Technician Class License Exam Questions

Subelement T3

Radio wave characteristics: properties of radio waves; propagation modes

Groups

T3A - Radio wave characteristics: how a radio signal travels; fading; multipath; wavelength vs. penetration; antenna orientation
T3B - Radio and electromagnetic wave properties: the electromagnetic spectrum; wavelength vs. frequency; velocity of electromagnetic waves; calculating wavelength
T3C - Propagation modes: line of sight; sporadic E; meteor and auroral scatter and reflections; tropospheric ducting; F layer skip; radio horizon

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Group T3A Radio wave characteristics: how a radio signal travels; fading; multipath; wavelength vs. penetration; antenna orientation

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

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

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

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

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

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

T3A07 What type of wave carries radio signals between transmitting and receiving stations?

Electromagnetic
Electrostatic
Surface acoustic
Magnetostrictive

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

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

T3A10 What may occur if data signals propagate over multiple paths?

Transmission rates can be increased by a factor equal to the number of separate paths observed
Transmission rates must be decreased by a factor equal to the number of separate paths observed
No significant changes will occur if the signals are transmitting using FM
Error rates are likely to increase

T3A11 Which part of the atmosphere enables the propagation of radio signals around the world?

The stratosphere
The troposphere
The ionosphere
The magnetosphere

Group T3B Radio and electromagnetic wave properties: the electromagnetic spectrum; wavelength vs. frequency; velocity of electromagnetic waves; calculating wavelength

T3B01 What is the name for the distance a radio wave travels during one complete cycle?

Wave speed
Waveform
Wavelength
Wave spread

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

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

T3B04 How fast does a radio wave travel through free space?

At the speed of light
At the speed of sound
Its speed is inversely proportional to its wavelength
Its speed increases as the frequency increases

T3B05 How does the wavelength of a radio wave relate to its frequency?

The wavelength gets longer as the frequency increases
The wavelength gets shorter as the frequency increases
There is no relationship between wavelength and frequency
The wavelength depends on the bandwidth of the signal

T3B06 What is the formula for converting frequency to approximate wavelength in meters?

Wavelength in meters equals frequency in hertz multiplied by 300
Wavelength in meters equals frequency in hertz divided by 300
Wavelength in meters equals frequency in megahertz divided by 300
Wavelength in meters equals 300 divided by frequency in megahertz

T3B07 What property of radio waves is often used to identify the different frequency bands?

The approximate wavelength
The magnetic intensity of waves
The time it takes for waves to travel one mile
The voltage standing wave ratio of waves

T3B08 What are the frequency limits of the VHF spectrum?

30 to 300 kHz
30 to 300 MHz
300 to 3000 kHz
300 to 3000 MHz

T3B09 What are the frequency limits of the UHF spectrum?

30 to 300 kHz
30 to 300 MHz
300 to 3000 kHz
300 to 3000 MHz

T3B10 What frequency range is referred to as HF?

300 to 3000 MHz
30 to 300 MHz
3 to 30 MHz
300 to 3000 kHz

T3B11 What is the approximate velocity of a radio wave as it travels through free space?

3000 kilometers per second
300,000,000 meters per second
300,000 miles per hour
186,000 miles per hour

Group T3C Propagation modes: line of sight; sporadic E; meteor and auroral scatter and reflections; tropospheric ducting; F layer skip; radio horizon

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

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

T3C03 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

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

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

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

T3C07 What band is best suited for communicating via meteor scatter?

10 meters
6 meters
2 meters
70 cm

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

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

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

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

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