Z3D153 Volume 2 Ure
Questions and Answers
- 1.
Which US government agency divides the radio frequency spectrum into different bands?
- A.
Federal Aviation Agency.
- B.
American National Standard Institute.
- C.
Federal Communications Commission (FCC).
- D.
Institute of Electrical & Electronics Engineers, Inc.
Correct Answer
C. Federal Communications Commission (FCC).Explanation
The Federal Communications Commission (FCC) is the US government agency responsible for dividing the radio frequency spectrum into different bands. They regulate and allocate different frequencies to various users, such as television and radio broadcasters, wireless communication providers, and other industries that rely on wireless technology. The FCC ensures that these bands are used efficiently and that interference is minimized, enabling effective communication and the smooth operation of wireless devices and services.Rate this question:
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- 2.
High-frequency (HF) transmissions are normally conducted in which two operating modes?
- A.
Frequency modulation (FM) and independent sidebands (ISB).
- B.
Continuous wave (CW) and amplitude modulation (AM).
- C.
Single side band (SSB) and FM.
- D.
SSB and ISB.
Correct Answer
D. SSB and ISB.Explanation
High-frequency (HF) transmissions are normally conducted in two operating modes: Single sideband (SSB) and independent sidebands (ISB). SSB is a modulation technique that transmits only one sideband of the signal, resulting in more efficient use of bandwidth. ISB, on the other hand, transmits both sidebands independently, allowing for simultaneous transmission of multiple signals. These operating modes are commonly used in HF communications to maximize efficiency and improve signal quality.Rate this question:
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- 3.
Which frequency band is most susceptible to jamming?
- A.
Low frequency (LF)
- B.
Medium frequency (MF).
- C.
High frequency (HF).
- D.
Very high frequency (VHF).
Correct Answer
C. High frequency (HF).Explanation
High frequency (HF) is the correct answer because it is the range of frequencies that are most susceptible to jamming. This is because HF signals can travel long distances through the ionosphere, making them ideal for long-range communication. However, this also makes them more vulnerable to interference and jamming from natural phenomena like solar flares or man-made sources. Additionally, HF signals can be easily disrupted by atmospheric conditions, making them more susceptible to jamming compared to other frequency bands.Rate this question:
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- 4.
The ability of a receiver to reproduce the signal of a very weak station is characteristic of a receiver’s
- A.
Fidelity.
- B.
Capacity.
- C.
Sensitivity
- D.
Selectivity.
Correct Answer
C. SensitivityExplanation
The ability of a receiver to reproduce the signal of a very weak station is characteristic of a receiver's sensitivity. This means that a sensitive receiver is able to pick up and amplify weak signals, allowing the user to receive and listen to stations that may be far away or have low transmission power. Sensitivity is an important factor in determining the performance and effectiveness of a receiver in capturing and reproducing faint signals.Rate this question:
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- 5.
The ability of a receiver to reproduce the input signal accurately is characteristic of its
- A.
Fidelity
- B.
Capacity
- C.
Sensitivity.
- D.
Selectivity
Correct Answer
A. FidelityExplanation
Fidelity refers to the ability of a receiver to reproduce the input signal accurately. It measures how well the receiver can maintain the integrity of the original signal without any distortion or loss of information. A receiver with high fidelity will be able to faithfully reproduce the input signal, ensuring that the output is a true representation of the original signal. Therefore, fidelity is the characteristic that determines the accuracy of signal reproduction by a receiver.Rate this question:
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- 6.
A combination transmitter and receiver, built as a single unit and shares common tuned circuits, is called a
- A.
Transmitter.
- B.
Transceiver.
- C.
Receiver
- D.
Coupler.
Correct Answer
B. Transceiver.Explanation
A combination transmitter and receiver, built as a single unit and sharing common tuned circuits, is called a transceiver. This device is capable of both transmitting and receiving signals, making it a versatile and efficient solution for communication purposes. By integrating both functions into one unit, a transceiver simplifies the overall system design and reduces the need for separate components. It is commonly used in various applications such as telecommunications, radio systems, and wireless networks.Rate this question:
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- 7.
Conductor material resistance in a transmission line leads to this type of loss.
- A.
Copper.
- B.
Radiation
- C.
Inductive
- D.
Skin-effect
Correct Answer
A. Copper.Explanation
The given question asks for the type of loss that occurs due to the resistance of the conductor material in a transmission line. Copper is known to have a relatively low resistance compared to other conductor materials, such as aluminum. Therefore, when copper is used as the conductor material, the resistance and subsequent loss in the transmission line are minimized. Hence, the correct answer is copper.Rate this question:
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- 8.
The amount of skin-effect loss is directly proportional to the
- A.
Line length
- B.
Frequency
- C.
Voltage level
- D.
Resistive loss
Correct Answer
B. FrequencyExplanation
The amount of skin-effect loss is directly proportional to the frequency. Skin-effect is the tendency of alternating current to concentrate near the surface of a conductor, causing increased resistance and power loss. As the frequency increases, the skin depth decreases, resulting in a larger portion of the current flowing through the outer layers of the conductor. This increased concentration of current near the surface leads to higher resistance and more power loss, making the skin-effect loss directly proportional to the frequency.Rate this question:
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- 9.
Leakage loss in a transmission line is minimized by using a
- A.
Thinner conductor
- B.
thicker conductor
- C.
Very low-resistance dielectric
- D.
Very high-resistance dielectric.
Correct Answer
D. Very high-resistance dielectric.Explanation
Using a very high-resistance dielectric minimizes leakage loss in a transmission line because the high resistance of the dielectric material reduces the flow of current through it. This helps to prevent energy loss and maintain the efficiency of the transmission line. Thinner or thicker conductors do not directly affect leakage loss, and using a very low-resistance dielectric may actually increase leakage loss by allowing more current to flow through it.Rate this question:
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- 10.
A transmission line that consists of a center conductor, placed inside a rigid metal tube that functions as the outer shield, is called
- A.
Flexible coaxial cable.
- B.
Rigid coaxial cable.
- C.
Waveguide
- D.
Twin lead
Correct Answer
B. Rigid coaxial cable.Explanation
A transmission line that consists of a center conductor, placed inside a rigid metal tube that functions as the outer shield, is called a rigid coaxial cable. This type of cable provides excellent shielding and is commonly used in applications that require high-frequency signals and low signal loss. The rigid outer shield ensures that the electromagnetic waves are contained within the cable, preventing interference and signal degradation.Rate this question:
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- 11.
A waveguide is a type of transmission line that you would use
- A.
When the frequencies are so high that their wavelength is miniscule.
- B.
to transmit on frequencies too low for ground propagation.
- C.
for high power at frequencies up to 30 megahertz (MHz) primarily.
- D.
To receive television frequencies over the air.
Correct Answer
A. When the frequencies are so high that their wavelength is miniscule.Explanation
The correct answer is when the frequencies are so high that their wavelength is miniscule. This is because waveguides are designed to handle high-frequency signals and are most effective when the wavelength of the signal is small, such as in the microwave and millimeter wave frequency ranges. Waveguides provide a means of guiding and confining the electromagnetic waves within a structure, allowing for efficient transmission of high-frequency signals without significant loss or interference.Rate this question:
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- 12.
All statements concerning waveguides are true except
- A.
Their outer surface will arc from being very slightly damaged.
- B.
Their conductive material construction is easily dented.
- C.
Their effectiveness is hindered by moisture.
- D.
They can be destroyed by corrosion.
Correct Answer
A. Their outer surface will arc from being very slightly damaged.Explanation
The given answer states that "their outer surface will arc from being very slightly damaged" is not a true statement concerning waveguides. This means that waveguides do not experience arcing on their outer surface even if they are slightly damaged.Rate this question:
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- 13.
Which two transmission line properties determine its characteristic impedance (ZO)?
- A.
Inductance and resistance.
- B.
Inductance and capacitance
- C.
Resistance and capacitance.
- D.
Length and type of shielding.
Correct Answer
B. Inductance and capacitanceExplanation
The characteristic impedance of a transmission line is determined by two properties: inductance and capacitance. Inductance is the property that opposes changes in current flow, while capacitance is the property that opposes changes in voltage. These two properties interact to create the characteristic impedance, which is the ratio of voltage to current in a transmission line.Rate this question:
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- 14.
This is the correct statement concerning a wavelength.
- A.
Wavelength is inversely related to frequency.
- B.
Wavelength is directly related to frequency.
- C.
Wavelength is determined by the line length.
- D.
Wavelength is expressed in lambdas (λ).
Correct Answer
A. Wavelength is inversely related to frequency.Explanation
The correct answer is "Wavelength is inversely related to frequency." This means that as the frequency of a wave increases, the wavelength decreases, and vice versa. This relationship is a fundamental property of waves and is described by the equation: wavelength = speed of light / frequency. Therefore, when the frequency increases, the wavelength must decrease in order to maintain a constant speed of light.Rate this question:
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- 15.
Determine the wavelength of a 250 megahertz (MHz) signal.
- A.
12.0 meters
- B.
3.0 meters
- C.
1.5 meters
- D.
1.2 meters
Correct Answer
D. 1.2 metersExplanation
The wavelength of a signal can be determined by dividing the speed of light by the frequency of the signal. In this case, the frequency is given as 250 megahertz (MHz), which is equivalent to 250 million hertz (Hz). The speed of light is approximately 3 x 10^8 meters per second. By dividing the speed of light by the frequency, we can calculate the wavelength to be 1.2 meters.Rate this question:
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- 16.
A nonresonant transmission line is one with
- A.
Reflected waves
- B.
No reflected waves
- C.
Maximum voltage across its open termination.
- D.
Maximum voltage across its shorted termination.
Correct Answer
B. No reflected wavesExplanation
A nonresonant transmission line is designed to minimize reflections of waves. This means that there are no reflected waves in the transmission line. By eliminating reflected waves, the transmission line ensures efficient transmission of signals without any loss or distortion. Therefore, the correct answer is "no reflected waves."Rate this question:
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- 17.
When discussing resonant and nonresonant transmission lines,
- A.
Resonant lines are often referred to as flat lines
- B.
Maximum power transfer results from a resonant line
- C.
Maximum power transfer results from a nonresonant line
- D.
Significant loss and damage to equipment results from using a nonresonant line.
Correct Answer
C. Maximum power transfer results from a nonresonant line -
- 18.
This will likely result if a transmission line is terminated in an open.
- A.
Signal loss would be negligible.
- B.
Signal loss would be significant.
- C.
Current would be maximum at the termination.
- D.
Voltage would be minimum at the termination
Correct Answer
B. Signal loss would be significant.Explanation
If a transmission line is terminated in an open, it means that there is no load connected to the line. In this scenario, the signal would encounter a significant loss because there is no impedance matching between the source and the line. This mismatch causes a reflection of the signal, resulting in a loss of energy. Therefore, the correct answer is that signal loss would be significant.Rate this question:
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- 19.
Direct waves are radio waves that travel
- A.
Long distances with few interruptions.
- B.
From point to point along the Earth’s surface.
- C.
No more than 20 miles to the receive antenna
- D.
Through the air in a straight line from transmitter to receiver
Correct Answer
D. Through the air in a straight line from transmitter to receiverExplanation
Direct waves are radio waves that travel through the air in a straight line from the transmitter to the receiver. This means that there are no obstacles or interruptions in the path of the waves, allowing them to travel long distances without being obstructed. The statement "from point to point along the Earth's surface" is incorrect because it suggests that the waves travel along the surface, whereas direct waves travel through the air. The statement "no more than 20 miles to the receive antenna" is also incorrect because direct waves can travel much farther distances without significant loss of signal strength.Rate this question:
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- 20.
Radio waves that travel near the Earth’s surface are called
- A.
Earth waves
- B.
Global waves
- C.
Ground waves
- D.
Terrestrial waves
Correct Answer
C. Ground wavesExplanation
Ground waves are radio waves that travel near the Earth's surface. They are able to follow the curvature of the Earth and can travel for long distances. These waves are commonly used for broadcasting and communication purposes, as they can easily penetrate buildings and other obstacles. Therefore, ground waves are the correct term to describe radio waves that travel near the Earth's surface.Rate this question:
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- 21.
The Earth’s conductivity is determined by the type of
- A.
Atmospheric conditions at the time of transmission.
- B.
Air and moisture content in the propagation path.
- C.
Soil and water in the propagation path.
- D.
soil and air in the propagation path
Correct Answer
C. Soil and water in the propagation path.Explanation
The Earth's conductivity is determined by the type of soil and water in the propagation path. Soil and water have different conductive properties, which affect the transmission of electromagnetic signals through the Earth. The conductivity of the soil and water in the propagation path can vary depending on factors such as moisture content and composition. This conductivity plays a crucial role in determining the efficiency and effectiveness of signal transmission.Rate this question:
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- 22.
This term is used to describe radio waves that bend as they travel from one medium to another that has different density
- A.
Diffusion
- B.
Diffraction
- C.
Refraction
- D.
Reflection
Correct Answer
C. RefractionExplanation
Refraction is the correct answer because it is the term used to describe the bending of radio waves as they pass from one medium to another with different densities. This bending occurs due to the change in speed of the waves as they enter a new medium, causing them to change direction. Refraction is a common phenomenon that occurs with various types of waves, including radio waves, light waves, and sound waves.Rate this question:
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- 23.
The refractive index of air depends on moisture
- A.
Atmospheric pressure, and temperature.
- B.
atmospheric pressure, and frequency.
- C.
Receive signal level, and temperature
- D.
Receive signal level, and frequency.
Correct Answer
A. Atmospheric pressure, and temperature.Explanation
The refractive index of air is influenced by atmospheric pressure and temperature. Atmospheric pressure affects the density of air, which in turn affects the speed of light passing through it, leading to a change in the refractive index. Temperature also affects the density of air, causing variations in the refractive index. Moisture and frequency do not have a significant impact on the refractive index of air.Rate this question:
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- 24.
When comparing the radio and optical horizons, which one is farther away and by what percentage?
- A.
Optical; 15
- B.
Radio; 15.
- C.
Optical; 33.
- D.
Radio; 33
Correct Answer
B. Radio; 15.Explanation
The correct answer is "Radio; 15." This means that the radio horizon is farther away than the optical horizon by a percentage of 15. This suggests that the range of radio waves is greater than the range of optical waves, allowing radio signals to travel a longer distance before they become undetectable.Rate this question:
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- 25.
Which process permits communication in shadow regions behind obstacles?
- A.
Reflection
- B.
Scattering
- C.
Refraction
- D.
Diffraction
Correct Answer
D. DiffractionExplanation
Diffraction is the process that permits communication in shadow regions behind obstacles. Diffraction occurs when waves encounter an obstacle or pass through a narrow opening, causing them to spread out and bend around the edges of the obstacle. This bending of waves allows them to reach areas that would otherwise be in the shadow of the obstacle, enabling communication in those regions. Reflection, scattering, and refraction do not specifically involve the bending of waves around obstacles, making them incorrect options for this question.Rate this question:
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- 26.
Which frequency range will show little effect from precipitation?
- A.
HF
- B.
UHF
- C.
SHF
- D.
EHF
Correct Answer
A. HFExplanation
HF stands for High Frequency and refers to the frequency range between 3 to 30 MHz. This frequency range is less affected by precipitation because the radio waves in this range are able to penetrate through rain, snow, and other forms of precipitation with minimal attenuation. Therefore, HF signals can travel longer distances and are less likely to be disrupted by weather conditions compared to higher frequency bands like UHF, SHF, and EHF.Rate this question:
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- 27.
Line-of-sight (LOS) radio waves that are guided through the air between two layers of the atmosphere are known as
- A.
Channeling
- B.
Guiding
- C.
Ducting
- D.
Piping
Correct Answer
C. DuctingExplanation
Ducting refers to the phenomenon in which radio waves are guided through the air between two layers of the atmosphere. This allows for the transmission of signals over long distances, even beyond the normal line-of-sight range. Ducting is commonly observed in situations where there are temperature inversions in the atmosphere, causing the radio waves to follow a curved path due to differences in air density. This allows for communication over longer distances than what would be possible with line-of-sight transmission alone.Rate this question:
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- 28.
Which condition gives sky-wave propagation its ability to communicate beyond the optical line-of-sight (LOS)?
- A.
Refraction
- B.
Reflection
- C.
Earth’s conductivity
- D.
Atmospheric charge.
Correct Answer
A. RefractionExplanation
Refraction is the correct answer because it is the bending of radio waves as they pass through different layers of the atmosphere. This bending allows the waves to follow the curvature of the Earth and reach beyond the optical line-of-sight, enabling sky-wave propagation to communicate over long distances. Reflection, Earth's conductivity, and atmospheric charge do not directly contribute to the ability of sky-wave propagation to communicate beyond the optical line-of-sight.Rate this question:
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- 29.
The angle at which a radio wave enters the ionosphere is known as the
- A.
Skip angle
- B.
Critical angle
- C.
Angle of entrance
- D.
Angle of incidence
Correct Answer
D. Angle of incidenceExplanation
The angle at which a radio wave enters the ionosphere is known as the angle of incidence. This is the angle between the incident wave and the normal to the surface of the ionosphere. It determines how the wave will be refracted or reflected as it passes through the ionosphere. The angle of incidence is an important factor in understanding the behavior of radio waves in the ionosphere and is used in various calculations and models related to ionospheric propagation.Rate this question:
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- 30.
There are several critical sky-wave propagation angles and frequencies. Radio waves that angle too low are
- A.
Refracted
- B.
Returned to Earth
- C.
Absorbed before refraction occurs
- D.
Passed through the ionosphere into space
Correct Answer
C. Absorbed before refraction occursExplanation
Radio waves that angle too low are absorbed before refraction occurs. When radio waves are transmitted at a low angle towards the ionosphere, they encounter a denser part of the atmosphere. This denser region absorbs the radio waves, preventing them from being refracted back to Earth. As a result, the radio waves do not reach their intended destination and are effectively lost.Rate this question:
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- 31.
In sky-wave propagation, frequencies higher than the critical frequency are
- A.
Returned to Earth
- B.
Passed into space
- C.
The most desirable
- D.
Refracted by the F2 player
Correct Answer
B. Passed into spaceExplanation
In sky-wave propagation, frequencies higher than the critical frequency are passed into space. This means that these frequencies are able to penetrate the ionosphere and continue traveling through space instead of being reflected back to Earth. This is because the ionosphere, a layer of charged particles in the Earth's atmosphere, acts as a medium through which radio waves can propagate. However, when the frequency of the radio wave exceeds the critical frequency, it becomes too high to be refracted by the ionosphere and instead passes through it, allowing the wave to continue its journey into space.Rate this question:
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- 32.
The term frequency of optimum transmission (FOT) is also referred to as the
- A.
Outbound traffic frequency
- B.
Optimum tropospheric frequency
- C.
Optimum traffic frequency.
- D.
Frequency of outbound transmission.
Correct Answer
C. Optimum traffic frequency.Explanation
The term frequency of optimum transmission (FOT) refers to the frequency at which transmission of data or signals is most efficient and effective. It is commonly known as the optimum traffic frequency because it represents the frequency that allows for the smoothest and most optimal flow of traffic or communication. This frequency ensures that the transmission is not hindered by interference or other factors, resulting in the best possible performance.Rate this question:
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- 33.
In sky- and ground-wave propagation, the area of silence where no signals are received is known as the
- A.
Propagation distance
- B.
Skip distance
- C.
Dead zone
- D.
Skip zone
Correct Answer
D. Skip zoneExplanation
The skip zone refers to the area where no signals are received in sky- and ground-wave propagation. This occurs due to the phenomenon of signal skipping, where the signal is refracted or reflected away from the receiver. As a result, there is a region where the signal does not reach the receiver, leading to a silence or dead zone. Therefore, the correct answer is skip zone.Rate this question:
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- 34.
This occurs when a transmitted signal travels over two or more separate paths during transmission
- A.
Skip effects
- B.
Modulation
- C.
Multipathing
- D.
Magneton splitting
Correct Answer
C. MultipathingExplanation
Multipathing refers to the phenomenon where a transmitted signal takes multiple paths during transmission. This can occur when the signal reflects off objects or encounters obstacles in its path. As a result, multiple versions of the signal reach the receiver at slightly different times, causing interference and signal degradation. This can lead to issues such as signal fading, ghosting, or poor reception in wireless communication systems.Rate this question:
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- 35.
How many layers make up the Earth’s atmosphere?
- A.
2
- B.
3
- C.
4
- D.
5
Correct Answer
D. 5Explanation
The Earth's atmosphere is composed of five layers: the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. Each layer has its own unique characteristics and plays a crucial role in the Earth's climate and weather patterns.Rate this question:
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- 36.
This occurs when high-energy ultraviolet light waves from the sun enter the ionospheric region of the atmosphere and strike the gas atoms.
- A.
Ionization
- B.
Modulation
- C.
Conductivity
- D.
Recombination
Correct Answer
A. IonizationExplanation
When high-energy ultraviolet light waves from the sun enter the ionospheric region of the atmosphere and strike the gas atoms, ionization occurs. This means that the UV light causes the gas atoms to lose or gain electrons, resulting in the formation of ions. This process increases the number of ions in the ionospheric region, affecting the electrical conductivity of the atmosphere. Therefore, ionization is the correct answer as it explains the phenomenon of high-energy UV light causing ion formation in the atmosphere.Rate this question:
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- 37.
The atmospheric recombination process is dependent on the
- A.
Season
- B.
Time of day (TOD)
- C.
Regular variation
- D.
Irregular variations
Correct Answer
B. Time of day (TOD)Explanation
The atmospheric recombination process refers to the process in which ions and free electrons in the atmosphere recombine to form neutral molecules. This process is dependent on the time of day (TOD) because the concentration of ions and free electrons in the atmosphere varies throughout the day. During the day, the ionization rate is higher due to the presence of sunlight, which leads to more ions and free electrons in the atmosphere. As the day progresses and sunlight decreases, the ionization rate decreases, resulting in a decrease in the concentration of ions and free electrons. Therefore, the time of day plays a crucial role in the atmospheric recombination process.Rate this question:
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- 38.
Which layer of the ionosphere is most important for high-frequency (HF) communications?
- A.
D
- B.
E
- C.
F
- D.
Topside
Correct Answer
C. FExplanation
The F layer is the most important layer of the ionosphere for high-frequency (HF) communications. It is located at an altitude of about 150 to 400 km above the Earth's surface. The F layer is responsible for reflecting HF radio waves back to the Earth, allowing long-distance communication over large areas. It is also known for its ability to refract radio waves, allowing them to travel beyond the horizon. The F layer is further divided into two sub-layers, F1 and F2, with the F2 layer being the most significant for HF communications.Rate this question:
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- 39.
During which season do we have the wider range of critical frequencies and less absorption of all frequencies?
- A.
Fall
- B.
Winter
- C.
Spring
- D.
Summer
Correct Answer
B. WinterExplanation
In winter, the air is colder and denser, which affects the propagation of sound waves. The colder air allows for a wider range of critical frequencies, meaning that a broader range of frequencies can be heard more clearly. Additionally, the colder air has less absorption of all frequencies, allowing sound waves to travel further without being absorbed or attenuated. Therefore, winter is the season when we have a wider range of critical frequencies and less absorption of all frequencies.Rate this question:
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- 40.
As ionospheric solar variations, sunspots are disturbances that appear and disappear
- A.
In the sun’s atmosphere
- B.
On the sun’s surface.
- C.
In the ionosphere.
- D.
Beneath the sun’s surface.
Correct Answer
B. On the sun’s surface.Explanation
Sunspots are disturbances that appear and disappear on the sun's surface. These dark spots are cooler regions caused by intense magnetic activity. They are associated with the sun's magnetic field and are often seen in groups or pairs. Sunspots are important because they can affect space weather and have an impact on Earth's ionosphere.Rate this question:
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- 41.
On which regular ionospheric variation do sunspots occur?
- A.
11-day cycle
- B.
11-week cycle
- C.
11-month cycle
- D.
11-year cycle.
Correct Answer
D. 11-year cycle.Explanation
Sunspots occur on an 11-year cycle. Sunspots are dark areas on the surface of the sun that are cooler than their surroundings. These spots are caused by intense magnetic activity on the sun, which follows an 11-year cycle known as the solar cycle. During this cycle, the number of sunspots increases and decreases, reaching a maximum and minimum every 11 years. This variation in sunspots has an impact on the ionosphere, which is the upper part of the Earth's atmosphere, causing regular ionospheric variations.Rate this question:
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- 42.
In a basic communication system, this is used to convert radio frequency (RF) current oscillation into electric and magnetic fields of force.
- A.
Antenna
- B.
Transmitter
- C.
Coupler
- D.
Transmission lines
Correct Answer
A. AntennaExplanation
The correct answer is antenna. In a basic communication system, an antenna is used to convert radio frequency current oscillation into electric and magnetic fields of force. The antenna radiates these fields into space, allowing for the transmission and reception of electromagnetic waves.Rate this question:
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- 43.
The concept where alternating current (AC) changes in magnitude, and reverses its direction during each cycle, is
- A.
An unproven hypothesis.
- B.
The definition of propagation
- C.
What makes radio transmission possible.
- D.
What led to the discovery of direct current (DC).
Correct Answer
C. What makes radio transmission possible.Explanation
The concept where alternating current (AC) changes in magnitude, and reverses its direction during each cycle, is what makes radio transmission possible. Radio transmission relies on the ability of AC to oscillate and change direction, allowing the transmission of information through electromagnetic waves. This concept is fundamental to the functioning of radio technology and is the basis for the transmission and reception of radio signals.Rate this question:
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- 44.
At which point do magnetic fields around a wire no longer have time to collapse completely between alternations?
- A.
60 cycles per second (cps).
- B.
120 cps.
- C.
10,000 cps.
- D.
15,000 cps
Correct Answer
C. 10,000 cps.Explanation
At 10,000 cps, the alternations of the current in the wire occur at a very high frequency. This high frequency means that the time between each alternation is very short. As a result, the magnetic fields around the wire do not have enough time to collapse completely before the next alternation occurs. This is why at 10,000 cps, the magnetic fields no longer have time to collapse completely between alternations.Rate this question:
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- 45.
In radio-wave creation, which type of field detaches from the antenna and travels through space at great distances?
- A.
Radiation
- B.
Induction
- C.
Gravitational
- D.
Electromotive
Correct Answer
A. RadiationExplanation
Radio-wave creation involves the generation of electromagnetic waves, which detach from the antenna and travel through space at great distances. This process is known as radiation. Electromagnetic radiation is characterized by the oscillation of electric and magnetic fields perpendicular to each other and to the direction of propagation. These waves carry energy and information, allowing for the transmission of radio signals over long distances.Rate this question:
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- 46.
Which types of polarization do most satellite communication terminals transmit and receive?
- A.
Transmit horizontal and receive vertical polarizations
- B.
Transmit vertical and receive horizontal polarizations.
- C.
Transmit right-hand circular and receive left-hand circular polarizations.
- D.
Transmit left-hand circular and receive right-hand circular polarizations
Correct Answer
C. Transmit right-hand circular and receive left-hand circular polarizations.Explanation
Most satellite communication terminals transmit and receive right-hand circular polarizations. This type of polarization is commonly used in satellite communication because it provides better resistance to signal fading caused by atmospheric conditions and other interference. By transmitting right-hand circular polarization and receiving left-hand circular polarization, the terminals can achieve better signal quality and reliability.Rate this question:
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- 47.
A resonant antenna effectively radiates a radio signal for frequencies close to its designed frequency. Which percentage range, plus or minus, is it usually within?
- A.
1
- B.
2
- C.
3
- D.
4
Correct Answer
B. 2Explanation
A resonant antenna is designed to operate at a specific frequency, and it is most efficient in radiating a radio signal at that frequency. However, due to various factors such as manufacturing tolerances and environmental conditions, the antenna may also radiate effectively for frequencies slightly higher or lower than its designed frequency. This range is typically within a percentage range of plus or minus 2% of the designed frequency.Rate this question:
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- 48.
The design frequency of a resonant antenna is 10 megahertz (MHz). What will be its frequency range?
- A.
8–10 MHz.
- B.
9–11 MHz
- C.
9.5–10.5 MHz
- D.
9.8–10.2 MHz.
Correct Answer
D. 9.8–10.2 MHz.Explanation
The design frequency of a resonant antenna represents the frequency at which the antenna is designed to operate optimally. However, due to various factors such as manufacturing tolerances and environmental conditions, the actual frequency range in which the antenna will perform effectively may vary slightly from the design frequency. In this case, the correct answer suggests that the frequency range for the resonant antenna is expected to be between 9.8 and 10.2 MHz, indicating a slight deviation from the design frequency of 10 MHz.Rate this question:
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- 49.
The lowest frequency at which an antenna resonates is known as its
- A.
Standing wave
- B.
Fundamental
- C.
Resonation
- D.
Primary
Correct Answer
B. FundamentalExplanation
The lowest frequency at which an antenna resonates is known as its fundamental frequency. This frequency represents the basic or primary resonance of the antenna, and it is the frequency at which the antenna vibrates most efficiently. The other options, such as standing wave, resonation, and primary, do not accurately describe the lowest frequency of resonance for an antenna.Rate this question:
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- 50.
The ability of an antenna to both receive and transmit equally well is known as the antenna’s
- A.
Bandwidth
- B.
Resonance
- C.
Reciprocity
- D.
Effectiveness
Correct Answer
C. ReciprocityExplanation
Reciprocity refers to the ability of an antenna to both receive and transmit signals equally well. This means that the antenna's characteristics remain the same regardless of whether it is used for receiving or transmitting. In other words, if an antenna is efficient in receiving signals, it will also be efficient in transmitting signals, and vice versa. This property is important in various communication systems where the same antenna is used for both sending and receiving signals.Rate this question:
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