Z3D153 Volume 2 Ure

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1/100 Questions

Which US government agency divides the radio frequency spectrum into different bands?
- Federal Aviation Agency.
- American National Standard Institute.
- Federal Communications Commission (FCC).
- Institute of Electrical & Electronics Engineers, Inc.

About This Quiz

Z3D153 Volume 2 URE assesses knowledge on US frequency regulations, high-frequency transmission modes, jamming vulnerabilities, and receiver characteristics. It's vital for professionals in telecommunications and radio frequency engineering.

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2.

High-frequency (HF) transmissions are normally conducted in which two operating modes?
- Frequency modulation (FM) and independent sidebands (ISB).
- Continuous wave (CW) and amplitude modulation (AM).
- Single side band (SSB) and FM.
- SSB and ISB.
Correct Answer

A. 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.

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3.

Which frequency band is most susceptible to jamming?
- Low frequency (LF)
- Medium frequency (MF).
- High frequency (HF).
- Very high frequency (VHF).
Correct Answer

A. 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.

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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
- Fidelity.
- Capacity.
- Sensitivity
- Selectivity.
Correct Answer

A. Sensitivity

Explanation

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.

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5.

The ability of a receiver to reproduce the input signal accurately is characteristic of its
- Fidelity
- Capacity
- Sensitivity.
- Selectivity
Correct Answer

A. Fidelity

Explanation

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.

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6.

A combination transmitter and receiver, built as a single unit and shares common tuned circuits, is called a
- Transmitter.
- Transceiver.
- Receiver
- Coupler.
Correct Answer

A. 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.

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7.

Conductor material resistance in a transmission line leads to this type of loss.
- Copper.
- Radiation
- Inductive
- 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.

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1
8.

The amount of skin-effect loss is directly proportional to the
- Line length
- Frequency
- Voltage level
- Resistive loss
Correct Answer

A. Frequency

Explanation

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.

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9.

Leakage loss in a transmission line is minimized by using a
- Thinner conductor
- thicker conductor
- Very low-resistance dielectric
- Very high-resistance dielectric.
Correct Answer

A. 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.

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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
- Flexible coaxial cable.
- Rigid coaxial cable.
- Waveguide
- Twin lead
Correct Answer

A. 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.

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11.

A waveguide is a type of transmission line that you would use
- When the frequencies are so high that their wavelength is miniscule.
- to transmit on frequencies too low for ground propagation.
- for high power at frequencies up to 30 megahertz (MHz) primarily.
- 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.

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12.

All statements concerning waveguides are true except
- Their outer surface will arc from being very slightly damaged.
- Their conductive material construction is easily dented.
- Their effectiveness is hindered by moisture.
- 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.

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13.

Which two transmission line properties determine its characteristic impedance (ZO)?
- Inductance and resistance.
- Inductance and capacitance
- Resistance and capacitance.
- Length and type of shielding.
Correct Answer

A. Inductance and capacitance

Explanation

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.

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14.

This is the correct statement concerning a wavelength.
- Wavelength is inversely related to frequency.
- Wavelength is directly related to frequency.
- Wavelength is determined by the line length.
- 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.

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15.

Determine the wavelength of a 250 megahertz (MHz) signal.
- 12.0 meters
- 3.0 meters
- 1.5 meters
- 1.2 meters
Correct Answer

A. 1.2 meters

Explanation

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.

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16.

A nonresonant transmission line is one with
- Reflected waves
- No reflected waves
- Maximum voltage across its open termination.
- Maximum voltage across its shorted termination.
Correct Answer

A. No reflected waves

Explanation

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."

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17.

When discussing resonant and nonresonant transmission lines,
- Resonant lines are often referred to as flat lines
- Maximum power transfer results from a resonant line
- Maximum power transfer results from a nonresonant line
- Significant loss and damage to equipment results from using a nonresonant line.
Correct Answer

A. Maximum power transfer results from a nonresonant line
18.

This will likely result if a transmission line is terminated in an open.
- Signal loss would be negligible.
- Signal loss would be significant.
- Current would be maximum at the termination.
- Voltage would be minimum at the termination
Correct Answer

A. 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.

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19.

Direct waves are radio waves that travel
- Long distances with few interruptions.
- From point to point along the Earth’s surface.
- No more than 20 miles to the receive antenna
- Through the air in a straight line from transmitter to receiver
Correct Answer

A. Through the air in a straight line from transmitter to receiver

Explanation

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.

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20.

Radio waves that travel near the Earth’s surface are called
- Earth waves
- Global waves
- Ground waves
- Terrestrial waves
Correct Answer

A. Ground waves

Explanation

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.

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21.

The Earth’s conductivity is determined by the type of
- Atmospheric conditions at the time of transmission.
- Air and moisture content in the propagation path.
- Soil and water in the propagation path.
- soil and air in the propagation path
Correct Answer

A. 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.

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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
- Diffusion
- Diffraction
- Refraction
- Reflection
Correct Answer

A. Refraction

Explanation

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.

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23.

The refractive index of air depends on moisture
- Atmospheric pressure, and temperature.
- atmospheric pressure, and frequency.
- Receive signal level, and temperature
- 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.

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24.

When comparing the radio and optical horizons, which one is farther away and by what percentage?
- Optical; 15
- Radio; 15.
- Optical; 33.
- Radio; 33
Correct Answer

A. 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.

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25.

Which process permits communication in shadow regions behind obstacles?
- Reflection
- Scattering
- Refraction
- Diffraction
Correct Answer

A. Diffraction

Explanation

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.

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26.

Which frequency range will show little effect from precipitation?
- HF
- UHF
- SHF
- EHF
Correct Answer

A. HF

Explanation

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.

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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
- Channeling
- Guiding
- Ducting
- Piping
Correct Answer

A. Ducting

Explanation

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.

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28.

Which condition gives sky-wave propagation its ability to communicate beyond the optical line-of-sight (LOS)?
- Refraction
- Reflection
- Earth’s conductivity
- Atmospheric charge.
Correct Answer

A. Refraction

Explanation

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.

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29.

The angle at which a radio wave enters the ionosphere is known as the
- Skip angle
- Critical angle
- Angle of entrance
- Angle of incidence
Correct Answer

A. Angle of incidence

Explanation

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.

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30.

There are several critical sky-wave propagation angles and frequencies. Radio waves that angle too low are
- Refracted
- Returned to Earth
- Absorbed before refraction occurs
- Passed through the ionosphere into space
Correct Answer

A. Absorbed before refraction occurs

Explanation

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.

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31.

In sky-wave propagation, frequencies higher than the critical frequency are
- Returned to Earth
- Passed into space
- The most desirable
- Refracted by the F2 player
Correct Answer

A. Passed into space

Explanation

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.

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32.

The term frequency of optimum transmission (FOT) is also referred to as the
- Outbound traffic frequency
- Optimum tropospheric frequency
- Optimum traffic frequency.
- Frequency of outbound transmission.
Correct Answer

A. 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.

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33.

In sky- and ground-wave propagation, the area of silence where no signals are received is known as the
- Propagation distance
- Skip distance
- Dead zone
- Skip zone
Correct Answer

A. Skip zone

Explanation

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.

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34.

This occurs when a transmitted signal travels over two or more separate paths during transmission
- Skip effects
- Modulation
- Multipathing
- Magneton splitting
Correct Answer

A. Multipathing

Explanation

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.

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35.

How many layers make up the Earth’s atmosphere?
- 2
- 3
- 4
- 5
Correct Answer

A. 5

Explanation

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.

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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.
- Ionization
- Modulation
- Conductivity
- Recombination
Correct Answer

A. Ionization

Explanation

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.

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37.

The atmospheric recombination process is dependent on the
- Season
- Time of day (TOD)
- Regular variation
- Irregular variations
Correct Answer

A. 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.

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38.

Which layer of the ionosphere is most important for high-frequency (HF) communications?
- D
- E
- F
- Topside
Correct Answer

A. F

Explanation

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.

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39.

During which season do we have the wider range of critical frequencies and less absorption of all frequencies?
- Fall
- Winter
- Spring
- Summer
Correct Answer

A. Winter

Explanation

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.

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40.

As ionospheric solar variations, sunspots are disturbances that appear and disappear
- In the sun’s atmosphere
- On the sun’s surface.
- In the ionosphere.
- Beneath the sun’s surface.
Correct Answer

A. 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.

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41.

On which regular ionospheric variation do sunspots occur?
- 11-day cycle
- 11-week cycle
- 11-month cycle
- 11-year cycle.
Correct Answer

A. 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.

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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.
- Antenna
- Transmitter
- Coupler
- Transmission lines
Correct Answer

A. Antenna

Explanation

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.

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43.

The concept where alternating current (AC) changes in magnitude, and reverses its direction during each cycle, is
- An unproven hypothesis.
- The definition of propagation
- What makes radio transmission possible.
- What led to the discovery of direct current (DC).
Correct Answer

A. 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.

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44.

At which point do magnetic fields around a wire no longer have time to collapse completely between alternations?
- 60 cycles per second (cps).
- 120 cps.
- 10,000 cps.
- 15,000 cps
Correct Answer

A. 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.

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1
45.

In radio-wave creation, which type of field detaches from the antenna and travels through space at great distances?
- Radiation
- Induction
- Gravitational
- Electromotive
Correct Answer

A. Radiation

Explanation

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.

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46.

Which types of polarization do most satellite communication terminals transmit and receive?
- Transmit horizontal and receive vertical polarizations
- Transmit vertical and receive horizontal polarizations.
- Transmit right-hand circular and receive left-hand circular polarizations.
- Transmit left-hand circular and receive right-hand circular polarizations
Correct Answer

A. 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.

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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?
- 1
- 2
- 3
- 4
Correct Answer

A. 2

Explanation

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.

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48.

The design frequency of a resonant antenna is 10 megahertz (MHz). What will be its frequency range?
- 8–10 MHz.
- 9–11 MHz
- 9.5–10.5 MHz
- 9.8–10.2 MHz.
Correct Answer

A. 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.

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49.

The lowest frequency at which an antenna resonates is known as its
- Standing wave
- Fundamental
- Resonation
- Primary
Correct Answer

A. Fundamental

Explanation

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.

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Quiz Review Timeline (Updated): Mar 20, 2023 +

Our quizzes are rigorously reviewed, monitored and continuously updated by our expert board to maintain accuracy, relevance, and timeliness.

Current Version
Mar 20, 2023

Quiz Edited by
ProProfs Editorial Team
Mar 28, 2017

Quiz Created by
Trevormayer88

Z3D153 Volume 2 Ure

Which US government agency divides the radio frequency spectrum into different bands?

Quiz Preview

High-frequency (HF) transmissions are normally conducted in which two operating modes?

Which frequency band is most susceptible to jamming?

The ability of a receiver to reproduce the signal of a very weak station is characteristic of a receiver’s

The ability of a receiver to reproduce the input signal accurately is characteristic of its

A combination transmitter and receiver, built as a single unit and shares common tuned circuits, is called a

Conductor material resistance in a transmission line leads to this type of loss.

The amount of skin-effect loss is directly proportional to the

Leakage loss in a transmission line is minimized by using a

A transmission line that consists of a center conductor, placed inside a rigid metal tube that functions as the outer shield, is called

A waveguide is a type of transmission line that you would use

All statements concerning waveguides are true except

Which two transmission line properties determine its characteristic impedance (ZO)?

This is the correct statement concerning a wavelength.

Determine the wavelength of a 250 megahertz (MHz) signal.

A nonresonant transmission line is one with

When discussing resonant and nonresonant transmission lines,

This will likely result if a transmission line is terminated in an open.

Direct waves are radio waves that travel

Radio waves that travel near the Earth’s surface are called

The Earth’s conductivity is determined by the type of

This term is used to describe radio waves that bend as they travel from one medium to another that has different density

The refractive index of air depends on moisture

When comparing the radio and optical horizons, which one is farther away and by what percentage?

Which process permits communication in shadow regions behind obstacles?

Which frequency range will show little effect from precipitation?

Line-of-sight (LOS) radio waves that are guided through the air between two layers of the atmosphere are known as

Which condition gives sky-wave propagation its ability to communicate beyond the optical line-of-sight (LOS)?

The angle at which a radio wave enters the ionosphere is known as the

There are several critical sky-wave propagation angles and frequencies. Radio waves that angle too low are

In sky-wave propagation, frequencies higher than the critical frequency are

The term frequency of optimum transmission (FOT) is also referred to as the

In sky- and ground-wave propagation, the area of silence where no signals are received is known as the

This occurs when a transmitted signal travels over two or more separate paths during transmission

How many layers make up the Earth’s atmosphere?

This occurs when high-energy ultraviolet light waves from the sun enter the ionospheric region of the atmosphere and strike the gas atoms.

The atmospheric recombination process is dependent on the

Which layer of the ionosphere is most important for high-frequency (HF) communications?

During which season do we have the wider range of critical frequencies and less absorption of all frequencies?

As ionospheric solar variations, sunspots are disturbances that appear and disappear

On which regular ionospheric variation do sunspots occur?

In a basic communication system, this is used to convert radio frequency (RF) current oscillation into electric and magnetic fields of force.

The concept where alternating current (AC) changes in magnitude, and reverses its direction during each cycle, is

At which point do magnetic fields around a wire no longer have time to collapse completely between alternations?

In radio-wave creation, which type of field detaches from the antenna and travels through space at great distances?

Which types of polarization do most satellite communication terminals transmit and receive?

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?

The design frequency of a resonant antenna is 10 megahertz (MHz). What will be its frequency range?

The lowest frequency at which an antenna resonates is known as its