Z3D153 Volume 2 Ure (2019)
All answers as of 3/25/2019 have been checked by a bunch of radio nerds, and are correct.
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 correct answer because it is the US government agency responsible for regulating and dividing the radio frequency spectrum into different bands. The FCC is tasked with managing and allocating the limited radio spectrum resources to ensure efficient and interference-free communication for various industries and services, including broadcasting, telecommunications, and wireless technologies.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 Single Sideband (SSB) and Independent Sidebands (ISB) operating modes. SSB is a modulation technique that suppresses the carrier and one of the sidebands, allowing for efficient use of bandwidth. ISB, on the other hand, is a technique where multiple sidebands are transmitted independently, enabling simultaneous transmission of multiple signals. Both SSB and ISB are commonly used in HF transmissions due to their efficiency and ability to transmit multiple signals.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 frequency band that is most susceptible to jamming. This is because HF signals can travel long distances and can be easily disrupted by natural phenomena like solar flares or atmospheric disturbances. Additionally, HF signals can be easily intercepted and disrupted by intentional jamming devices, making this frequency band particularly vulnerable to interference.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
Sensitivity refers to a receiver's ability to detect and reproduce weak signals. A receiver with high sensitivity can pick up and amplify even very faint signals, allowing it to reproduce the signal of a weak station accurately. Fidelity refers to the accuracy with which a receiver reproduces the original signal, capacity refers to the maximum number of signals a receiver can handle, and selectivity refers to a receiver's ability to separate and tune in to a specific signal while rejecting others. Therefore, sensitivity is the most appropriate characteristic for a receiver's ability to reproduce the signal of a weak station.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 is a measure of how faithfully the receiver can reproduce the original signal without distortion or loss of information. A receiver with high fidelity will be able to accurately reproduce the input signal, while a receiver with low fidelity may introduce distortions or lose some of the original information. Capacity, sensitivity, and selectivity are not directly related to the accuracy of signal reproduction, making fidelity the correct answer.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 referred to as a transceiver. This device is capable of both transmitting and receiving signals, making it a versatile and efficient tool for communication purposes. By integrating these functionalities into a single unit, a transceiver simplifies the setup and operation of communication systems, reducing the need for separate transmitter and receiver units.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 correct answer is Copper. The question is asking about the type of loss caused by the resistance of the conductor material in a transmission line. Copper is a commonly used conductor material, and it has a certain resistance. This resistance leads to power loss in the form of heat, known as copper loss.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, resulting in increased resistance and power loss. As the frequency increases, the skin depth decreases, causing more current to flow near the surface of the conductor. This leads to higher resistance and increased skin-effect loss. Therefore, the frequency of the current is a determining factor in the amount of skin-effect loss experienced.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. Leakage loss occurs when some of the electrical energy is lost as heat due to the flow of current through the dielectric material. By using a high-resistance dielectric, the flow of current is reduced, resulting in lower leakage loss. This helps to improve the efficiency of the transmission line and minimize power losses. Thinner or thicker conductors do not directly affect leakage loss, and using a very low-resistance dielectric would actually increase leakage loss.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 better shielding and protection against interference compared to other options like flexible coaxial cable or twin lead. The rigid structure of the metal tube helps maintain the integrity of the signal being transmitted, making it suitable for applications that require high frequencies and low signal loss. Waveguide, on the other hand, is a different type of transmission line that uses a hollow metal tube to guide electromagnetic waves.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
A waveguide is a type of transmission line that is used when the frequencies of the signals being transmitted are very high, resulting in very short wavelengths. This is because waveguides are designed to efficiently transmit electromagnetic waves with high frequencies and short wavelengths, which cannot be effectively transmitted through traditional transmission lines. By using a waveguide, the signals can be contained and guided along the structure, allowing for efficient transmission at these high frequencies.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
This statement is false because the outer surface of waveguides will not arc from being very slightly damaged. Arcing occurs when there is a high voltage breakdown across a gap, but waveguides are designed to handle high power without arcing. Therefore, this statement is not true and is the exception among the given statements concerning waveguides.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 its 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 work together to determine how well the transmission line can transmit signals without distortion or loss.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 based on the wave equation, where wavelength (λ) is equal to the speed of the wave divided by the frequency. Therefore, if the frequency increases, the wavelength must decrease in order to maintain a constant speed.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 can be converted to 250 million hertz (Hz). The speed of light is approximately 300,000,000 meters per second. Dividing the speed of light by the frequency gives us a wavelength of 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 in such a way that there are no reflected waves. This means that the entire energy of the signal is transmitted without any portion being reflected back. In a nonresonant transmission line, the impedance is matched, allowing for efficient transfer of power. Therefore, there are no reflected waves in a nonresonant transmission line.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 the line is not connected to any load or device at the end. In this scenario, the signal will not be properly absorbed or reflected back, causing significant signal loss. The open termination prevents the signal from being effectively transmitted along the line, resulting in a weakened or distorted signal. 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 transmitter to receiver. This means that they do not require any obstacles or interruptions to propagate and can travel long distances without significant attenuation. Unlike other types of waves, direct waves do not rely on bouncing off the Earth's surface or being refracted by the atmosphere. Instead, they maintain a straight path, allowing for efficient long-distance communication.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
Radio waves that travel near the Earth's surface are called ground waves. These waves propagate by hugging the Earth's surface and following its curvature, allowing them to travel for long distances. Ground waves are commonly used for broadcasting and communication purposes, as they can easily penetrate buildings and other obstacles.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 refers to its ability to conduct electrical currents. In the context of this question, it is being determined by the type of atmospheric conditions at the time of transmission. The conductivity of the Earth can be influenced by factors such as air and moisture content in the propagation path. However, the primary determinant of Earth's conductivity is the composition of the soil and water in the propagation path. Soil and water can significantly impact the conductivity of the Earth, affecting the transmission of electrical currents.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 refers to the bending of radio waves as they pass from one medium to another with different densities. This phenomenon occurs due to the change in speed and direction of the waves when they enter a different medium.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 depends on atmospheric pressure and temperature. Atmospheric pressure affects the density of air, which in turn affects the speed of light passing through it. As the pressure increases, the density of air increases, causing the speed of light to decrease. Similarly, temperature also affects the density of air. As temperature increases, the density of air decreases, resulting in an increase in the speed of light. Therefore, both atmospheric pressure and temperature play a role in determining 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 15%. The radio horizon refers to the maximum distance at which radio waves can travel before being absorbed by the Earth's atmosphere, while the optical horizon refers to the maximum distance at which objects can be seen with the naked eye. Therefore, the radio horizon extends further than the optical horizon, and it is 15% farther away.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. It occurs when waves encounter an obstacle or an opening and bend around it, spreading outwards. This bending allows the waves to reach areas that are not directly in the line of sight, such as shadow regions. Reflection, scattering, and refraction do not specifically allow communication in shadow regions behind obstacles.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 (High Frequency) is the correct answer because it refers to the frequency range between 3 and 30 MHz, which is relatively low compared to UHF (Ultra High Frequency), SHF (Super High Frequency), and EHF (Extremely High Frequency). Precipitation, such as rain or snow, tends to have a greater impact on higher frequency ranges. Therefore, HF frequencies will experience little effect from precipitation compared to the other options.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 where radio waves are guided through the air between two layers of the atmosphere. This allows for long-distance communication without the need for satellite or other infrastructure. Channeling, guiding, and piping do not accurately describe this specific process of radio wave propagation.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 areas beyond the line-of-sight. Refraction occurs due to the variation in the density of the atmosphere, causing the radio waves to change direction and be able to communicate over longer distances. Reflection, Earth's conductivity, and atmospheric charge do not play a significant role in sky-wave propagation's ability 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 a line perpendicular to the surface of the ionosphere. It determines how the wave will be reflected, refracted, or absorbed by the ionosphere. The angle of incidence is an important factor in understanding how radio waves propagate through the ionosphere and is used in various applications such as radio communication and radar systems.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. This means that when the radio waves approach the ionosphere at a very low angle, they are absorbed by the ionosphere before they can be refracted or bent back towards the Earth's surface. This absorption prevents the radio waves from being reflected back to the Earth and instead they are lost or dissipated in the ionosphere.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. Sky-wave propagation refers to the reflection and refraction of radio waves by the ionosphere, allowing them to travel long distances. The critical frequency is the maximum frequency that can be refracted back to Earth by the ionosphere. Frequencies higher than the critical frequency cannot be refracted and instead pass through the ionosphere into space. Therefore, they are passed into space rather than being returned to Earth or refracted by the F2 layer.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 the transmission of data or signals is most efficient and effective. It is also known as the optimum traffic frequency because it represents the ideal frequency for transmitting traffic or data. The other options mentioned in the question, such as outbound traffic frequency and optimum tropospheric frequency, do not accurately describe the concept of FOT. Therefore, the correct answer is optimum traffic frequency.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 an area where no signals are received in sky- and ground-wave propagation. This occurs when the signal is too far for ground-wave propagation and not far enough for sky-wave propagation to occur. In this zone, the signal is neither reflected back to the Earth nor able to reach the receiver directly, resulting in no signal reception.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 when a transmitted signal takes multiple paths during transmission. This can happen due to reflections, refractions, or diffractions in the environment. As a result, the receiver receives multiple versions of the signal at slightly different times and amplitudes. Multipathing can cause interference, signal distortion, and reduced signal quality. It is a common issue in wireless communication systems, especially in urban areas with tall buildings and obstacles that cause signal reflections.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. These layers are the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. Each layer has its own unique characteristics and plays a vital role in the Earth's climate and weather patterns. The troposphere is the lowest layer and is where weather occurs, while the exosphere is the outermost layer and gradually transitions into space.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
Ionization is the process in which high-energy ultraviolet light waves from the sun enter the ionospheric region of the atmosphere and collide with gas atoms, causing them to lose or gain electrons and become ions. This process increases the number of ions in the atmosphere, leading to ionization.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 in the atmosphere combine with electrons to form neutral molecules. This process is dependent on the time of day (TOD) because the concentration of ions and electrons in the atmosphere varies throughout the day. During the day, there is more sunlight and ionizing radiation, which leads to the production of more ions and electrons. As the day progresses and sunlight decreases, the concentration of ions and electrons decreases as well. 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 of the ionosphere is the most important for high-frequency (HF) communications. This layer is located between 150 and 400 km above the Earth's surface and is responsible for reflecting HF radio waves back to the Earth. It is the highest ionospheric layer and has the highest electron density, allowing it to refract and reflect HF signals over long distances. This makes it crucial for long-range HF communication, such as international broadcasting and long-distance radio transmissions.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
During winter, the air is colder and denser, which leads to a wider range of critical frequencies. The colder air also has less moisture, resulting in less absorption of all frequencies. This combination of factors allows sound waves to travel further and with less attenuation, making winter the season with the 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 caused by intense magnetic activity, which inhibits the flow of heat from the sun's interior, resulting in cooler temperatures and reduced brightness. Sunspots can vary in size and can last from a few days to several months. They are closely monitored by scientists as they are indicators of solar activity and can have an impact on Earth's climate and communication systems.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 spots on the surface of the sun that are caused by intense magnetic activity. These spots appear and disappear over time, following a cycle of approximately 11 years. During the peak of the cycle, the number of sunspots is at its highest, and during the minimum, the number is at its lowest. This 11-year cycle is known as the solar cycle and is closely linked to other solar phenomena, such as solar flares and coronal mass ejections.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
An antenna is used in a basic communication system to convert radio frequency (RF) current oscillation into electric and magnetic fields of force. It acts as a transducer, converting electrical signals into electromagnetic waves that can be transmitted and received. The antenna plays a crucial role in transmitting and receiving signals efficiently and effectively in a communication system.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. Alternating current is used in radio transmission because it can be easily transformed into different voltages, allowing for the efficient transmission of signals over long distances. This concept is essential for the functioning of radio communication systems.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 cycles per second (cps), the magnetic fields around a wire do not have enough time to collapse completely between alternations. This means that the magnetic field does not have enough time to fully dissipate before the next alternation occurs. As a result, the magnetic field will not collapse completely and will persist between alternations at this frequency.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 waves are a form of electromagnetic radiation that is created by the antenna. Electromagnetic radiation is a type of energy that detaches from the antenna and travels through space at great distances. It does not require a medium to propagate and can travel through a vacuum. Therefore, the correct answer is radiation.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 degradation caused by atmospheric conditions and other obstacles. By transmitting right-hand circular polarization and receiving left-hand circular polarization, the terminals can effectively communicate with satellites and ensure reliable signal transmission.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 effective in radiating radio signals within a certain range around that frequency. This range is usually within a percentage of plus or minus the designed frequency. Therefore, the correct answer is 2, indicating that the resonant antenna is usually within a range of plus or minus 2% of its designed frequency for effective signal radiation.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 correct answer is 9.8–10.2 MHz. This is because the frequency range of a resonant antenna is typically slightly higher and lower than its design frequency. In this case, the design frequency is 10 MHz, so the frequency range would be 9.8–10.2 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 is the primary or base frequency at which the antenna can vibrate or oscillate most easily. It is the fundamental mode of vibration for the antenna and determines its resonant characteristics.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 receive and transmit signals equally well. It means that the antenna's characteristics remain the same regardless of whether it is used for receiving or transmitting signals. This property is essential for efficient communication systems as it allows for bidirectional communication without the need for separate antennas for transmitting and receiving.Rate this question:
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