DX6ARC - Amateur Radio Club of Capiz

[Information] : Where a question shows [Information]. All the information given below that question is Ok

Ionosphere [Information]
1. The ionosphere is defined as the layer of the Earth's atmosphere that is ionized by solar and cosmic radiation. It lies 75-1000 km (46-621 miles) above the Earth.
2. The ionosphere reflects and modifies radio waves used for communication and navigation. The ionosphere grows and shrinks depending on the energy it absorbs from the Sun.
3. Within the ionosphere there are several different ionospheric regions which affect the propagation of radio signals in different ways - the D layer, E layer, F layer which splits into F1 and F2 layers all affect radio signals differently.
4. When using HF propagation via the ionosphere, the radio signals leave the transmitting radio antenna on Earth's surface and travel towards the ionosphere where some of these are returned to Earth.
Sporadic-E skip is caused by large patches of ionization in the ______ of the ionosphere.
1. D-layer of the ionosphere.
2. E-layer of the ionosphere.
3. F-layer of the ionosphere.
4. F1-layer of the ionosphere.
The earth’s daily ionospheric charge varies approximately in proportion of what ?
1. the broadband
2. the weather
3. the moon cycle
4. the sunspot cycle
Satellites that is placed at the equatorial orbit of the earth are called ?
1. geostationary satelillites
2. stationery satelillites
3. fixed orbit satelillites
4. man made satelillites
Tropospheric scatter is used with frequencies in the following range ____
1. LF
2. UHF
3. VHF
4. HF
Skip condition is caused by : [Information]
1. In radio communication, skywave or skip refers to the propagation of radio waves reflected or refracted back toward Earth from the ionosphere, an electrically charged layer of the upper atmosphere.
2. Skip is a name used to describe atmospheric conditions that allow for radio transmissions to travel long distances.
3. A skip distance is a distance on the Earth's surface between the two points (transmitter and receiver) where radio waves from a transmitter, refracted downwards by different layers of the ionosphere fall.
Refraction and Super Refraction : [Information]
1. Refraction: The change in direction (bending) of a wave....An electromagnetic wave is refracted when it passes a medium of different density.
2. Refraction : Radio waves are refracted by different layers in the Earth's atmosphere. This leads to a reduction in the signal, making it difficult for them to be received over long distances. Unlike radio waves, microwaves are not refracted, so they are used for satellite communications.
3. Super Refraction : An abnormally rapid decrease in the refractive index with height in the atmosphere, leading to anomalous propagation of radio waves, generally marked by an increase in their range.
Ground conductivity : [Information]
1. Ground conductivity refers to the electrical conductivity of the subsurface of the earth. In the International System of Units (SI) it is measured in millisiemens per meter (mS/m).
2. With dry soil and decreasing moisture content giving a poor connection whereas damp and increasing moist soil giving a better connection. Salty sea water is best.
3. Ground conductivity can be improved by artificial means. An example would be the radial ground system of a vertical antenna.
The layer of the ionosphere which is the most important reflecting medium for high frequency radio waves is the ____
1. F1 layer
2. F2 layer
3. F3 layer
4. F4 layer
The lowest layer in the ionosphere existing at an average height of 70 kms , with an average thickness of 10 kms is ____
1. D-layer
2. Atmospheric layer
3. B-layer
4. Lowest layer
High frequency waves are affected by _____
1. earth's orbit
2. weather cycle
3. solar cycle
4. moon cycle
Standard broadcast station on medium frequency uses this type of propagation for most of its signals _____
1. air
2. medium
3. sky
4. ground
Troposcatter propagation is subject two forms of fading. One is fast occurring several times per minute at its worst. This is known as ______
1. Reyleight fading
2. Tropo fading
3. Sporadic fading
4. Intermittent
The three types of radio waves are skywaves, space waves and ______ waves
1. air
2. ground
3. electrical
4. hand
The absorption of radio waves by the atmosphere depends on _____
1. the distance
2. the antenna
3. the frequency
4. the wind speed
The highest frequency for a given layer in the ionosphere that will be returned down to earth by that layer after having been beamed straightly (vertically) is called the _____ frequency
1. sky-wave
2. power
3. maximum
4. critical
When a signal is returned to earth by the ionosphere, what is this called?
1. ground-wave propagation
2. tropospheric propagation
3. atmospheric propagation
4. sky-wave propagation
Critical Frequency : [Information]
1. Q : What is the highest frequency that can be sent straight upward and be returned to earth?
  A : critical frequency
2. The radio wave will be returned to earth at all frequencies below the critical frequency.
3. The frequency at which a signal sent vertically will pass right through the ionosphere is called the critical frequency
4. Critical Frequency changes with time of day, atmospheric conditions and angle of fire of the radio waves by antenna.
That part of the total radiation that is directed towards the ionosphere is called ?
1. sky waves
2. electrical waves
3. conductance waves
4. radiated waves
The shortest distance from a transmitter measured along the surface of earth at which a sky wave of fixed frequency will be returned to earth is known as ?
1. medium distance
2. long distance
3. high distance
4. skip distance
Transverse nature of Electromagnetic waves : [Information]
1. In electromagnetic waves, polarization is due to the transverse nature of the waves
2. In an electromagnetic wave, electric and magnetic field vectors are perpendicular to each other and at the same time are perpendicular to the direction of propagation of the wave. This nature of electromagnetic wave is known as Transverse nature.
The ground waves eventually disappear as one moves away from the transmitter because of _____
1. absorption
2. tilting
3. bending
4. distance
What takes place when electromagnetic waves pass from sharp edges of obstacles or small slits ?
1. restriction
2. direction
3. reflection
4. diffraction
What is the most affected frequency band by changes in solar cycle?
1. HF
2. MF
3. VHF
4. UHF
Another means of propagating UHF signals is by use of beyond the horizon propagation known as_______
1. distance scatter
2. propagation scatter
3. troposcatter
4. space scatter
The frequency band most useable for groundwave propagation ?
1. 300 - 3000MHz
2. 30 - 300 MHz
3. 300 - 3000MHz
4. 300 - 3000KHz
The lowest radio frequency used in radio communication is _____
1. 20 khz
2. 10 khz
3. 40 khz
4. 30 khz
The 4 primary layers of the atmosphere on Earth: [Information]
1. Troposphere : The lowest part of the Earth's atmosphere is called the troposphere and it extends from the surface up to about 20 kms thick.
2. Stratosphere : The atmosphere from about 20 km to 50 km is the stratosphere.
3. The Mesosphere : From 50kms to 85 Kms above earth. The friction within this layer causes meteors to burn up.
4. The Thermosphere : The thickest layer in the atmosphere is the thermosphere starting at about 85km to 700km above the earth.
  Contains D, E and F layers.
For a given layer of the atmosphere, the highest frequency that will be returned to the earth by that layer, having been beamed straight up to it "?
1. refracted frequency
2. reflected frequency
3. skip frequency
4. hop frequency
The ground waves eventually disappear as one moves away from the transmitter because of ______
1. power transmitted
2. antenna height
3. maximum hop distance limit
4. mountains
Very low frequency (VLF) waves are used in some types of services because _____
1. they are very reliable
2. they are useful
3. less interference
4. less power needed
The bending of radio waves as they pass over a terrain feature such as hill or mountain ?
1. polarisation
2. diversion
3. diffraction
4. bendification
When microwave signals follow the curvature of the earth this is known as _____
1. bending
2. clouding
3. curving
4. ducting
One of these may cause ionic disturbance characterized by rapid fluttering sound hence voice communications are poor ?
1. wind speed
2. sunspot activity
3. climate changes
4. typhoons
The most ionized layer in the ionosphere ?
1. F1 layer
2. F2 layer
3. F3 layer
4. F4 layer
In propagating space wave, the most practical frequency band to use is ____
1. VHF
2. UHF
3. GHF
4. MHF
Selective Fading :
1. Selective fading or frequency selective fading is a radio propagation anomaly caused by partial cancellation of a radio signal by itself — the signal arrives at the receiver by two different paths, and at least one of the paths is changing (lengthening or shortening).
Tropospheric scatter
1. This method of propagation uses the tropospheric scatter phenomenon, where radio waves at UHF and SHF frequencies are randomly scattered as they pass through the upper layers of the troposphere.
Which of the following describes selective fading?
1. Variability of signal strength with beam heading
2. Partial cancellation of some frequencies within the received pass band
3. Sideband inversion within the ionosphere
4. Degradation of signal strength due to backscatter
Aurora propagation [Information]
1. The cause of Aurora activity is the interaction of charged particles from the Sun with the Earth’s magnetic field and the ionosphere.... Aurora activity occurs in the E-region of the ionosphere... Aurora only appears around the polar regions
2. SSB signals are raspy
3. Signals propagating through the Aurora are fluttery
4. CW signals appear to be modulated by white noise
What is transequatorial propagation (TEP)? [Information]
1. Transequatorial propagation is a mode of propagation that is sometimes experienced when transmitting across the equator and it can provide communication when not expected.
2. Propagation between two mid-latitude points at approximately the same distance north and south of the magnetic equator
Line of Sight (LOS) [Information]
1. is a type of propagation that can transmit and receive data only where transmit and receive stations are in view of each other without any sort of an obstacle between them. FM radio, microwave and satellite transmission are examples of line-of-sight communication.
2. Line-of-sight propagation is a characteristic of electromagnetic radiation or acoustic wave propagation which means waves travel in a direct path from the source to the receiver. Electromagnetic transmission includes light emissions traveling in a straight line.
Ground conductivity refers to
1. the resistance of the antenna earth to ground
2. the conductivity of a copper earth strap to the earth
3. the voltage between the antenna and the ground
4. the electrical conductivity of the subsurface of the earth.
Maximum Usable Frequency (MUF), Lowest Useable Frequency (LUF) and Frequency of Optimum Transmission (FOT): [Information]
1. MUF : It is that highest frequency of radio waves which when sent at some angle towards ionosphere, gets reflected and returns to the surface of the earth.
  It is the highest radio frequency that can be used for transmission between two points via reflection from the ionosphere.
2. MUF : When a signal is transmitted using HF propagation, over a given path there is a maximum frequency that can be used.
3. LUF : Lowest Usable Frequency (LUF) is defined as the frequency at below which the signal falls below the minimum strength required for satisfactory reception
4. FOT : Frequency of optimum transmission (FOT), in the transmission of radio waves via ionospheric reflection, is the highest effective (i.e. working) frequency that is predicted to be usable for a specified path and time for 90% of the days of the month. ... optimum working frequency........The most effective frequency at a specified time for ionospheric propagation of radio waves between two specified points.
Sudden Ionospheric Disturbance (SID) [Information]
1. Sudden ionosphric disturbance (SID) are often experienced on the HF or short wave bands where they may also be called blackouts…They can last from a few minutes to several hours…Only effects the sunlit side of earth
2. A sudden ionospheric disturbance usually occurs in association with a solar flare and is seen only on the sunlit side of the earth….UV-rays and X-rays from a solar flare travel to earth at the speed of light (186,000 mi/sec) and greatly increase ionization level of the D-region with the lower frequencies more greatly effected
3. Sudden Ionospheric Disturbance (SID) is an abnormally high ionization/plasma density in the D region of the ionosphere caused by a solar flare. The SID results in a sudden increase in radio-wave absorption that is most severe in the upper medium frequency (MF) and lower high frequency (HF) ranges, and as a result often interrupts or interferes with telecommunications systems the recovery can take minutes or hours....
Sporadic E or Es is a propagation mode via the ionosphere which can allow _________ to propagate over long distances via a reflection from the E layer.
1. VHF signals (30 - 300 MHz)
2. HF signals (3 - 30 MHz)
3. UHF signals (300 MHz - 3 GHz)
4. MF signals (300 kHz - 3 MHz)
Absorption fading: [Information]
1. Absorption fading is due to various amounts of absorption which take place in the ionosphere and troposphere and the period of fading is longer than for interference or polarization fading. A SID (Sudden Ionospheric Disturbance) is a extreme case of absorption fading.
2. As the frequency rises, absorption effects become more important.
Which part of the atmosphere enables the propagation of radio signals
around the world?
1. stratosphere
2. troposphere
3. ionosphere
4. biosphere
Which of the following is a likely cause of irregular fading of signals received
by ionospheric refection?
1. low power transmitted
2. random combining of signals arriving via different paths
3. poor receiving antenna
4. receiver problem
The distance travelled by ground waves
1. is less at higher frequencies
2. depends on the maximum usable frequency
3. is the same for all frequencies
4. is more at higher frequencies
How does the range of sky-wave propagation compare to ground- wave propagation?
1. It is much longer
2. It is much shorter
3. It depends on the weather
4. It is about the same
The radio wave which follows a path from the transmitter to the ionosphere and back to earth is known correctly as the
1. sky wave
2. surface wave
3. ionospheric wave
4. ground wave
Radio Waves.....Reflection : Refraction and Diffraction [Information]
1. Reflection involves a change in direction of waves when they bounce off a barrier (Ionosphere)........Radio waves below 40 MHz are significantly affected by the ionosphere, primarily because radio waves in this frequency range are effectively reflected by the ionosphere.
2. Refraction occurs when a wave crosses a boundary from one medium to another...... A wave entering a medium at an angle will change direction........The amount of refraction that occurs depends on three main factors: (1) the density of ionization of the layer, (2) the frequency of the radio wave, and (3) the angle at which the wave enters the layer.
3. Diffraction refers to the "bending of waves around an edge" of an object. Diffraction depends on the size of the object relative to the wavelength of the wave
To what distance is VHF propagation ordinarily limited ?
1. Approximately 300 miles
2. Approximately 400 miles
3. Approximately 500 miles
4. Approximately 600 miles
A ship to ship communication plagued by fading, the best solution seems to be the use of ________
1. frequency diversity
2. increase transmitter power
3. change frequency
4. earth rod
Electromagnetic waves are refracted when they pass into a ______
1. vortex
2. medium of different die electric constant
3. void
4. black hole
The angle above which the sky wave will no longer return to earth when propagated over the ionosphere is called
1. frequency angle
2. sky angle
3. right angle
4. critical angle
Waveguide is a transmission channel between the transmitter and the antenna.
1. wireless signals
2. microwave signals
3. electronic signals
4. air wave signals
VHF is generally radiated through _________
1. ground waves
2. sky waves
3. space waves
4. air waves
Match the following frequencies with their corresponding propagation MW, HF, VHF.
1. MW - groundwave
  HF - spacewaves
  VHF – skywaves
2. MW - skywave
  HF - groundwave
  VHF – spacewaves
3. MW - spacewaves
  HF - skywaves
  VHF - groundwave
4. MW - groundwave
  HF - skywaves
  VHF - spacewaves
Distances near the skip distance should be used for sky wave propagation to _____
1. so as to exceed the critical frequency
2. to avoid tilting
3. to avoid the Faraday effect
4. to prevent sky-wave and upper ray interference
Scatter Propagation : Ionospheric Scatter [Information]
1. Scatter Propagation : Transmission of radio waves far beyond line-of-sight distances by using high power and a large transmitting antenna to beam the signal upward into the atmosphere and by using a similar large receiving antenna to pick up the small portion of the signal that is scattered by the atmosphere. Also known as beyond-the-horizon communication; forward-scatter propagation; over-the-horizon propagation.
2. Ionospheric Scatter : A form of scatter propagation in which radio waves are scattered by the lower E layer of the ionosphere to permit communication over distances from 600 to 1400 miles (1000 to 2250 kilometers) when using the frequency range of about 25 to 100 megahertz.
Ionospheric Layers: D, E, F, F1 and F2 : [Information]
1. D Region : It is present at altitudes between about 60 and 90 kilometres and the radiation within it is only present during the day to an extent that affects radio waves noticeably.
2. The E region or E layer is above the D region. It exists at altitudes between about 100 and 125 kilometres. Instead of attenuating radio communications signals this layer chiefly refracts them, often to a degree where they are returned to earth.
3. F Region : The combined F layer may then be centred around 250 to 300 kilometres and is the most important region in the ionosphere for long distance HF radio communications.During the daytime when radiation is being received from the Sun, it often splits into two: F1 and F2
4. F1 and F2 Regions : The lower one being the F1 region and the higher one, the F2 region. Of these the F1 region generally only exists in the summer.Typically the F1 layer is found at around an altitude of 300 kilometres with the F2 layer above it at around 400 kilometres.
Approximate height of geostationary satellite from the earth's surface ?
1. 36,000 km
2. 40,000 km
3. 46,000 km
4. 50,000 km
Meteor Burst Communications (MBC):[Information]
1. Meteor scatter or meteor burst communications uses a form of radio propagation that utilises the dense trails of ionisation left by meteors as they enter the upper layers of the Earth's atmosphere to establish brief communications paths between radio stations up to 2,250 kilometres (1,400 miles) apart.The trails are dense and can reflect signals into the VHF and sometimes the UHF region of the radio spectrum, but they are only present for a very short time, and therefore the radio system must be able to accommodate this.
What kind of radio wave is the same day or night ?
1. space wave
2. sky wave
3. ground wave
4. medium wave
Skip Zone : [Information]
1. The skip zone, which may also be called a silent zone or dead zone, is a region where a radio transmission can not be received. The skip zone is the region between the point where the ground wave signals can no longer be heard and the point where the skywave first returns to Earth.
2. Skip zone width depends on depends on the height and shape of the ionosphere
If the ground reflected waves and direct waves arrive at a point at different phase angles, the signal suffers an increase and decrease of level known as:
1. signal attenuation
2. fading
3. distortion
4. weak signal
Sunspot Cycle : [Information]
1. The amount of magnetic flux that rises up to the Sun's surface varies with time in a cycle called the solar cycle. This cycle lasts 11 years on average. This cycle is sometimes referred to as the sunspot cycle.
2. The greatest number of sunspots in any given solar cycle is designated as the “solar maximum" and the lowest number is referred to as the “solar minimum” phase.
3. Higher sunspot numbers generally indicate a greater probability of good propagation at higher frequencies. HF propagation is done through bouncing Electro-Magnetic waves off of charged particles in the earth's atmosphere.
Ground Wave : [Information]
1. Ground Wave propagation is a method of radio wave propagation that uses the area between the surface of the earth and the ionosphere for transmission. The ground wave can propagate a considerable distance over the earth's surface particularly in the low frequency and medium frequency portion of the radio spectrum.
2. A radio wave that reaches a receiver from a transmitter directly, without reflection from the ionosphere.
Radio Path Horizon [Information]
1. While we say that VHF/UHF communications is “line of sight,” the distance that a VHF/UHF radio wave will travel is slightly longer than the line-of-sight distance....We call this distance the “radio horizon” or “radio-path horizon
2. The VHF/UHF radio-path horizon distance exceeds the geometric horizon by approximately 15% of the distance
3. The radio-path horizon distance exceeds the geometric horizon because of downward bending due to density variations in the atmosphere
Tropospheric propagation : [Information]
1. Tropospheric propagation describes electromagnetic propagation in relation to the troposphere. The service area from a VHF or UHF radio transmitter extends to just beyond the optical horizon, at which point signals start to rapidly reduce in strength.
2. Tropospheric propagation occurs when signals are reflected scattered or refracted in the troposphere.
3. Tropospheric propagation effects occur comparatively close to the surface of the Earth. The radio signals are affected by the region that is below an altitude of about 2 kilometres. As these regions are those that are greatly affected by the weather, there is a strong link between weather conditions and radio propagation conditions and coverage.
4. At times conditions change and radio signals may be detected over distances of 500 or even 1000 km and more. This is normally by a form of tropospheric enhancement, often called "tropo" for short.
Ducting : Atmospheric ducting and Tropospheric ducting : [Information]
1. Atmospheric ducting : Is a mode of propagation of electromagnetic radiation, usually in the lower layers of Earth's atmosphere, where the waves are bent by atmospheric refraction. ... It also causes long distance propagation of radio signals in bands that would normally be limited to line of sight.
2. Tropospheric ducting : At times conditions change and radio signals may be detected over distances of 500 or even 1000 km and more. This is normally by a form of tropospheric enhancement, often called "tropo" for short. At times signals may even be trapped in an elevated duct in a form of radio signal propagation known as tropospheric ducting.
3. Tropospheric refraction : Radio waves can propagate over the horizon when the lower atmosphere of the earth bends, scatters, and/or reflects the electromagnetic fields. These effects are collectively known as tropospheric propagation, or tropo for short. ... This effect is known as tropospheric scatter, or troposcatter.
4. Tropospheric ducting : Is an atmospheric effect caused by a differential temperature layer that causes reflection or refraction of radio wave. These reflective layers can form a radio wave "duct"
EME Propagation : [Information]
1. Earth–Moon–Earth communication, also known as moon bounce, is a radio communications technique that relies on the propagation of radio waves from an Earth-based transmitter directed via reflection from the surface of the Moon back to an Earth-based receiver.
Regular Daily Variations : [Information]
1. Daily : variations in the ionosphere are a result of the 24-hour rotation of the Earth about its axis.
2. Seasonal : variations are the result of the Earth revolving around the sun; the relative position of the sun moves from one hemisphere to the other with changes in seasons. Seasonal variations of the D, E, and F1 layers correspond to the highest angle of the sun; thus the ionization density of these layers is greatest during the summer.
3. Eleven Year Sunspot Cycle :The solar cycle or solar magnetic activity cycle is the nearly periodic 11-year change in the Sun's activity and appearance. The changes on the Sun cause effects in space, in the atmosphere, and on Earth's surface.
  This cycle has both a minimum and maximum level of sunspot activity that occur approximately every 11 years.
4. The number of sunspots in existence at any one time is continually subject to change as some disappear and new ones emerge.
Auroral propagation : [Information]
1. The phenomenon of the electromagnetic energy being returned to the earth as a result of unusual solar activity causing aurora. The aurora occur in the ionosphere, in the E-region
2. Auroral propagation is characterized by rapid flutter, which makes voice signals such as AM (amplitude modulation), FM (frequency modulation), or SSB (single sideband) unreadable most of the time. This propagation method is highly unreliable.
3. SSB signals are raspy.
4. Morse code (cw) mode is best for Aurora propagation.
Chordal hop propagation : [Information]
1. Chordal hop propagation occurs when a radio wave is refracted by the ionosphere such that the refracted wave hits the ionosphere again before hitting the ground. The primary characteristic of chordal hop propagation is successive ionospheric reflections without an intermediate reflection from the ground
2. Chordal hop propagation is desirable because the signal experiences less loss along the path compared to normal skip propagation
Radio propagation : [Information]
1. Radio propagation is the way radio waves travel or propagate when they are transmitted from one point to another and affected by the medium in which they travel and in particular the way they propagate around the Earth in various parts of the atmosphere.
2. Propagation is the process by which radio waves get from the antenna of the transmitter to the antenna of a distant receiver.
Amateur Satellites [Information]
1. There are a number of amateur satellites in orbit that will relay signals in various modes, including FM, SSB, CW and digital modes. They act like terrestrial repeaters, except that signals are usually sent up to the satellite on one band (the uplink band) and received from it on a different band (the downlink band).
2. Amateur satellites were traditionally given an Oscar number by Amsat, the international Amateur Satellite Corporation. OSCAR meant “Orbital Satellite Carrying Amateur Radio”
Backscatter [Information]
1. Backscatter: This term is usually used to mean the RF waves are reflected approximately 180 degrees, back in the direction from which they came.
  
  When ionospheric propagation takes place, some of the signal after the first hop is scattered back in its direction of origin. The signal then reflects from the ionosphere, landing up in the general area where it originated.
2. The modulation of the station heard via backscatter, has a specific 'sound‘. It sounds hollow like talking through a large tube and sometimes even a short echo is heard.
3. Backscatter is a typical F2-layer propagationmode but is also observed with E-layer propagation.....Most of the time backscatter signals are not very strong.
4. Backscatter allows communication within the skip zone. Normally, station within skip zone cannot hear transmitting station
Absorption [Information]
1. Absorption : D layer when ionized during daylight absorbs RF energy, the longer the wave the more the absorption, resulting in no sky wave on 80 and 160 meters during daylight hrs
  
  Geomagnetic disturbances and solar flares increase absorption…noise level increase as signals decrease….More pronounced for paths over the polar regions.
VHF/UHF Propagation [Information]
1. Normally communication is line of sight.
  
  Tropospheric Propagation – refraction of waves increases radio horizon to 1.15 times visual line-of-sight.
  
  Sporadic E Reflection – reflection of waves off highly ionised sections of the E Layer
2. Auroral Reflection / Scattering – reflection of waves off ionised regions at higher latitudes (Northern Lights)
3. Earth-Moon-Earth (EME) – reflection off the moon. Maximum power, large antennas and the best receivers are needed to overcome free space and reflection losses and cosmic noise
4. Meteor Scatter – reflection from the ionised trails left by meteors. Brief contacts lasting from a few seconds to a minute or more
Signal Attenuation [Information]
1. Radio waves weaken as they travel
2. Energy is lost due to absorption when waves propagate through the atmosphere or solid medium – effect of atmosphere negligible from 10MHz – 3GHz
3. Energy is also lost during reflection, diffraction and refraction
4. The ability to resolve a particular signal is determined by the signal-to-noise ratio at the receiver input
Fading [Information]
1. Fluctuations of the received signal are called fading.
2. Signals arriving at the receiver by more than one path (multipath – due to ionospheric variations) can either reinforce or cancel one another
3. Polarisation of the radio wave may be changed by propagation conditions resulting in an apparent reduction of strength
4. At vhf and uhf fading may be attributed to varying atmospheric conditions, temperature, humidity, etc.
The ionosphere causes radio signals to be....
1. absorbed
2. diffused
3. reflected
4. refracted
It is the lower limit of the range of frequencies that provide useful communication between two given points by the way of the ionosphere.
1. LUF
2. MUF
3. CUF
4. SUF
What is the highest layer of the atmosphere?
1. ozone layer
2. troposphere
3. ionosphere
4. stratosphere
In tropospheric scatter propagation, the attenuation is dependent on ......
1. take-off angle
2. antenna size
3. scatter angle
4. weather
If the transmitter power remains constant, an increase in the frequency of the sky wave will ..
1. reduce the length of the skip distance
2. increase the range of the ground wave
3. have no effect on the ground wave range
4. lengthen the skip distance
The signal refracted back from the ionosphere strikes the earth and is reflected back up to the ionosphere again to be bent and sent back to earth.
1. skip transmission
2. hop transmission
3. multi-hop transmission
4. multi transmission
Tropospheric scatter is used with frequencies in the following range
1. HF
2. VHF
3. UHF
4. VLF
What is the primary cause of ionization in the atmosphere?
1. sun spots
2. cosmic rays
3. blaster rays
4. Ultraviolet radiation
The ability of the ionosphere to reflect a radio wave back to the earth is determined by
1. Operatiing frequency
2. Ion density
3. Angle of incidence
4. All of the above
Ducting occurs in which region of the atmosphere?
1. Ionosphere
2. Ozone layer
3. Troposphere
4. Stratosphere
What is transequatorial propagation ?
1. Propagation between two points at approximately the same distance north and south of the magnetic equator
2. Propagation between two points on the magnetic equator
3. Propagation between two continent by way of ducts along the magnetic equator
4. Propagation between any two station at the same latitude
The D layer of the ionosphere absorbs _________ waves.
1. VHF and UHF
2. HF and VHF
3. LF and MF
4. MF and HF
A space wave is...
1. Skywave
2. Radio wave
3. Surface wave
4. Line of sight propagation wave
Refraction is caused by what factors?
1. Changes in troposphere’s density and temperature
2. Water content
3. Relative conductivity
4. All of the above
The type of atmospheric layers which will best return signals to earth are:
1. oxidised layers
2. sun spot layers
3. ionised layers
4. heavy cloud layers
The layer of the ionosphere mainly responsible for long distance communication is:
1. C
2. D
3. E
4. F
Propagation - Attenuation [Information]
1. Radio waves weaken as they travel
2. Energy is lost due to absorption when waves propagate through the atmosphere or solid medium – effect of atmosphere negligible from 10MHz – 3GHz
3. Energy is also lost during reflection, diffraction and refraction
4. The ability to resolve a particular signal is determined by the signal-to-noise ratio at the receiver input
Solar Flux (solar noise measured at UHF)
1. is used a indicator to the ionosphere activity
2. is used a guide to the sunspot activity
3. is used as an indicator of solar activity
4. is used a guide to the sun's activity
This reviewer - 4F3EW - 9 November 2021

DU6MOT • Aklan, Philippines

NTC Class A Element 10 (X)