1. Technician License Class
Propagation, Antennas and
Feed Lines

2. Propagation Radio waves travel in straight lines. Except: Reflection.
Bouncing off reflective surface.
Refraction.
Gradual bending while traveling through atmosphere.
Diffraction.
Bending around edge of solid object.

3. Propagation Radio waves travel in straight lines. Line-of-sight.
Radio horizon.
Distance at which radio signals are blocked by curvature of the earth.
Slightly greater than optical horizon.
Refraction increases radio horizon by about 15%.

4. Propagation
Diffraction.

5. Propagation Multi-path.
Radio waves reflected off of many objects arrive at receive antenna at different times.
Picket fencing.

6. Propagation Radio waves can pass through openings in solid objects.
Longest dimension of opening at least 1/2λ.
Because of shorter wavelength, UHF signals can pass through buildings better than VHF signals.

7. Propagation Tropospheric Ducting
Radio waves can travel for long distances along boundaries of different temperature air layers.
Propagation of 300 miles or more on VHF or UHF.

8. Change the batteries in your radio to a different type
T3A01 -- What should you do if another operator reports that your station’s 2 meter signals were strong just a moment ago, but now they are weak or distorted?
Change the batteries in your radio to a different type
Turn on the CTCSS tone
Ask the other operator to adjust his squelch control
Try moving a few feet or changing the direction of your antenna if possible, as reflections may be causing multi-path distortion

9. VHF signals lose power faster over distance
T3A02 -- Why are UHF signals often more effective from inside buildings than VHF signals?
VHF signals lose power faster over distance
The shorter wavelength allows them to more easily penetrate the structure of buildings
This is incorrect; VHF works better than UHF inside buildings
UHF antennas are more efficient than VHF antennas

10. Flip-flopping Picket fencing Frequency shifting Pulsing
T3A06 -- What term is commonly used to describe the rapid fluttering sound sometimes heard from mobile stations that are moving while transmitting?
Flip-flopping
Picket fencing
Frequency shifting
Pulsing

11. Frequency shift due to Faraday rotation
T3A08 -- Which of the following is a likely cause of irregular fading of signals received by ionospheric reflection?
Frequency shift due to Faraday rotation
Interference from thunderstorms
Random combining of signals arriving via different paths
Intermodulation distortion

12. Knife-edge diffraction Faraday rotation Quantum tunneling
T3C05 -- Which of the following effects might cause radio signals to be heard despite obstructions between the transmitting and receiving stations?
Knife-edge diffraction
Faraday rotation
Quantum tunneling
Doppler shift

13. Tropospheric scatter D layer refraction F2 layer refraction
T3C06 -- What mode is responsible for allowing over-the-horizon VHF and UHF communications to ranges of approximately 300 miles on a regular basis?
Tropospheric scatter
D layer refraction
F2 layer refraction
Faraday rotation

14. T3C08 -- What causes tropospheric ducting?
Discharges of lightning during electrical storms
Sunspots and solar flares
Updrafts from hurricanes and tornadoes
Temperature inversions in the atmosphere

15. T3C10 -- What is the radio horizon?
The distance over which two stations can communicate by direct path
The distance from the ground to a horizontally mounted antenna
The farthest point you can see when standing at the base of your antenna tower
The shortest distance between two points on the Earth's surface

16. Radio signals move somewhat faster than the speed of light
T3C11 -- Why do VHF and UHF radio signals usually travel somewhat farther than the visual line of sight distance between two stations?
Radio signals move somewhat faster than the speed of light
Radio waves are not blocked by dust particles
The Earth seems less curved to radio waves than to light
Radio waves are blocked by dust particles

17. Propagation The Ionosphere.
The upper layers of the atmosphere are ionized by UV radiation from the sun.
30 to 260 miles above the surface.

18. Propagation The Ionosphere.
The ionosphere is divided into layers or regions.
Each layer has unique characteristics.

19. Propagation The Ionosphere.
Some radio frequency ranges (HF & lower VHF frequencies) will be reflected off of the ionosphere & return to earth.
Called “skip”.
Distances well beyond the range of line-of-sight.
Several hundred to several thousand miles.
Maximum of about 2500 miles for a single hop.
Can have multiple hops.

20. Propagation The Ionosphere.
The higher the amount of ionization, the better radio waves are reflected off of the ionosphere.
Amount of ionization varies with time of day.
Sunrise to sunset  higher ionization level.
Amount of ionization varies with sunspot activity.
More sunspots  higher ionization level.
Larger sunspots  higher ionization level.
Number & size of sunspots varies over an 11-year cycle.
Currently in declining portion of Cycle 24.

21. Propagation
The Ionosphere.

22. Propagation The Ionosphere.
Skip is not really reflection (bouncing) but rather refraction (bending).
The shorter the wavelength (higher frequency), the less the signal is refracted (bent).
At some frequency, the wave is no longer bent enough to return to earth.
Critical frequency.
Skip normally occurs in the F-layer (F1 & F2).
Can occur in the E-layer.

23. Propagation The Ionosphere.
The highest frequency that can be used to communicate between 2 points is called the Maximum Useable Frequency (MUF).
The lowest frequency that can be used to communicate between 2 points is called the Lowest Useable Frequency (LUF).
MUF & LUF vary depending on amount of ionization of the ionosphere.

24. Propagation
The Ionosphere.

25. Propagation The Ionosphere. E-Layer Propagation. Sporadic-E. Aurora.
Any time during solar cycle.
Early summer & mid-winter
10m, 6m, & 2m.
Aurora.
Rapid signal strength changes.
Sounds fluttery or distorted.
Primarily 6m.
Meteor scatter.

26. Propagation The Ionosphere.
The lowers regions of the ionosphere absorb radio waves.
Primarily D-layer.
Some absorption in E-layer.
The longer the wavelength (lower frequency), the more absorption.

27. The stratosphere The troposphere The ionosphere The magnetosphere
T3A11 -- Which part of the atmosphere enables the propagation of radio signals around the world?
The stratosphere
The troposphere
The ionosphere
The magnetosphere

28. They are too weak to go very far
T3C01 -- Why are direct (not via a repeater) UHF signals rarely heard from stations outside your local coverage area?
They are too weak to go very far
FCC regulations prohibit them from going more than 50 miles
UHF signals are usually not reflected by the ionosphere
They collide with trees and shrubbery and fade out

29. Signals are being reflected from outer space
T3C02 -- Which of the following might be happening when VHF signals are being received from long distances?
Signals are being reflected from outer space
Signals are arriving by sub-surface ducting
Signals are being reflected by lightning storms in your area
Signals are being refracted from a sporadic E layer

30. Signals from distances of 10,000 or more miles are common
T3C03 (B)-- What is a characteristic of VHF signals received via auroral reflection?
Signals from distances of 10,000 or more miles are common
The signals exhibit rapid fluctuations of strength and often sound distorted
These types of signals occur only during winter nighttime hours
These types of signals are generally strongest when your antenna is aimed west

31. Gray-line propagation
T3C04 -- Which of the following propagation types is most commonly associated with occasional strong over-the-horizon signals on the 10, 6, and 2 meter bands?
Backscatter
Sporadic E
D layer absorption
Gray-line propagation

32. 10 meters 6 meters 2 meters 70 cm
T3C07 -- What band is best suited for communicating via meteor scatter?
10 meters
6 meters
2 meters
70 cm

33. T3C09 -- What is generally the best time for long-distance 10 meter band propagation via the F layer?
From dawn to shortly after sunset during periods of high sunspot activity
From shortly after sunset to dawn during periods of high sunspot activity
From dawn to shortly after sunset during periods of low sunspot activity
From shortly after sunset to dawn during periods of low sunspot activity

34. All of these choices are correct
T3C12 -- Which of the following bands may provide long distance communications during the peak of the sunspot cycle?
Six or ten meters
23 centimeters
70 centimeters or 1.25 meters
All of these choices are correct

35. Antenna Fundamentals Definitions:
Antenna: Converts an RF electrical signal into an electromagnetic wave (radio wave) or vice versa.
Any electrical conductor can act as an antenna.
Some sizes & configurations work better than others.
Feed-line: Conducts the RF electrical signal to/from the antenna.
a.k.a. – Transmission Line.

36. Antenna Fundamentals Definitions:
Feed Point: Place where the feed-line is connected to antenna.
Feed Point Impedance: Ratio of RF voltage to RF current at the feed point.
If impedance is pure resistance (no reactance) then antenna is said to be “resonant”

37. Antenna Fundamentals Definitions:
Antenna Elements: Conductive parts of an antenna.
Driven Element: Element that feed-line is connected to.
Driven Array: More than one driven element.
Parasitic Element(s): Element(s) not directly connected to feed-line.

38. Antenna Fundamentals Polarization.
An electromagnetic wave consists of an electric wave & a magnetic wave at right angles to each other.
Polarization is the orientation of the electric wave with respect to the earth.

39. Antenna Fundamentals Polarization.
If electric wave is horizontal (parallel to the ground), then wave is said to be horizontally polarized.
If electric wave is vertical (perpendicular to the ground), then wave is said to be vertically polarized.

40. Antenna Fundamentals
Polarization.

41. Antenna Fundamentals Polarization.
The direction of the electric field is the same as the direction of the antenna element.
Loop antennas & circular polarization are exceptions.
If polarizations are not matched, reduced signal strength results.
Polarization of sky wave signals (skip) is random & continuously changing.
Elliptically polarized.
Any polarization antenna may be used.

42. The modulation sidebands might become inverted
T3A04 -- What can happen if the antennas at opposite ends of a VHF or UHF line of sight radio link are not using the same polarization?
The modulation sidebands might become inverted
Signals could be significantly weaker
Signals have an echo effect on voices
Nothing significant will happen

43. Electromagnetic Electrostatic Surface acoustic Magnetostrictive
T3A07 -- What type of wave carries radio signals between transmitting and receiving stations?
Electromagnetic
Electrostatic
Surface acoustic
Magnetostrictive

44. Digital modes are unusable
T3A09 -- Which of the following results from the fact that skip signals refracted from the ionosphere are elliptically polarized?
Digital modes are unusable
Either vertically or horizontally polarized antennas may be used for transmission or reception
FM voice is unusable
Both the transmitting and receiving antennas must be of the same polarization

45. The orientation of the electric field
T3B02 -- What property of a radio wave is used to describe its polarization?
The orientation of the electric field
The orientation of the magnetic field
The ratio of the energy in the magnetic field to the energy in the electric field
The ratio of the velocity to the wavelength

46. T3B03 -- What are the two components of a radio wave?
AC and DC
Voltage and current
Electric and magnetic fields
Ionizing and non-ionizing radiation

47. Gravity waves Sound waves Radio waves Pressure waves
T5C07 -- What is a usual name for electromagnetic waves that travel through space?
Gravity waves
Sound waves
Radio waves
Pressure waves

48. T9A02 -- Which of the following is true regarding vertical antennas?
The magnetic field is perpendicular to the Earth
The electric field is perpendicular to the Earth
The phase is inverted
The phase is reversed

49. Antenna Fundamentals Decibels.
The difference in strength between 2 signals is often expressed in decibels (dB).
Ratio between 2 values
Logarithmic scale.

50. Antenna Fundamentals Decibels. Commonly used to:
Specify gain of an amplifier.
Specify gain of an antenna.
Specify loss in a feed line.

51. Antenna Fundamentals Decibels. dB = 10 log10(P1/P2)
Ratio between 2 values
One value is often a standard reference value.
Logarithmic scale.
Power ratio:
dB = 10 log10(P1/P2)

52. Antenna Fundamentals dB Ratio 1.000 -1 0.794 -2 0.631 -3 0.501 -4
1.000 -1
0.794 -2
0.631 -3
0.501 -4
0.398 -5
0.316 -6
0.250 -7
0.200 -8
0.159 -9
0.126
-10
0.100 dB
Ratio
1.000 1
1.259 2
1.585 3
1.995 4
2.512 5
3.162 6
4.000 7
5.012 8
6.310 9
7.943 10
10.00

53. T5B09 -- What is the approximate amount of change, measured in decibels (dB), of a power increase from 5 watts to 10 watts?
2 dB
3 dB
5 dB
10 dB

54. T5B10 -- What is the approximate amount of change, measured in decibels (dB), of a power decrease from 12 watts to 3 watts?
-1 dB
-3 dB
-6 dB
-9 dB

55. T5B11 -- What is the approximate amount of change, measured in decibels (dB), of a power increase from 20 watts to 200 watts?
10 dB
12 dB
18 dB
28 dB

56. Antenna Fundamentals Antenna Gain.
Omni-directional antennas radiate equally in all directions.
Directional antennas focus radiation in one or more specific directions.
a.k.a. – Beam antennas.
Gain is the apparent increase in power in a particular direction because energy is focused in that direction.
Measured in decibels (dB)

57. Antenna Fundamentals Radiation Patterns.
A way of visualizing antenna performance.
The further the line is away from the center of the graph, the stronger the signal in that direction.

58. Antenna Fundamentals
Radiation Patterns.

59. T9A11 -- What is meant by the gain of an antenna?
The additional power that is added to the transmitter power
The additional power that is lost in the antenna when transmitting on a higher frequency
The increase in signal strength in a specified direction when compared to a reference antenna
The increase in impedance on receive or transmit compared to a reference antenna

60. Feed Lines and SWR Feed Lines. Feed lines are used for:
Connecting RF signals between radio and antenna.
Connecting RF signals between pieces of equipment.
Feed lines are constructed using special materials and configurations.
Maintain constant impedance.
Minimize losses.

61. Feed Lines and SWR Feed Lines. Coaxial cable.
Usually shortened to “coax”.
Most popular type.
Easy to work with.
Low characteristic impedance.
Typically 50Ω or 75Ω.
Moderate to high loss.
Loss varies with frequency.
Higher frequency  higher loss.

62. Feed Lines and SWR Feed Lines. Coaxial cable.
Energy lost in feed line is converted to heat.
Loss is primarily determined by size of cable & by insulating material.
Larger diameter  Lower loss.
Air is lowest loss insulator.
Foam dielectric coax has lower loss than solid dielectric coax because it has more air.
Air-insulated hard line.

63. Feed Lines and SWR Feed Lines. Parallel-wire transmission line.
Open-wire line, window line, twin lead.
More difficult to work with.
High characteristic impedance.
Typically 300Ω to 600Ω.
Very low loss.

64. Feed Lines and SWR Characteristic Impedance.
Every transmission line has a characteristic impedance.
Measure of how RF energy flows down the line.
NOT the same as the ohmic resistance of the conductors that make up the line.

65. Feed Lines and SWR Characteristic Impedance. Coaxial cable.
Characteristic impedance primarily determined by ratio of diameter of shield to diameter of center conductor.
Larger ratio  higher impedance.
50Ω = RG-8, RG-8X, RG-58, RG-174.
75Ω = RG-6, RG-11, RG-59.

66. Feed Lines and SWR Characteristic Impedance.
Parallel-wire transmission line.
Characteristic impedance determined by ratio of diameter of conductors to distance between them.
Larger distance  higher impedance.
Smaller diameter  higher impedance.

67. T7C07 -- What happens to power lost in a feed line?
It increases the SWR
It comes back into your transmitter and could cause damage
It is converted into heat
It can cause distortion of your signal

68. T7C12 -- Which of the following is a common use of coaxial cable?
Carrying dc power from a vehicle battery to a mobile radio
Carrying RF signals between a radio and antenna
Securing masts, tubing, and other cylindrical objects on towers
Connecting data signals from a TNC to a computer

69. T9B02 -- What is the impedance of the most commonly used coaxial cable in typical amateur radio installations?
8 ohms
50 ohms
600 ohms
12 ohms

70. It is easy to use and requires few special installation considerations
T9B03 -- Why is coaxial cable used more often than any other feed line for amateur radio antenna systems?
It is easy to use and requires few special installation considerations
It has less loss than any other type of feed line
It can handle more power than any other type of feed line
It is less expensive than any other types of feed line

71. The apparent SWR increases The reflected power increases
T9B05 -- What generally happens as the frequency of a signal passing through coaxial cable is increased?
The apparent SWR increases
The reflected power increases
The characteristic impedance increases
The loss increases

72. Multi-conductor unbalanced cable Air-insulated hard line
T9B11 -- Which of the following types of feed line has the lowest loss at VHF and UHF?
50-ohm flexible coax
Multi-conductor unbalanced cable
Air-insulated hard line
75-ohm flexible coax

73. Break

74. Feed Lines and SWR Standing Wave Ratio (SWR).
If feed line impedance = antenna impedance:
All energy is delivered to the antenna.
Prefect match.
SWR = 1:1.
If feed line impedance ≠ antenna impedance:
Some energy reflected back towards the source.
Reflected energy often lost as heat.
SWR = ZLine / ZAnt or SWR = ZAnt / ZLine

75. Feed Lines and SWR Standing Wave Ratio (SWR).
Rule-of-thumb guidelines:
1:1 = Perfect.
2:1 = Acceptable.
Most modern transmitters will automatically reduce transmitter output power when SWR is above 2:1.
2:1 to 3:1= Useable (with tuner).
Many transceivers have an internal antenna tuner which will match SWR’s up to 3:1.
3:1 or more = Really bad.

76. T7C03 -- What, in general terms, is standing wave ratio (SWR)?
A measure of how well a load is matched to a transmission line
The ratio of high to low impedance in a feed line
The transmitter efficiency ratio
An indication of the quality of your station’s ground connection

77. T7C04 -- What reading on an SWR meter indicates a perfect impedance match between the antenna and the feed line?
2 to 1
1 to 3
1 to 1
10 to 1

78. T7C05 -- What is the approximate SWR value above which the protection circuits in most solid-state transmitters begin to reduce transmitter power?
2 to 1
1 to 2
6 to 1
10 to 1

79. T7C06 -- What does an SWR reading of 4:1 indicate?
Loss of -4dB
Good impedance match
Gain of +4dB
Impedance mismatch

80. To reduce television interference
T9B01 -- Why is it important to have a low SWR in an antenna system that uses coaxial cable feed line?
To reduce television interference
To allow the efficient transfer of power and reduce losses
To prolong antenna life
All of these choices are correct

81. T9B09 -- What might cause erratic changes in SWR readings?
The transmitter is being modulated
A loose connection in an antenna or a feed line
The transmitter is being over-modulated
Interference from other stations is distorting your signal

82. Practical Antenna Systems
Dipoles and Ground Planes.
Dipole.
Most basic antenna.
Two conductors, equal length.
Feed line connected in the middle.
Total length is 1/2 wavelength (1/2 λ).
Length (feet) = 468 / Frequency (MHz).

83. Practical Antenna Systems
Dipoles and Ground Planes.
Dipole.

84. Practical Antenna Systems
Dipoles and Ground Planes.
Dipole.

85. Practical Antenna Systems
Dipoles and Ground Planes.
Dipole.

86. Practical Antenna Systems
Dipoles and Ground Planes.
Ground Plane.
One half of a dipole that is oriented perpendicular to the Earth’s surface.
Other half of the dipole is replaced by a ground-plane.
Earth
Car roof, trunk lid, or other metal surface.
Radial wires.
Length (feet) = 234 / Frequency (MHz).
Omni-directional.

87. Practical Antenna Systems
Dipoles and Ground Planes.
Ground Plane.

88. Practical Antenna Systems
Dipoles and Ground Planes.
Ground Plane.

89. Practical Antenna Systems
Dipoles and Ground Planes.
Mobile antennas.
Most mobile antennas are a variation of the ground plane.
If antenna cannot be a full 1/4λ long, an inductor (coil) is added to make antenna electrically longer.
Mounting antenna in center of roof gives most uniform radiation pattern.

90. Practical Antenna Systems
Dipoles and Ground Planes.
Mobile antennas.
A popular mobile antenna for VHF & UHF is the 5/8λ vertical.
Lower angle of radiation.
Provides a gain of 1.5 dB over a 1/4λ vertical.

91. Practical Antenna Systems
Dipoles and Ground Planes.
“Rubber Duck” Antennas.
Variation of the ground-plane.
Commonly used on hand-held transceivers.
Coil of wire enclosed in rubber (plastic) covering.
Shorter than normal ground-plane.
Much less efficient than full-sized ground-plane.
Side note: Using a rubber duck antenna inside your vehicle is not a good idea because….
Signals are weaker due to shielding by car body.

92. Practical Antenna Systems
Loop Antennas.
Loop of wire.
Circumference is one wavelength (1λ) long.
Circular, triangular (delta), or square (quad).
Mounted vertically or horizontally.
If mounted vertically, can be either vertically or horizontally polarized.

93. A horizontally polarized antenna A rhombic antenna
T9A03 -- Which of the following describes a simple dipole mounted so the conductor is parallel to the Earth's surface?
A ground wave antenna
A horizontally polarized antenna
A rhombic antenna
A vertically polarized antenna

94. It does not transmit or receive as effectively as a full-sized antenna
T9A04 -- What is a disadvantage of the “rubber duck” antenna supplied with most handheld radio transceivers?
It does not transmit or receive as effectively as a full-sized antenna
It transmits a circularly polarized signal
If the rubber end cap is lost it will unravel very quickly
All of these choices are correct

95. Insert coils in series with radiating wires Shorten it
T9A05 -- How would you change a dipole antenna to make it resonant on a higher frequency?
Lengthen it
Insert coils in series with radiating wires
Shorten it
Add capacitive loading to the ends of the radiating wires

96. It might cause your radio to overheat
T9A07 -- What is a good reason not to use a “rubber duck” antenna inside your car?
Signals can be significantly weaker than when it is outside of the vehicle
It might cause your radio to overheat
The SWR might decrease, decreasing the signal strength
All of these choices are correct

97. T9A08 -- What is the approximate length, in inches, of a quarter-wavelength vertical antenna for 146 MHz?
112 50 19 12

98. T9A09 -- What is the approximate length, in inches, of a 6 meter 1/2-wavelength wire dipole antenna?50
112
236

99. Equally in all directions Off the ends of the antenna
T9A10 -- In which direction is the radiation strongest from a half-wave dipole antenna in free space?
Equally in all directions
Off the ends of the antenna
Broadside to the antenna
In the direction of the feed line

100. T9A12 -- What is a reason to use a properly mounted 5/8 wavelength antenna for VHF or UHF mobile service?
It offers a lower angle of radiation and more gain than a 1/4 wavelength antenna and usually provides improved coverage
It features a very high angle of radiation and is better for communicating via a repeater
The 5/8 wavelength antenna completely eliminates distortion caused by reflected signals
The 5/8 wavelength antenna offers a 10-times power gain over a 1/4 wavelength design

101. Roof mounts have the lowest possible SWR of any mounting configuration
T9A13 -- Why are VHF or UHF mobile antennas often mounted in the center of the vehicle roof?
Roof mounts have the lowest possible SWR of any mounting configuration
Only roof mounting can guarantee a vertically polarized signal
A roof mounted antenna normally provides the most uniform radiation pattern
Roof mounted antennas are always the easiest to install

102. T9A14 -- Which of the following terms describes a type of loading when referring to an antenna?
Inserting an inductor in the radiating portion of the antenna to make it electrically longer
Inserting a resistor in the radiating portion of the antenna to make it resonant
Installing a spring at the base of the antenna to absorb the effects of collisions with other objects
Making the antenna heavier so it will resist wind effects when in motion

103. Practical Antenna Systems
Directional Antennas.
Directional antennas focus or direct RF energy in a desired direction.
Gain.
Apparent increase in power in the desired direction (both transmit and receive).

104. Practical Antenna Systems
Directional Antennas.
The most common type of directional antenna is the beam.
All beam antennas have parts called elements.
Metal rods.
Loops of wire.

105. Practical Antenna Systems
Directional Antennas.
Elements.
Driven element.
Connected to the radio by the feed line.
Reflector element.
Behind the driven element.
Director element(s).
In front of the driven element.
Can have more then one director.

106. Practical Antenna Systems
Directional Antennas.
The most common type of beam antenna is the Yagi-Uda array.
Normally just called a “Yagi”.
Invented in 1926 by Dr. Shintaro Uda in collaboration with Dr. Hidetsugu Yagi.
Rod-like elements.
Similar to TV antennas.

107. Practical Antenna Systems
Directional Antennas.
Yagi antennas.
Horizontally-polarized Yagi antennas are commonly used for long distance, weak signal CW & SSB communications on VHF & UHF.

108. Practical Antenna Systems
Directional Antennas.
Quad Antennas.
Square wire loop elements.

109. Practical Antenna Systems
Directional Antennas.
Parabolic Dish.
Large, round, curved reflector.
Very high gain.

110. Right-hand circular Left-hand circular Horizontal Vertical
T3A03 -- What antenna polarization is normally used for long-distance weak-signal CW and SSB contacts using the VHF and UHF bands?
Right-hand circular
Left-hand circular
Horizontal
Vertical

111. Change from vertical to horizontal polarization
T3A05 -- When using a directional antenna, how might your station be able to access a distant repeater if buildings or obstructions are blocking the direct line of sight path?
Change from vertical to horizontal polarization
Try to find a path that reflects signals to the repeater
Try the long path
Increase the antenna SWR

112. T9A01 -- What is a beam antenna?
An antenna built from aluminum I-beams
An omnidirectional antenna invented by Clarence Beam
An antenna that concentrates signals in one direction
An antenna that reverses the phase of received signals

113. T9A06 -- What type of antennas are the quad, Yagi, and dish?
Non-resonant antennas
Loop antennas
Directional antennas
Isotropic antennas

114. Practical Antenna Systems
Practical Feed Lines and Associated Equipment.
Feed line selection and maintenance.
Coax vs. Open Wire.
Coax easier to use.
VHF & UHF installations almost always use coaxial cable.
Open wire has lower loss.
Normally used only with HF wire antennas.

115. Practical Antenna Systems
Practical Feed Lines and Associated Equipment.
Feed line selection and maintenance.
Need to consider:
Frequency.
Length of cable.
Power level.
Budget.
Loss.
Larger cable generally has lower loss.
Foam dielectric has lower loss.

116. Practical Antenna Systems
Type
Impedance
30MHz
(dB/100ft)
150MHz
Cost
(per foot)
RG-174
50Ω
4.6 dB
10.3 dB
$0.20
RG-58
2.5 dB
5.6 dB
$0.28
RG-8X
2.0 dB
4.5 dB
$0.30
RG-8
1.1 dB
$1.00
RG-213
$0.89
LMR-400
0.7 dB
1.5 dB
$1.11
Type
Impedance
30MHz
(dB/100ft)
150MHz
Cost
(per foot)
RG-59
75Ω
1.8 dB
4.1 dB
$0.16
RG-6
1.4 dB
3.3 dB
$0.24
RG-11A
0.7 dB
1.6 dB
$0.97

117. Practical Antenna Systems
Practical Feed Lines and Associated Equipment.
Feed line selection and maintenance.
Coaxial cable must be protected.
Worst enemy is moisture getting into the cable.
Moisture increases loss in cable.
Avoid nicks or cuts in outer jacket.
Prolonged exposure to sunlight can result in tiny cracks in outer jacket which can admit moisture.
Seal outside connections against moisture.
Avoid sharp bends or turns.

118. Practical Antenna Systems
Practical Feed Lines and Associated Equipment.
Coaxial Feed Line Connections.
4 main types commonly used in amateur radio.
UHF.
Type “N”.
BNC.
SMA.

119. Practical Antenna Systems
Practical Feed Lines and Associated Equipment.
Coaxial Feed Line Connections.
UHF Connectors.
Most common type.
Up to 150 MHz.
High power (>1.5 kW).
Not constant impedance.
Not weather resistant.
Inexpensive.
Plug = PL-259.
Socket = SO-239.

120. Practical Antenna Systems
Practical Feed Lines and Associated Equipment.
Coaxial Feed Line Connections.
Type “N” Connectors.
Up to 10 GHz.
High power (>1.5 kW).
Constant impedance.
Both 50Ω and 75Ω versions.
Weather resistant.
Relatively expensive.
Relatively difficult to install.

121. Practical Antenna Systems
Practical Feed Lines and Associated Equipment.
Coaxial Feed Line Connections.
BNC Connectors.
Up to 4 GHz.
Low power.
Constant impedance.
Both 50Ω and 75Ω versions.
Commonly used on:
Older hand held radios.
Test equipment.

122. Practical Antenna Systems
Practical Feed Lines and Associated Equipment.
Coaxial Feed Line Connections.
SMA Connectors.
Up to 18 GHz.
Low power.
Constant impedance.
Only 50Ω available.
Used on most new hand held radios.

123. Moisture contamination Gamma rays The velocity factor exceeds 1.0
T7C09 -- Which of the following is the most common cause for failure of coaxial cables?
Moisture contamination
Gamma rays
The velocity factor exceeds 1.0
Overloading

124. Ultraviolet resistant jackets prevent harmonic radiation
T7C10 -- Why should the outer jacket of coaxial cable be resistant to ultraviolet light?
Ultraviolet resistant jackets prevent harmonic radiation
Ultraviolet light can increase losses in the cable’s jacket
Ultraviolet and RF signals can mix together, causing interference
Ultraviolet light can damage the jacket and allow water to enter the cable

125. It has more loss per foot It cannot be used for VHF or UHF antennas
T7C11 -- What is a disadvantage of air core coaxial cable when compared to foam or solid dielectric types?
It has more loss per foot
It cannot be used for VHF or UHF antennas
It requires special techniques to prevent water absorption
It cannot be used at below freezing temperatures

126. Practical Antenna Systems
Soldering.
A process in which two or more metal items are joined together by melting and flowing a filler metal into the joint.
The filler metal is called solder.
Flux is a material used to prevent the formation of oxides during the soldering process.

127. Practical Antenna Systems
Soldering.
Types of solder.
Standard solder.
Mixture of tin & lead.
Ratio of tin to lead is adjusted for lowest melting temperature.
63/37 or 60/40.
Melting point is about 183°C (361°F).
Lead-free solder.
Mixture of tin & silver.
Mixture of tin, silver, & copper.
Melting point is about 40°C (72°F) hotter than standard solder.

128. Practical Antenna Systems
Soldering.
Types of flux.
Resin.
Used for electrical/electronic connections.
Acid.
Used for plumbing.
NEVER use acid–core solder or acid flux to solder electronic connections!

129. Practical Antenna Systems
Soldering.
It takes a little bit of skill to make a good solder joint.
Good solder joint is bright & shiny.
If joint is not heated enough or if it is moved before it cools, it can result in a “cold solder joint”.
Cold solder joint is dull & grainy-looking.

130. Acid-core solder Silver solder Rosin-core solder Aluminum solder
T7D08 -- Which of the following types of solder is best for radio and electronic use?
Acid-core solder
Silver solder
Rosin-core solder
Aluminum solder

131. T7D09 -- What is the characteristic appearance of a cold solder joint?
Dark black spots
A bright or shiny surface
A grainy or dull surface
A greenish tint

132. Practical Antenna Systems
Practical Feed Lines and Associated Equipment.
SWR Meters and Wattmeters.
SWR Meter.
a.k.a. – SWR bridge.
Connects between transmitter & feed line.
Displays amount of mismatch (SWR) between transmitter & antenna system.
Antenna system = antenna + feed line.
Make adjustments to antenna system to minimize mismatch.

133. Practical Antenna Systems
Practical Feed Lines and Associated Equipment.
SWR Meters and Wattmeters.
SWR Meter.

134. Practical Antenna Systems
Simple SWR Meter.
Set to “FWD”.
Adjust “CAL” for full scale reading (SET).
Set to “REF” & read SWR.
Practical Feed Lines and Associated Equipment.
SWR Meters and Wattmeters.

135. Practical Antenna Systems
Practical Feed Lines and Associated Equipment.
SWR Meters and Wattmeters.
Cross-needle SWR meter.
No adjustments necessary.

136. Practical Antenna Systems
Directional Wattmeter.
Measures both forward power (PF) & reflected power (PR).
SWR can then be calculated from PF & PR.
Practical Feed Lines and Associated Equipment.
SWR Meters and Wattmeters.

137. Practical Antenna Systems
Practical Feed Lines and Associated Equipment.
Antenna Tuner.
One way to make antenna matching adjustments is to use an antenna tuner.
Antenna tuners are impedance transformers.
When used appropriately they are effective.
When used inappropriately all they do is make a bad antenna look good to the transmitter…the antenna is still bad.

138. Practical Antenna Systems
Practical Feed Lines and Associated Equipment.
Antenna Tuner.
a.k.a. -- Transmatch.
Does NOT “tune” the antenna.
Makes transmitter think all impedances are matched.

139. Practical Antenna Systems
Measures antenna impedance (Z).
Resistance (R).
Reactance (X).
Several other useful functions.
Practical Feed Lines and Associated Equipment.
Antenna analyzer.

140. Practical Antenna Systems
Practical Feed Lines and Associated Equipment.
Dummy Load.
A non-radiating load used for testing.
Non-inductive resistor & heatsink.
Typically 50Ω.

141. In series with the feed line, between the transmitter and antenna
T4A05 -- Where should an in-line SWR meter be connected to monitor the standing wave ratio of the station antenna system?
In series with the feed line, between the transmitter and antenna
In series with the station's ground
In parallel with the push-to-talk line and the antenna
In series with the power supply cable, as close as possible to the radio

142. T7C01 -- What is the primary purpose of a dummy load?
To prevent the radiation of signals when making tests
To prevent over-modulation of your transmitter
To improve the radiation from your antenna
To improve the signal to noise ratio of your receiver

143. A VTVM An antenna analyzer A Q meter A frequency counter
T7C02 -- Which of the following instruments can be used to determine if an antenna is resonant at the desired operating frequency?
A VTVM
An antenna analyzer
A Q meter
A frequency counter

144. Directional wattmeter
T7C08 -- What instrument other than an SWR meter could you use to determine if a feed line and antenna are properly matched?
Voltmeter
Ohmmeter
Iambic pentameter
Directional wattmeter

145. T7C13 -- What does a dummy load consist of?
A high-gain amplifier and a TR switch
A non-inductive resistor and a heat sink
A low voltage power supply and a DC relay
A 50 ohm reactance used to terminate a transmission line

146. Questions?

147. Chapter 5 Amateur Radio Equipment
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Chapter 5
Amateur Radio
Equipment