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SUBELEMENT T3 – Radio wave characteristics: properties of radio waves; propagation modes – [3 Exam Questions - 3 Groups]

 

T3A - Radio wave characteristics: how a radio signal travels; fading; multipath; polarization; wavelength vs absorption; antenna orientation 

 

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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?

A. Change the batteries in your radio to a different type

B. Turn on the CTCSS tone

C. Ask the other operator to adjust his squelch control

D. Try moving a few feet or changing the direction of your antenna if possible, as reflections may be causing multi-path distortion

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T3A02

Why might the range of VHF and UHF signals be greater in the winter? 

A. Less ionospheric absorption

B. Less absorption by vegetation

C. Less solar activity

D. Less tropospheric absorption 

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T3A03

What antenna polarization is normally used for long-distance weak-signal CW and SSB contacts using the VHF and UHF bands?

A. Right-hand circular

B. Left-hand circular

C. Horizontal

D. Vertical

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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?

A. The modulation sidebands might become inverted

B. Signals could be significantly weaker

C. Signals have an echo effect on voices

D. Nothing significant will happen

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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?

A. Change from vertical to horizontal polarization

B. Try to find a path that reflects signals to the repeater

C. Try the long path

D. Increase the antenna SWR

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T3A06

What term is commonly used to describe the rapid fluttering sound sometimes heard from mobile stations that are moving while transmitting?

A. Flip-flopping

B. Picket fencing

C. Frequency shifting

D. Pulsing

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T3A07 

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

A. Electromagnetic

B. Electrostatic

C. Surface acoustic

D. Magnetostrictive

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T3A08

Which of the following is a likely cause of irregular fading of signals received by ionospheric reflection?

A. Frequency shift due to Faraday rotation

B. Interference from thunderstorms

C. Random combining of signals arriving via different paths 

D. Intermodulation distortion 

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T3A09

Which of the following results from the fact that skip signals refracted from the ionosphere are elliptically polarized?

A. Digital modes are unusable

B. Either vertically or horizontally polarized antennas may be used for transmission or reception

C. FM voice is unusable

D. Both the transmitting and receiving antennas must be of the same polarization

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T3A10

What may occur if data signals propagate over multiple paths?

A. Transmission rates can be increased by a factor equal to the number of separate paths observed

B. Transmission rates must be decreased by a factor equal to the number of separate paths observed

C. No significant changes will occur if the signals are transmitting using FM

D. Error rates are likely to increase

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T3A11

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

A. The stratosphere

B. The troposphere

C. The ionosphere

D. The magnetosphere

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T3A12

How might fog and light rain affect radio range on 10 meters and 6 meters? 

A. Fog and rain absorb these wavelength bands

B. Fog and light rain will have little effect on these bands

C. Fog and rain will deflect these signals 

D. For and rain will increase radio range 

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T3A13

What weather condition would decrease range at microwave frequencies? 

A. High winds

B. Low barometric pressure

C. Precipitation

D. Colder temperatures 

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T3B - Radio and electromagnetic wave properties: the electromagnetic spectrum; wavelength vs frequency; nature and velocity of electromagnetic waves; definition of UHF, VHF, HF bands; calculating wavelength 

 

 

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T3B01

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

A. Wave speed

B. Waveform

C. Wavelength

D. Wave spread

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T3B02

What property of a radio wave is used to describe its polarization?

A. The orientation of the electric field

B. The orientation of the magnetic field

C. The ratio of the energy in the magnetic field to the energy in the electric field

D. The ratio of the velocity to the wavelength

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T3B03

What are the two components of a radio wave?

A. AC and DC

B. Voltage and current

C. Electric and magnetic fields

D. Ionizing and non-ionizing radiation

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T3B04

How fast does a radio wave travel through free space?

A. At the speed of light

B. At the speed of sound

C. Its speed is inversely proportional to its wavelength

D. Its speed increases as the frequency increases

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T3B05

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

A. The wavelength gets longer as the frequency increases

B. The wavelength gets shorter as the frequency increases

C. There is no relationship between wavelength and frequency

D. The wavelength depends on the bandwidth of the signal

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T3B06

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

A. Wavelength in meters equals frequency in hertz multiplied by 300

B. Wavelength in meters equals frequency in hertz divided by 300

C. Wavelength in meters equals frequency in megahertz divided by 300

D. Wavelength in meters equals 300 divided by frequency in megahertz

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T3B07

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

A. The approximate wavelength

B. The magnetic intensity of waves

C. The time it takes for waves to travel one mile

D. The voltage standing wave ratio of waves

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T3B08

What are the frequency limits of the VHF spectrum?

A. 30 to 300 kHz

B. 30 to 300 MHz

C. 300 to 3000 kHz

D. 300 to 3000 MHz

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T3B09

What are the frequency limits of the UHF spectrum?

A. 30 to 300 kHz

B. 30 to 300 MHz

C. 300 to 3000 kHz

D. 300 to 3000 MHz

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T3B10

What frequency range is referred to as HF?

A. 300 to 3000 MHz

B. 30 to 300 MHz

C. 3 to 30 MHz

D. 300 to 3000 kHz

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T3B11

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

A. 3000 kilometers per second

B. 300,000,000 meters per second

C. 300,000 miles per hour

D. 186,000 miles per hour

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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?

A. They are too weak to go very far

B. FCC regulations prohibit them from going more than 50 miles

C. UHF signals are usually not reflected by the ionosphere

D. They collide with trees and shrubbery and fade out

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T3C02

Which of the following is an advantage of HF vs VHF and higher frequencies? 

A. HF antennas are generally smaller 

B. HF accommodates wider bandwidth signals 

C. Long distance ionospheric propagation is far more common on HF 

D. There is less atmospheric interference (static) on HF 

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T3C03

What is a characteristic of VHF signals received via auroral reflection?

A. Signals from distances of 10,000 or more miles are common

B. The signals exhibit rapid fluctuations of strength and often sound distorted

C. These types of signals occur only during winter nighttime hours

D. These types of signals are generally strongest when your antenna is aimed west

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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?

A. Backscatter

B. Sporadic E

C. D layer absorption

D. Gray-line propagation

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T3C05

Which of the following effects might cause radio signals to be heard despite obstructions between the transmitting and receiving stations?

A. Knife-edge diffraction

B. Faraday rotation

C. Quantum tunneling 

D. Doppler shift

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T3C06

What mode is responsible for allowing over-the-horizon VHF and UHF communications to ranges of approximately 300 miles on a regular basis?

A. Tropospheric scatter

B. D layer refraction

C. F2 layer refraction

D. Faraday rotation

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T3C07

What band is best suited for communicating via meteor scatter?

A. 10 meters

B. 6 meters

C. 2 meters

D. 70 cm

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T3C08

What causes tropospheric ducting?

A. Discharges of lightning during electrical storms

B. Sunspots and solar flares

C. Updrafts from hurricanes and tornadoes

D. Temperature inversions in the atmosphere

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T3C09

What is generally the best time for long-distance 10 meter band propagation via the F layer?

A. From dawn to shortly after sunset during periods of high sunspot activity

B. From shortly after sunset to dawn during periods of high sunspot activity

C. From dawn to shortly after sunset during periods of low sunspot activity

D. From shortly after sunset to dawn during periods of low sunspot activity

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T3C10

Which of the following bands may provide long distance communications during the peak of the sunspot cycle? 

A. Six or ten meters 

B. 23 centimeters 

C. 70 centimeters or 1.25 meters 

D. All of these choices are correct

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T3C11

Why do VHF and UHF radio signals usually travel somewhat farther than the visual line of sight distance between two stations?

A. Radio signals move somewhat faster than the speed of light

B. Radio waves are not blocked by dust particles

C. The Earth seems less curved to radio waves than to light

D. Radio waves are blocked by dust particles

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