur Radio Extra ClassFeedlines Safety

• E9C13 When constructing a Beverage antenna, to
  achieve good performance at the desired frequency
  it should be one or more wavelengths long.
• E9H09 A receiving loop antenna is an antenna
  made of one or more turns of wire wound in the
  shape of a large open coil.
• E9H10 The output voltage of a receiving loop
  antenna can be increased by increasing either the
  number of wire turns in the loop or the area of
  the loop structure.

36
Amateur Radio Extra ClassFeedlines Safety

• E9H11 A cardioid pattern is desirable for a
  direction-finding system because response
  characteristics of the cardioid pattern can
  assist in determining the direction of the
  desired station.
• E9H12 An advantage of using a shielded loop
  antenna for direction finding is that it is
  electro-statically balanced against ground,
  giving better nulls.

Two ¼ wave vertical antennas fed 90-degrees out
of phase will produce a cardioid radiation
pattern. Deep null will be 180 degrees from
signal being received.
37
Amateur Radio Extra ClassFeedlines Safety

• E9H05 The main drawback of a wire-loop antenna
  for direction finding is that it has a
  bidirectional pattern.
• E9H07 An RF attenuator is desirable in a
  receiver used for direction finding because it
  prevents receiver overload from extremely strong
  signals.

38
Amateur Radio Extra ClassFeedlines Safety

• E9H08 The function of a sense antenna is that it
  modifies the pattern of a DF antenna array to
  provide a null in one direction.
• E9H06 The triangulation method of direction
  finding is when antenna headings from several
  different receiving stations are used to locate
  the signal source.

Ferrite-core bar antenna and vertical rod sense
antenna.
39
Element 4 Extra Class Question Pool
Feedlines and Safety
Valid July 1, 2008 Through June 30, 2012
40
E9E01 What system matches 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 each
side of element center?

• The gamma matching system
• The delta matching system
• The omega matching system
• The stub matching system

41
E9E02 What is the name of an antenna matching
system that matches an unbalanced feed line to an
antenna by feeding the driven element both at the
center of the element and at a fraction of a
wavelength to one side of center?

1. The gamma match
2. The delta match
3. The omega match
4. The stub match

42
E9E03 What is the name of the matching system
that uses a short perpendicular section of
transmission line connected to the feed line near
the antenna?

• A. The gamma match
• B. The delta match
• C. The omega match
• D. The stub match

43
E9E04 What is the purpose of the series
capacitor in a gamma-type antenna matching
network?

1. To provide DC isolation between the feed-line and
   the antenna
2. To compensate for the inductive reactance of the
   matching network
3. To provide a rejection notch to prevent the
   radiation of harmonics
4. To transform the antenna impedance to a higher
   value

44
E9E05 How must the driven element in a 3-element
Yagi be tuned to use a hairpin matching system?

1. The driven element reactance must be capacitive
2. The driven element reactance must be inductive
3. The driven element resonance must be lower than
   the operating frequency
4. The driven element radiation resistance must be
   higher than the characteristic impedance of the
   transmission line

45
E9E06 What is the equivalent lumped-constant
network for a hairpin matching system on a
3-element Yagi?

1. Pi network
2. Pi-L network
3. L network
4. Parallel-resonant tank

46
E9E07 What parameter best describes the
interactions at the load end of a mismatched
transmission line?

1. Characteristic impedance
2. Reflection coefficient
3. Velocity factor
4. Dielectric Constant

47
E9E08 Which of the following measurements
describes a mismatched transmission line?

1. An SWR less than 11
2. A reflection coefficient greater than 1
3. A dielectric constant greater than 1
4. An SWR greater than 11

48
E9E09 Which of these matching systems is an
effective method of connecting a 50-ohm coaxial
cable feed-line to a grounded tower so it can be
used as a vertical antenna?

1. Double-bazooka match
2. Hairpin match
3. Gamma match
4. All of these answers are correct

49
E9E10 Which of these choices is an effective way
to match an antenna with a 100-ohm terminal
impedance to a 50-ohm coaxial cable feed-line?

1. Connect a 1/4-wavelength open stub of 300-ohm
   twin-lead in parallel with the coaxial feed-line
   where it connects to the antenna
2. Insert a 1/2 wavelength piece of 300-ohm
   twin-lead in series between the antenna terminals
   and the 50-ohm feed cable
3. Insert a 1/4-wavelength piece of 75-ohm coaxial
   cable transmission line in series between the
   antenna terminals and the 50-ohm feed cable
4. Connect 1/2 wavelength shorted stub of 75-ohm
   cable in parallel with the 50-ohm cable where it
   attaches to the antenna

50
E9E11 What is an effective way of matching a
feed-line to a VHF or UHF antenna when the
impedances of both the antenna and feed-line are
unknown?

1. Use a 50-ohm 11 balun between the antenna and
   feed-line
2. Use the "universal stub" matching technique
3. Connect a series-resonant LC network across the
   antenna feed terminals
4. Connect a parallel-resonant LC network across the
   antenna feed terminals

51
E9E12 What is the primary purpose of a "phasing
line" when used with an antenna having multiple
driven elements?

1. It ensures that each driven element operates in
   concert with the others to create the desired
   antenna pattern
2. It prevents reflected power from traveling back
   down the feed-line and causing harmonic radiation
   from the transmitter
3. It allows single-band antennas to operate on
   other bands
4. It makes sure the antenna has a low-angle
   radiation pattern

52
E9E13 What is the purpose of a "Wilkinson
divider"?

1. It divides the operating frequency of a
   transmitter signal so it can be used on a lower
   frequency band
2. It is used to feed high-impedance antennas from a
   low-impedance source
3. It divides power equally among multiple loads
   while preventing changes in one load from
   disturbing power flow to the others
4. It is used to feed low-impedance loads from a
   high-impedance source

53
E9F08 What is the term for the ratio of the
actual speed at which a signal travels through a
transmission line to the speed of light in a
vacuum?

1. Velocity factor
2. Characteristic impedance
3. Surge impedance
4. Standing wave ratio

54
E9F01 What is the velocity factor of a
transmission line?

1. The ratio of the characteristic impedance of the
   line to the terminating impedance
2. The index of shielding for coaxial cable
3. The velocity of the wave in the transmission line
   multiplied by the velocity of light in a vacuum
4. The velocity of the wave in the transmission line
   divided by the velocity of light in a vacuum

55
E9F02 What determines the velocity factor in a
transmission line?

1. The termination impedance
2. The line length
3. Dielectric materials used in the line
4. The center conductor resistivity

56
E9F04 What is the typical velocity factor for a
coaxial cable with solid polyethylene dielectric?

1. 2.70
2. 0.66
3. 0.30
4. 0.10

57
E9F03 Why is the physical length of a coaxial
cable transmission line shorter than its
electrical length?

1. Skin effect is less pronounced in the coaxial
   cable
2. The characteristic impedance is higher in a
   parallel feed line
3. The surge impedance is higher in a parallel feed
   line
4. Electrical signals move more slowly in a coaxial
   cable than in air

58
E9F05 What is the physical length of a coaxial
transmission line that is electrically
one-quarter wavelength long at 14.1 MHz? (Assume
a velocity factor of 0.66.)

1. 20 meters
2. 2.3 meters
3. 3.5 meters
4. 0.2 meters

59
E9F06 What is the physical length of a parallel
conductor feed line that is electrically one-half
wavelength long at 14.10 MHz? (Assume a velocity
factor of 0.95.)

1. 15 meters
2. 20 meters
3. 10 meters
4. 71 meters

60
E9F07 What characteristic will 450-ohm ladder
line have at 50 MHz, as compared to
0.195-inch-diameter coaxial cable (such as RG-58)?

1. Lower loss
2. Higher SWR
3. Smaller reflection coefficient
4. Lower velocity factor

61
E9F09 What would be the physical length of a
typical coaxial transmission line that is
electrically one-quarter wavelength long at 7.2
MHz? (Assume a velocity factor of 0.66)

1. 10 meters
2. 6.9 meters
3. 24 meters
4. 50 meters

62
E9F10 What kind of impedance does a
1/8-wavelength transmission line present to a
generator when the line is shorted at the far end?

1. A capacitive reactance
2. The same as the characteristic impedance of the
   line
3. An inductive reactance
4. The same as the input impedance to the final
   generator stage

63
E9F11 What kind of impedance does a
1/8-wavelength transmission line present to a
generator when the line is open at the far end?

1. The same as the characteristic impedance of the
   line
2. An inductive reactance
3. A capacitive reactance
4. The same as the input impedance of the final
   generator stage

64
E9F12 What kind of impedance does a
1/4-wavelength transmission line present to a
generator when the line is open at the far end?

1. A very high impedance
2. A very low impedance
3. The same as the characteristic impedance of the
   line
4. The same as the input impedance to the final
   generator stage

65
E9F13 What kind of impedance does a
1/4-wavelength transmission line present to a
generator when the line is shorted at the far end?

1. A very high impedance
2. A very low impedance
3. The same as the characteristic impedance of the
   transmission line
4. The same as the generator output impedance

66
E9F14 What kind of impedance does a
1/2-wavelength transmission line present to a
generator when the line is shorted at the far end?

1. A very high impedance
2. A very low impedance
3. The same as the characteristic impedance of the
   line
4. The same as the output impedance of the generator

67
E9F15 What kind of impedance does a
1/2-wavelength transmission line present to a
generator when the line is open at the far end?

1. A very high impedance
2. A very low impedance
3. The same as the characteristic impedance of the
   line
4. The same as the output impedance of the generator

68
E9F16 What is the primary difference between
foam-dielectric coaxial cable as opposed to
solid-dielectric cable, assuming all other
parameters are the same?

1. Reduced safe operating voltage limits
2. Reduced losses per unit of length
3. Higher velocity factor
4. All of these answers are correct

69
E4A07 Which of the following is an advantage
of using an antenna analyzer vs. a SWR bridge to
measure antenna SWR?

1. Antenna analyzers automatically tune your antenna
   for resonance
2. Antenna analyzers typically do not need an
   external RF source
3. Antenna analyzers typically display a
   time-varying representation of the modulation
   envelope
4. All of these answers are correct

70
E4B12 How should a portable SWR analyzer be
connected when measuring antenna resonance and
feedpoint impedance?

1. Loosely couple the analyzer near the antenna base
2. Connect the analyzer via a high-impedance
   transformer to the antenna
3. Connect the antenna and a dummy load to the
   analyzer
4. Connect the antenna feed line directly to the
   analyzer's connector

71
E9G01 Which of the following can be calculated
using a Smith chart?

1. Impedance along transmission lines
2. Radiation resistance
3. Antenna radiation pattern
4. Radio propagation

72
E4A08 Which of the following instruments would
be best for measuring the SWR of a beam antenna?

1. A spectrum analyzer
2. A Q meter
3. An ohmmeter
4. An antenna analyzer

73
E9G02 What type of coordinate system is used in
a Smith chart?

1. Voltage circles and current arcs
2. Resistance circles and reactance arcs
3. Voltage lines and current chords
4. Resistance lines and reactance chords

74
E9G03 Which of the following is often
determined using a Smith chart?

1. Beam headings and radiation patterns
2. Satellite azimuth and elevation bearings
3. Impedance and SWR values in transmission lines
4. Trigonometric functions

75
E9G04 What are the two families of circles and
arcs that make up a Smith chart?

1. Resistance and voltage
2. Reactance and voltage
3. Resistance and reactance
4. Voltage and impedance

76
E9G05 What type of chart is shown in Figure
E9-3?

1. Smith chart
2. Free-space radiation directivity chart
3. Elevation angle radiation pattern chart
4. Azimuth angle radiation pattern chart

77
E9G06 On the Smith chart shown in Figure E9-3,
what is the name for the large outer circle on
which the reactance arcs terminate?

1. Prime axis
2. Reactance axis
3. Impedance axis
4. Polar axis

78
E9G07 On the Smith chart shown in Figure E9-3,
what is the only straight line shown?

1. The reactance axis
2. The current axis
3. The voltage axis
4. The resistance axis

79
E9G08 What is the process of normalization with
regard to a Smith chart?

1. Reassigning resistance values with regard to the
   reactance axis
2. Reassigning reactance values with regard to the
   resistance axis
3. Reassigning impedance values with regard to the
   prime center
4. Reassigning prime center with regard to the
   reactance axis

80
E9G09 What third family of circles is often
added to a Smith chart during the process of
solving problems?

1. Standing-wave ratio circles
2. Antenna-length circles
3. Coaxial-length circles
4. Radiation-pattern circles

81
E9G10 What do the arcs on a Smith chart
represent?

1. Frequency
2. SWR
3. Points with constant resistance
4. Points with constant reactance

82
E9G11 How are the wavelength scales on a Smith
chart calibrated?

1. In fractions of transmission line electrical
   frequency
2. In fractions of transmission line electrical
   wavelength
3. In fractions of antenna electrical wavelength
4. In fractions of antenna electrical frequency

83
E9C04 Which of the following describes a basic
rhombic antenna?

1. Unidirectional four-sided, each side one
   quarter-wavelength long terminated in a
   resistance equal to its characteristic impedance
2. Bidirectional four-sided, each side one or more
   wavelengths long open at the end opposite the
   transmission line connection
3. Four-sided an LC network at each corner except
   for the transmission connection
4. Four-sided, each side of a different physical
   length

84
E9C05 What are the main advantages of a
terminated rhombic antenna?

1. Wide frequency range, high gain and high
   front-to-back ratio
2. High front-to-back ratio, compact size and high
   gain
3. Unidirectional radiation pattern, high gain and
   compact size
4. Bidirectional radiation pattern, high gain and
   wide frequency range

85
E9C06 What are the disadvantages of a terminated
rhombic antenna for the HF bands?

1. The antenna has a very narrow operating bandwidth
2. The antenna produces a circularly polarized
   signal
3. The antenna requires a large physical area and 4
   separate supports
4. The antenna is more sensitive to man-made static
   than any other type

86
E9C07 What is the effect of a terminating
resistor on a rhombic antenna?

1. It reflects the standing waves on the antenna
   elements back to the transmitter
2. It changes the radiation pattern from
   bidirectional to unidirectional
3. It changes the radiation pattern from horizontal
   to vertical polarization
4. It decreases the ground loss

87
E9H04 What term describes station output
(including the transmitter, antenna and
everything in between), when considering
transmitter power and system gains and losses?

1. Power factor
2. Half-power bandwidth
3. Effective radiated power
4. Apparent power

88
E9H01 What is the effective radiated power of a
repeater station with 150 watts transmitter power
output, 2-dB feed line loss, 2.2-dB duplexer loss
and 7-dBd antenna gain?

1. 1977 watts
2. 78.7 watts
3. 420 watts
4. 286 watts

89
E9H02 What is the effective radiated power of a
repeater station with 200 watts transmitter power
output, 4-dB feed line loss, 3.2-dB duplexer
loss, 0.8-dB circulator loss and 10-dBd antenna
gain?

1. 317 watts
2. 2000 watts
3. 126 watts
4. 300 watts

90
E9H03 What is the effective radiated power of a
repeater station with 200 watts transmitter power
output, 2-dB feed line loss, 2.8-dB duplexer
loss, 1.2-dB circulator loss and 7-dBd antenna
gain?

1. 159 watts
2. 252 watts
3. 632 watts
4. 63.2 watts

91
E0A04 When evaluating a site with multiple
transmitters operating at the same time, the
operators and licensees of which transmitters are
responsible for mitigating over-exposure
situations?

1. Only the most powerful transmitter
2. Only commercial transmitters
3. Each transmitter that produces 5 or more of its
   maximum permissible exposure limit at accessible
   locations
4. Each transmitter operating with a duty-cycle
   greater than 50

92
E9D01 How does the gain of a parabolic dish
antenna change when the operating frequency is
doubled?

1. Gain does not change
2. Gain is multiplied by 0.707
3. Gain increases 6 dB
4. Gain increases 3 dB

93
E9D03 How does the beamwidth of an antenna vary
as the gain is increased?

1. It increases geometrically
2. It increases arithmetically
3. It is essentially unaffected
4. It decreases

94
E9D04 Why is it desirable for a ground-mounted
satellite communications antenna system to be
able to move in both azimuth and elevation?

1. In order to track the satellite as it orbits the
   earth
2. So the antenna can be pointed away from
   interfering signals
3. So the antenna can be positioned to cancel the
   effects of Faraday rotation
4. To rotate antenna polarization to match that of
   the satellite

95
E0A11 Which of these items might be a significant
hazard when operating a klystron or cavity
magnetron transmitter?

1. Hearing loss caused by high voltage corona
   discharge
2. Blood clotting from the intense magnetic field
3. Injury from radiation leaks that exceed the MPE
   limits
4. Ingestion of ozone gas from the cooling system

96
E0A10 What material found in some electronic
components such as high-voltage capacitors and
transformers is considered toxic?

1. Polychlorinated biphenyls
2. Polyethylene
3. Polytetrafluroethylene
4. Polymorphic silicon

97
E0A05 What is one of the potential hazards of
using microwaves in the amateur radio bands?

1. Microwaves are ionizing radiation
2. The high gain antennas commonly used can result
   in high exposure levels
3. Microwaves often travel long distances by
   ionospheric reflection
4. The extremely high frequency energy can damage
   the joints of antenna structures

98
E0A03 Which of the following would be a practical
way to estimate whether the RF fields produced by
an amateur radio station are within permissible
MPE limits?

1. Use a calibrated antenna analyzer
2. Use a hand calculator plus Smith-chart equations
   to calculate the fields
3. Walk around under the antennas with a neon-lamp
   probe to find the strongest fields
4. Use a computer-based antenna modeling program to
   calculate field strength at accessible locations

99
E0A08 What does SAR measure?

1. Synthetic Aperture Ratio of the human body
2. Signal Amplification Rating
3. The rate at which RF energy is absorbed by the
   body
4. The rate of RF energy reflected from stationary
   terrain

100
E0A02 When evaluating exposure levels from your
station at a neighbors home, what must you do?

1. Make sure signals from your station are less than
   the controlled MPE limits
2. Make sure signals from your station are less than
   the uncontrolled MPE limits
3. Nothing you need only evaluate exposure levels
   on your own property
4. Advise your neighbors of the results of your tests

101
E0A06 Why are there separate electric (E) and
magnetic (H) field MPE limits?

1. The body reacts to electromagnetic radiation from
   both the E and H fields
2. Ground reflections and scattering make the field
   impedance vary with location
3. E field and H field radiation intensity peaks can
   occur at different locations
4. All of these answers are correct

102
E9C13 When constructing a Beverage antenna, which
of the following factors should be included in
the design to achieve good performance at the
desired frequency?

1. Its overall length must not exceed 1/4 wavelength
2. It must be mounted more than 1 wavelength above
   ground
3. It should be configured as a four-sided loop
4. It should be one or more wavelengths long

103
E9H09 What is a receiving loop antenna?

1. A large circularly-polarized antenna
2. A small coil of wire tightly wound around a
   toroidal ferrite core
3. One or more turns of wire wound in the shape of a
   large open coil
4. Any antenna coupled to a feed line through an
   inductive loop of wire

104
E9H10 How can the output voltage of a receiving
loop antenna be increased?

1. By reducing the permeability of the loop shield
2. By increasing the number of wire turns in the
   loop and reducing the area of the loop structure
3. By reducing either the number of wire turns in
   the loop or the area of the loop structure
4. By increasing either the number of wire turns in
   the loop or the area of the loop structure

105
E9H11 Why is an antenna with a cardioid pattern
desirable for a direction-finding system?

1. The broad-side responses of the cardioid pattern
   can be aimed at the desired station
2. The response characteristics of the cardioid
   pattern can assist in determining the direction
   of the desired station
3. The extra side lobes in the cardioid pattern can
   pinpoint the direction of the desired station
4. The high-radiation angle of the cardioid pattern
   is useful for short-distance direction finding

106
E9H12 What is an advantage of using a shielded
loop antenna for direction finding?

1. It automatically cancels ignition noise pickup in
   mobile installations
2. It is electro-statically balanced against ground,
   giving better nulls
3. It eliminates tracking errors caused by strong
   out-of-band signals
4. It allows stations to communicate without giving
   away their position

107
E9H05 What is the main drawback of a wire-loop
antenna for direction finding?

1. It has a bidirectional pattern
2. It is non-rotatable
3. It receives equally well in all directions
4. It is practical for use only on VHF bands

108
E9H07 Why is an RF attenuator desirable in a
receiver used for direction finding?

1. It narrows the bandwidth of the received signal
2. It eliminates the effects of isotropic radiation
3. It reduces loss of received signals caused by
   antenna pattern nulls
4. It prevents receiver overload from extremely
   strong signals

109
E9H08 What is the function of a sense antenna?

1. It modifies the pattern of a DF antenna array to
   provide a null in one direction
2. It increases the sensitivity of a DF antenna
   array
3. It allows DF antennas to receive signals at
   different vertical angles
4. It provides diversity reception that cancels
   multipath signals

110
E9H06 What is the triangulation method of
direction finding?

1. The geometric angle of sky waves from the source
   are used to determine its position
2. A fixed receiving station plots three headings
   from the signal source on a map
3. Antenna headings from several different receiving
   stations are used to locate the signal source
4. A fixed receiving station uses three different
   antennas to plot the location of the signal source