Login or Register for FREE!
Login or Register for FREE!
Subel. ZLH
50 questions
Subelement ZLH
From Transmitter to Receiver
Section ZLH28
Propagation
A 'skip zone' is
  • the distance between the antenna and where the refracted wave first returns to earth
  • Correct Answer
    the distance between the far end of the ground wave and where the refracted wave first returns to earth
  • the distance between any two refracted waves
  • a zone caused by lost sky waves
This question does not yet have an explanation! Register to add one

Tags: none

The medium which reflects high frequency radio waves back to the earth's surface is called the
  • biosphere
  • stratosphere
  • Correct Answer
    ionosphere
  • troposphere
This question does not yet have an explanation! Register to add one

Tags: none

The highest frequency that will be reflected back to the earth at any given time is known as the
  • UHF
  • Correct Answer
    MUF
  • OWF
  • LUF
This question does not yet have an explanation! Register to add one

Tags: none

All communications frequencies throughout the spectrum are affected in varying degrees by the
  • atmospheric conditions
  • ionosphere
  • aurora borealis
  • Correct Answer
    sun
This question does not yet have an explanation! Register to add one

Tags: none

Solar cycles have an average length of
  • 1 year
  • 3 years
  • 6 years
  • Correct Answer
    11 years
This question does not yet have an explanation! Register to add one

Tags: none

The 'skywave' is another name for the
  • Correct Answer
    ionospheric wave
  • tropospheric wave
  • ground wave
  • inverted wave
This question does not yet have an explanation! Register to add one

Tags: none

The polarisation of an electromagnetic wave is defined by the direction of
  • the H field
  • propagation
  • Correct Answer
    the E field
  • the receiving antenna
This question does not yet have an explanation! Register to add one

Tags: none

That portion of HF radiation which is directly affected by the surface of the earth is called
  • ionospheric wave
  • local field wave
  • Correct Answer
    ground wave
  • inverted wave
This question does not yet have an explanation! Register to add one

Tags: none

Radio wave energy on frequencies below 4 MHz during daylight hours is almost completely absorbed by this ionospheric layer
  • C
  • Correct Answer
    D
  • E
  • F
This question does not yet have an explanation! Register to add one

Tags: none

Because of high absorption levels at frequencies below 4 MHz during daylight hours, only high angle signals are normally reflected back by this layer
  • C
  • D
  • Correct Answer
    E
  • F
This question does not yet have an explanation! Register to add one

Tags: none

Scattered patches of high ionisation developed seasonally at the height of one of the layers is called
  • Correct Answer
    sporadic-E
  • patchy
  • random reflectors
  • trans-equatorial ionisation
This question does not yet have an explanation! Register to add one

Tags: none

For long distance propagation, the radiation angle of energy from the antenna should be
  • Correct Answer
    less than 30 degrees
  • more than 30 degrees but less than forty-five
  • more than 45 degrees but less than ninety
  • 90 degrees
This question does not yet have an explanation! Register to add one

Tags: none

The path radio waves normally follow from a transmitting antenna to a receiving antenna at VHF and higher frequencies is a
  • circular path going north or south from the transmitter
  • great circle path
  • Correct Answer
    straight line
  • bent path via the ionosphere
This question does not yet have an explanation! Register to add one

Tags: none

A radio wave may follow two or more different paths during propagation and produce slowly-changing phase differences between signals at the receiver resulting in a phenomenon called
  • absorption
  • baffling
  • Correct Answer
    fading
  • skip
This question does not yet have an explanation! Register to add one

Tags: none

The distance from the far end of the ground wave to the nearest point where the sky wave returns to the earth is called the
  • skip distance
  • radiation distance
  • skip angle
  • Correct Answer
    skip zone
This question does not yet have an explanation! Register to add one

Tags: none

High Frequency long-distance propagation is most dependent on
  • Correct Answer
    ionospheric reflection
  • tropospheric reflection
  • ground reflection
  • inverted reflection
This question does not yet have an explanation! Register to add one

Tags: none

The layer of the ionosphere mainly responsible for long distance communication is
  • C
  • D
  • E
  • Correct Answer
    F
This question does not yet have an explanation! Register to add one

Tags: none

The ionisation level of the ionosphere reaches its minimum
  • just after sunset
  • Correct Answer
    just before sunrise
  • at noon
  • at midnight
This question does not yet have an explanation! Register to add one

Tags: none

One of the ionospheric layers splits into two parts during the day called
  • A & B
  • D1 & D2
  • E1 & E2
  • Correct Answer
    F1 & F2
This question does not yet have an explanation! Register to add one

Tags: none

Signal fadeouts resulting from an 'ionospheric storm' or 'sudden ionospheric disturbance' are usually attributed to
  • heating of the ionised layers
  • over-use of the signal path
  • insufficient transmitted power
  • Correct Answer
    solar flare activity
This question does not yet have an explanation! Register to add one

Tags: none

The 80 metre band is useful for working
  • in the summer at midday during high sunspot activity
  • long distance during daylight hours when absorption is not significant
  • all points on the earth's surface
  • Correct Answer
    up to several thousand kilometres in darkness but atmospheric and man-made noises tend to be high
This question does not yet have an explanation! Register to add one

Tags: none

The skip distance of radio signals is determined by the
  • type of transmitting antenna used
  • power fed to the final amplifier of the transmitter
  • only the angle of radiation from the antenna
  • Correct Answer
    both the height of the ionosphere and the angle of radiation from the antenna
This question does not yet have an explanation! Register to add one

Tags: none

Three recognised layers of the ionosphere that affect radio propagation are
  • A, E, F
  • B, D, E
  • C, E, F
  • Correct Answer
    D, E, F
This question does not yet have an explanation! Register to add one

Tags: none

Propagation on 80 metres during the summer daylight hours is limited to relatively short distances because of
  • Correct Answer
    high absorption in the D layer
  • the disappearance of the E layer
  • poor refraction by the F layer
  • pollution in the T layer

The D layer is the bottom layer of the ionosphere during the daylight. It absorbs medium and high frequency waves, 10 MHz and below.

Last edited by dogshed. Register to edit

Tags: none

The distance from the transmitter to the nearest point where the sky wave returns to the earth is called the
  • angle of radiation
  • maximum usable frequency
  • Correct Answer
    skip distance
  • skip zone
This question does not yet have an explanation! Register to add one

Tags: none

A variation in received signal strength caused by slowly changing differences in path lengths is called
  • absorption
  • Correct Answer
    fading
  • fluctuation
  • path loss
This question does not yet have an explanation! Register to add one

Tags: none

VHF and UHF bands are frequently used for satellite communication because
  • Correct Answer
    waves at these frequencies travel to and from the satellite relatively unaffected by the ionosphere
  • the Doppler frequency change caused by satellite motion is much less than at HF
  • satellites move too fast for HF waves to follow
  • the Doppler effect would cause HF waves to be shifted into the VHF and UHF bands.
This question does not yet have an explanation! Register to add one

Tags: none

The 'critical frequency' is defined as the
  • highest frequency to which your transmitter can be tuned
  • lowest frequency which is reflected back to earth at vertical incidence
  • minimum usable frequency
  • Correct Answer
    highest frequency which will be reflected back to earth at vertical incidence
This question does not yet have an explanation! Register to add one

Tags: none

The speed of a radio wave
  • varies indirectly to the frequency
  • Correct Answer
    is the same as the speed of light
  • is infinite in space
  • is always less than half the speed of light
This question does not yet have an explanation! Register to add one

Tags: none

The MUF for a given radio path is the
  • mean of the maximum and minimum usable frequencies
  • Correct Answer
    maximum usable frequency
  • minimum usable frequency
  • mandatory usable frequency
This question does not yet have an explanation! Register to add one

Tags: none

The position of the E layer in the ionosphere is
  • above the F layer
  • Correct Answer
    below the F layer
  • below the D layer
  • sporadic
This question does not yet have an explanation! Register to add one

Tags: none

A distant amplitude-modulated station is heard quite loudly but the modulation is at times severely distorted. A similar local station is not affected. The probable cause of this is
  • transmitter malfunction
  • Correct Answer
    selective fading
  • a sudden ionospheric disturbance
  • front end overload
This question does not yet have an explanation! Register to add one

Tags: none

Skip distance is a term associated with signals through the ionosphere. Skip effects are due to
  • Correct Answer
    reflection and refraction from the ionosphere
  • selective fading of local signals
  • high gain antennas being used
  • local cloud cover
This question does not yet have an explanation! Register to add one

Tags: none

The type of atmospheric layers which will best return signals to earth are
  • oxidised layers
  • heavy cloud layers
  • Correct Answer
    ionised layers
  • sun spot layers
This question does not yet have an explanation! Register to add one

Tags: none

The ionosphere
  • is a magnetised belt around the earth
  • consists of magnetised particles around the earth
  • Correct Answer
    is formed from layers of ionised gases around the earth
  • is a spherical belt of solar radiation around the earth
This question does not yet have an explanation! Register to add one

Tags: none

The skip distance of a sky wave will be greatest when the
  • ionosphere is most densely ionised
  • signal given out is strongest
  • Correct Answer
    angle of radiation is smallest
  • polarisation is vertical
This question does not yet have an explanation! Register to add one

Tags: none

If the height of the reflecting layer of the ionosphere increases, the skip distance of a high frequency transmission
  • stays the same
  • decreases
  • varies regularly
  • Correct Answer
    becomes greater
This question does not yet have an explanation! Register to add one

Tags: none

If the frequency of a transmitted signal is so high that we no longer receive a reflection from the ionosphere, the signal frequency is above the
  • speed of light
  • sun spot frequency
  • skip distance
  • Correct Answer
    maximum usable frequency
This question does not yet have an explanation! Register to add one

Tags: none

A 'line of sight' transmission between two stations uses mainly the
  • ionosphere
  • troposphere
  • sky wave
  • Correct Answer
    ground wave
This question does not yet have an explanation! Register to add one

Tags: none

The distance travelled by ground waves in air
  • is the same for all frequencies
  • Correct Answer
    is less at higher frequencies
  • is more at higher frequencies
  • depends on the maximum usable frequency
This question does not yet have an explanation! Register to add one

Tags: none

The radio wave from the transmitter to the ionosphere and back to earth is correctly known as the
  • Correct Answer
    sky wave
  • skip wave
  • surface wave
  • F layer
This question does not yet have an explanation! Register to add one

Tags: none

Reception of high frequency radio waves beyond 4000 km normally occurs by the
  • ground wave
  • skip wave
  • surface wave
  • Correct Answer
    sky wave
This question does not yet have an explanation! Register to add one

Tags: none

A 28 MHz radio signal is more likely to be heard over great distances
  • if the transmitter power is reduced
  • Correct Answer
    during daylight hours
  • only during the night
  • at full moon
This question does not yet have an explanation! Register to add one

Tags: none

The number of high frequency bands open to long distance communication at any time depends on
  • Correct Answer
    the highest frequency at which ionospheric reflection can occur
  • the number of frequencies the receiver can tune
  • the power being radiated by the transmitting station
  • the height of the transmitting antenna
This question does not yet have an explanation! Register to add one

Tags: none

Regular changes in the ionosphere occur approximately every 11
  • days
  • months
  • Correct Answer
    years
  • centuries
This question does not yet have an explanation! Register to add one

Tags: none

When a HF transmitted radio signal reaches a receiver, small changes in the ionosphere can cause
  • consistently stronger signals
  • a change in the ground wave signal
  • Correct Answer
    variations in signal strength
  • consistently weaker signals
This question does not yet have an explanation! Register to add one

Tags: none

The usual effect of ionospheric storms is to
  • increase the maximum usable frequency
  • Correct Answer
    cause a fade-out of sky-wave signals
  • produce extreme weather changes
  • prevent communications by ground wave
This question does not yet have an explanation! Register to add one

Tags: none

Changes in received signal strength when sky wave propagation is used are called
  • ground wave losses
  • modulation losses
  • Correct Answer
    fading
  • sunspots
This question does not yet have an explanation! Register to add one

Tags: none

Although high frequency signals may be received from a distant station by a sky wave at a certain time, it may not be possible to hear them an hour later. This may be due to
  • Correct Answer
    changes in the ionosphere
  • shading of the earth by clouds
  • changes in atmospheric temperature
  • absorption of the ground wave signal
This question does not yet have an explanation! Register to add one

Tags: none

VHF or UHF signals transmitted towards a tall building are often received at a more distant point in another direction because
  • these waves are easily bent by the ionosphere
  • Correct Answer
    these waves are easily reflected by objects in their path
  • you can never tell in which direction a wave is travelling
  • tall buildings have elevators
This question does not yet have an explanation! Register to add one

Tags: none

Go to ZLH27 Go to ZLJ30
HamStudy.org™ is copyright 2024 Signal Stuff™, All rights reserved.
View Privacy Policy    |    Get help with HamStudy.org™