Comm Stuff Volume 2 UREs

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  • 1/101 Questions

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

    • Transmitter.
    • Transceiver.
    • Receiver.
    • Coupler.
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About This Quiz

This quiz titled 'comm stuff volume 2 UREs' assesses knowledge on US radio frequency management, HF transmission modes, receiver characteristics, and the integration of transceivers. It is designed for learners in military communications, enhancing both practical skills and theoretical understanding.

Comm Stuff Volume 2 UREs - Quiz

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  • 2. 

    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
    Radio waves that travel near the Earth's surface are called ground waves. This is because these waves propagate by hugging the surface of the Earth and following its curvature. Ground waves are able to travel long distances and are commonly used for broadcasting purposes. They are also able to penetrate buildings and other obstacles, making them suitable for communication in urban areas.

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  • 3. 

    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 occurs when a transmitted signal travels over two or more separate paths during transmission. This can happen due to reflections, refractions, or diffractions of the signal. As a result, multiple copies of the signal reach the receiver at slightly different times, causing interference and signal degradation. Multipathing is a common phenomenon in wireless communication systems and can be mitigated using techniques like equalization and diversity reception.

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  • 4. 

    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, it causes the atoms to lose or gain electrons, resulting in the formation of ions. This process is known as ionization.

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  • 5. 

    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. Sunspots are dark, cooler areas on the sun's photosphere caused by intense magnetic activity. They are temporary phenomena that can last from a few hours to several weeks before fading away. These sunspots are visible as dark spots on the sun's surface and can be observed using telescopes equipped with solar filters. The presence and movement of sunspots provide valuable information about the sun's magnetic field and can also affect space weather conditions on Earth.

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  • 6. 

    Which type of antenna radiates radio energy equally well in all directions?

    • Omni-directional.

    • Uni-directional.

    • Bi-directional.

    • Directional.

    Correct Answer
    A. Omni-directional.
    Explanation
    An omni-directional antenna radiates radio energy equally well in all directions. This means that it has a 360-degree radiation pattern, allowing it to transmit and receive signals from all directions without the need for manual adjustment. This type of antenna is commonly used in applications where a wide coverage area is desired, such as in broadcast radio and Wi-Fi networks. Uni-directional, bi-directional, and directional antennas, on the other hand, have more focused radiation patterns and are used in situations where signals need to be transmitted or received in specific directions.

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  • 7. 

    This is the best way to orient line-of-sight (LOS) antennas.

    • Toward the true north bearing.

    • Away from the receiving station.

    • Away from the magnetic north bearing.

    • In a straight path to the receiving station.

    Correct Answer
    A. In a straight path to the receiving station.
    Explanation
    The best way to orient line-of-sight (LOS) antennas is in a straight path to the receiving station. This ensures that there is a direct and unobstructed line of sight between the transmitting and receiving antennas, maximizing signal strength and minimizing interference. Orienting the antennas toward the true north or away from the receiving station or magnetic north bearing may not necessarily guarantee a clear line of sight and could result in signal degradation.

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  • 8. 

    The process of unscrambling encrypted information so that it is intelligible is known as

    • Decryption.

    • Encryption.

    • Cryptography.

    • Cryptanalysis.

    Correct Answer
    A. Decryption.
    Explanation
    Decryption refers to the process of converting encrypted information back into its original, intelligible form. It involves using a decryption key or algorithm to reverse the encryption process and make the data readable again. Encryption, on the other hand, is the process of converting plain text into ciphertext to protect it from unauthorized access. Cryptography is the broader field that encompasses both encryption and decryption techniques. Cryptanalysis, however, refers to the study and analysis of cryptographic systems with the aim of breaking or bypassing their security measures.

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  • 9. 

    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. The rigid structure of the metal tube provides stability and protection to the center conductor, making it suitable for applications that require durability and resistance to external interference. Unlike flexible coaxial cables, which have a flexible outer jacket, rigid coaxial cables are less prone to bending or deformation, making them ideal for installations where the cable needs to maintain its shape and position. Waveguides and twin leads are different types of transmission lines that have distinct structures and characteristics.

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  • 10. 

    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. This is because radio waves are a form of electromagnetic radiation that can be generated and transmitted using AC. The changing magnitude and direction of AC allows for the creation and propagation of electromagnetic waves, which can then be received and decoded by radio receivers.

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  • 11. 

    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
    In radio-wave creation, the type of field that detaches from the antenna and travels through space at great distances is radiation. Radiation refers to the emission of energy as electromagnetic waves or as moving subatomic particles, such as electrons. In the context of radio waves, radiation is the process by which the energy from the antenna is propagated outward in the form of electromagnetic waves, which can travel through space and be received by other devices.

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  • 12. 

    The ability of an antenna to both receive and transmit equally well is known as the antenna’s

    • Bandwidth.

    • Resonance.

    • Reciprocity.

    • Effectiveness.

    Correct Answer
    A. Reciprocity.
    Explanation
    Reciprocity refers to the ability of an antenna to both receive and transmit signals equally well. It means that the characteristics of an antenna remain the same regardless of whether it is used for receiving or transmitting. This property is important in various communication systems as it allows for efficient and reliable signal transmission and reception. Bandwidth refers to the range of frequencies over which an antenna can operate effectively. Resonance refers to the frequency at which an antenna operates most efficiently. Effectiveness is a general term that does not specifically describe the ability of an antenna to receive and transmit signals equally well.

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  • 13. 

    Which statement best identifies the requirements for two transceivers to establish HAVE QUICK (HQ) communications?

    • They must be the same model number.

    • They must be the same version of transceiver.

    • They must be use the same encryption variables.

    • They must have the same word of day (WOD) and time of day (TOD).

    Correct Answer
    A. They must have the same word of day (WOD) and time of day (TOD).
    Explanation
    The requirement for two transceivers to establish HAVE QUICK (HQ) communications is that they must have the same word of day (WOD) and time of day (TOD). This ensures that both transceivers are synchronized and can communicate effectively using the same encryption variables. The other statements, such as being the same model number or version of transceiver, are not mentioned as requirements for establishing HQ communications.

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  • 14. 

    The common name for the method of changing encryption keys over the radio channel in a two-way radio system is called

    • Over-the-air rekeying (OTAR).

    • Asymmetric.

    • Symmetric.

    • Off-line.

    Correct Answer
    A. Over-the-air rekeying (OTAR).
    Explanation
    Over-the-air rekeying (OTAR) is the common name for the method of changing encryption keys over the radio channel in a two-way radio system. This process allows for secure and efficient key management by enabling the remote distribution of encryption keys without the need for physical contact or manual intervention. OTAR ensures that the encryption keys used for secure communication are regularly updated, enhancing the overall security of the radio system.

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  • 15. 

    Which type of site configuration was designed to provide coverage for a small geographical area?

    • Single-site.

    • Multi-site.

    • Simulcast.

    • Multicast.

    Correct Answer
    A. Single-site.
    Explanation
    Single-site configuration is designed to provide coverage for a small geographical area. This configuration involves a single base station or repeater site that covers the entire area, ensuring that communication signals are strong and reliable within that limited range. This type of configuration is commonly used in small towns, campuses, or industrial complexes where a single site can effectively cover the entire area without the need for multiple sites or repeaters.

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  • 16. 

    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.

    Correct Answer
    A. 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. This division is necessary to allocate specific frequencies for various uses such as broadcasting, telecommunications, and wireless communication. The FCC ensures that different users, including government agencies, private companies, and individuals, can access the spectrum without interference. By regulating and managing the allocation of radio frequencies, the FCC promotes efficient and effective use of the spectrum for communication purposes.

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  • 17. 

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

    • Returned to Earth.

    • Passed into space.

    • The most desirable.

    • Refracted by the F2 layer.

    Correct Answer
    A. Passed into space.
    Explanation
    In sky-wave propagation, frequencies higher than the critical frequency are passed into space. Sky-wave propagation refers to the transmission of radio waves from a ground-based transmitter to a receiver by reflecting them off the ionosphere. The critical frequency is the maximum frequency that can be reflected back to Earth by the ionosphere. Frequencies higher than the critical frequency are not reflected back and instead continue to travel into space. Therefore, they are passed into space rather than being returned to Earth or refracted by the F2 layer.

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  • 18. 

    Which type of polarization is used to radiate a signal using a helical satellite antenna?

    • Horizontal.

    • Vertical.

    • Circular.

    • Linear.

    Correct Answer
    A. Circular.
    Explanation
    Circular polarization is used to radiate a signal using a helical satellite antenna. This type of polarization is achieved by combining both horizontal and vertical components of the electromagnetic wave, resulting in a rotating electric field. Circular polarization is advantageous for satellite communication as it helps minimize the effects of signal fading and interference caused by changes in the orientation of the receiving antenna.

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  • 19. 

    When siting a radio station, which type of foliage would have a more adverse effect on radio-wave propagation?

    • Broadleaf trees.

    • Evergreen trees.

    • Swamp grass.

    • Sagebrush.

    Correct Answer
    A. Broadleaf trees.
    Explanation
    Broadleaf trees would have a more adverse effect on radio-wave propagation compared to evergreen trees, swamp grass, and sagebrush. This is because broadleaf trees have denser foliage with larger and more numerous leaves, which can absorb and scatter radio waves more effectively. As a result, the presence of broadleaf trees can cause signal attenuation and interference, leading to a weaker and less reliable radio signal. On the other hand, evergreen trees, swamp grass, and sagebrush have less dense foliage, allowing radio waves to pass through with less obstruction.

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  • 20. 

    This is the most effective type of antennas in mountainous terrain that has a mountain between you and the distant end.

    • Whip.

    • Dipole.

    • Discone.

    • Near-vertical incidence sky-wave.

    Correct Answer
    A. Near-vertical incidence sky-wave.
    Explanation
    In mountainous terrain with a mountain obstructing the path between the antenna and the distant end, the most effective type of antenna is the near-vertical incidence sky-wave (NVIS) antenna. NVIS antennas are designed to transmit and receive signals at high angles, allowing them to bounce off the ionosphere and reach shorter distances. This makes them ideal for communication in areas with obstacles like mountains, where signals cannot be transmitted directly. Whip, dipole, and discone antennas are not specifically designed for mountainous terrain and may not be as effective in this scenario.

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  • 21. 

    How long is each word-of-day (WOD) used with the HAVE QUICK II (HQII) communications multiple word-of-day (MWOD)?

    • Until manually changed.

    • 3 days.

    • 48 hours.

    • 24 hours.

    Correct Answer
    A. 24 hours.
    Explanation
    The word-of-day (WOD) used with the HAVE QUICK II (HQII) communications multiple word-of-day (MWOD) is changed every 24 hours. This means that the WOD is valid for a period of 24 hours before it needs to be manually changed.

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  • 22. 

    Which statement is not a benefit of having a trunking network?

    • Selective radio inhibit.

    • Faster system access.

    • Unbalanced channel loads.

    • Better channel efficiency.

    Correct Answer
    A. Unbalanced channel loads.
    Explanation
    Unbalanced channel loads is not a benefit of having a trunking network. Trunking networks allow for efficient utilization of available channels by dynamically assigning them to users as needed. This ensures that channels are evenly distributed and prevents overloading on any particular channel. Unbalanced channel loads would indicate an inefficient distribution of channel usage, which is not desirable in a trunking network.

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  • 23. 

    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 frequency band that is most susceptible to jamming. HF signals can travel long distances and are used for long-range communication, making them more vulnerable to interference and intentional jamming. Additionally, HF signals can be easily disrupted by atmospheric conditions and natural phenomena such as solar flares, further increasing their susceptibility to jamming.

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  • 24. 

    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
    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 prevent such breakdowns. The other statements are true: waveguides can be easily dented due to their conductive material construction, their effectiveness can be hindered by moisture, and they can be destroyed by corrosion.

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  • 25. 

    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 in such a way that there are no reflected waves. This means that all the energy that is sent down the line is completely absorbed by the load at the end of the line, with no energy bouncing back towards the source. This is achieved by matching the impedance of the transmission line with the impedance of the load. As a result, there is no voltage or current wave that travels back along the line, indicating the absence of reflected waves.

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  • 26. 

    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
    Line-of-sight (LOS) radio waves that are guided through the air between two layers of the atmosphere are known as ducting. Ducting occurs when atmospheric conditions cause radio waves to be trapped and guided along a specific path, allowing them to travel much farther than they would in normal conditions. This phenomenon is commonly observed in certain weather conditions, such as temperature inversions, where the air near the ground is cooler than the air above it, creating a duct or channel for the radio waves to follow.

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  • 27. 

    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 determined by its sensitivity. A receiver with high sensitivity can detect and amplify weak signals, allowing it to pick up and reproduce the signal of a weak station. Fidelity refers to the accuracy and faithfulness with which a receiver reproduces the original signal, capacity refers to the maximum amount of information a receiver can handle, and selectivity refers to the ability to separate and filter out unwanted signals. However, in this context, the most relevant characteristic is sensitivity.

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  • 28. 

    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 is 10 megahertz (MHz), which means that it is specifically designed to operate at this frequency. However, due to various factors such as manufacturing tolerances and environmental conditions, the actual operating frequency of the antenna may vary slightly. Therefore, the frequency range of the resonant antenna is expected to be within a small range around the design frequency. In this case, the correct answer is 9.8–10.2 MHz, which represents a narrow range of frequencies close to the design frequency of 10 MHz.

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  • 29. 

    This is one of the simplest and most functional antennas in use.

    • Quarter-wave vertical.

    • Half-wave dipole.

    • Inverted-V.

    • GRA–4.

    Correct Answer
    A. Half-wave dipole.
    Explanation
    The half-wave dipole is a popular and effective antenna design that is widely used due to its simplicity and functionality. It consists of two equal-length conductors, with each conductor being a quarter-wavelength long. This antenna is known for its balanced radiation pattern, which allows for efficient transmission and reception of electromagnetic waves. It is commonly used in radio and television broadcasting, as well as in amateur radio applications.

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  • 30. 

    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 wavelength increases, the frequency decreases, and vice versa. This relationship is based on the wave equation, where wavelength (λ) is equal to the speed of light (c) divided by the frequency (f). Since the speed of light is constant, if the wavelength increases, the frequency must decrease to maintain this equation. Therefore, wavelength and frequency have an inverse relationship.

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  • 31. 

    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 case, the signal will reflect back towards the source, causing interference and signal loss. This is because the open termination does not provide impedance matching, leading to a mismatch between the transmission line and the load. As a result, a significant amount of the signal will be lost, leading to significant signal loss.

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  • 32. 

    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, which affects the propagation of signals, is determined by the type of soil and water in the propagation path. Soil and water have different electrical properties that can impact the transmission of signals. The composition and moisture content of the soil and water can influence how well they conduct electricity, which in turn affects the propagation of signals through them.

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  • 33. 

    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
    When radio waves angle too low during sky-wave propagation, they are absorbed before refraction occurs. This means that the radio waves are absorbed by the ionosphere before they have a chance to be refracted back towards Earth. This absorption prevents the radio waves from being returned to Earth or passing through the ionosphere into space.

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  • 34. 

    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 faithfully the receiver can reproduce the original signal without distortion or loss of information. Capacity refers to the amount of information that can be transmitted or stored. Sensitivity refers to the ability of a receiver to detect weak signals. Selectivity refers to the ability of a receiver to separate desired signals from unwanted interference.

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  • 35. 

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

    • Copper.

    • Radiation.

    • Inductive.

    • Skin-effect.

    Correct Answer
    A. Copper.
    Explanation
    The correct answer is Copper. Copper is a conductor material commonly used in transmission lines. When current flows through the copper conductor, it encounters resistance, which leads to energy loss in the form of heat. This resistance is known as copper resistance or conductor resistance. Therefore, the presence of copper in a transmission line contributes to this type of loss.

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  • 36. 

    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 transmitter to receiver. This means that there are no obstacles or interruptions in the path of the waves. They do not bounce off the Earth's surface or any other objects, and they do not follow the curvature of the Earth. This allows direct waves to travel long distances without significant loss of signal strength. The statement "through the air in a straight line from transmitter to receiver" accurately describes the nature of direct waves.

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  • 37. 

    You should use this type of antenna to communicate over the horizon to an amphibious ship on the move or to a station up to 450 kilometers away.

    • Near-vertical incidence sky-wave.

    • Helical.

    • Inverted-V.

    • Inverted-L.

    Correct Answer
    A. Near-vertical incidence sky-wave.
    Explanation
    The near-vertical incidence sky-wave antenna is the most suitable choice for communicating over the horizon to an amphibious ship or a station up to 450 kilometers away. This type of antenna is designed to transmit and receive signals that are reflected off the ionosphere at near-vertical angles, allowing for long-distance communication. It is particularly effective for over-the-horizon communication as it utilizes the sky-wave propagation mode, which enables signals to be bent back towards the Earth's surface. This makes it a reliable option for reaching distant locations without the need for a direct line of sight.

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  • 38. 

    This type of antenna is used to transmit and receive microwave signals.

    • Horn.

    • Whip.

    • Helical.

    • Log-periodic.

    Correct Answer
    A. Horn.
    Explanation
    A horn antenna is commonly used to transmit and receive microwave signals. It has a flared shape, resembling a horn, which allows for efficient radiation and reception of electromagnetic waves. The flared structure helps to direct and focus the microwave signals, resulting in a high gain and improved performance. Horn antennas are widely used in various applications, including satellite communication, radar systems, and wireless networks, due to their ability to handle high frequencies and their directional properties.

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  • 39. 

    Electromagnetic (EM) deception, as it applies to electronic warfare (EW), is

    • Controlling the information an enemy receives.

    • Eliminating some, or all, of an adversary’s electronic defenses.

    • Conveying misleading information to an enemy through the deliberate radiation of EM energy.

    • Degrading, or interfering with, the enemy’s use of the EM spectrum to limit an enemy’s combat capabilities.

    Correct Answer
    A. Conveying misleading information to an enemy through the deliberate radiation of EM energy.
    Explanation
    The correct answer is conveying misleading information to an enemy through the deliberate radiation of EM energy. This explanation aligns with the concept of electromagnetic deception in electronic warfare. By deliberately emitting electromagnetic energy, one can create false signals or distort the enemy's perception of the electromagnetic spectrum, leading them to make incorrect decisions or take ineffective actions. This tactic aims to deceive and confuse the adversary rather than eliminating their defenses or limiting their combat capabilities.

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  • 40. 

    In high-frequency (HF) communications, your station’s automatic link establishment (ALE) self-address is the address

    • The user programmed for his or her station.

    • It shares with other members.

    • Of an unprogrammed station.

    • Of other stations in the net.

    Correct Answer
    A. The user programmed for his or her station.
    Explanation
    The correct answer is "the user programmed for his or her station." In high-frequency (HF) communications, the automatic link establishment (ALE) self-address refers to the address that the user has programmed for their own station. This address is unique to the user's station and is used for communication and identification purposes within the network.

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  • 41. 

    Which type of conventional land mobile radio (LMR) device maximizes the communications distance between lower-powered equipment items?

    • Mobile.

    • Portable.

    • Repeater.

    • Base station.

    Correct Answer
    A. Repeater.
    Explanation
    A repeater is a type of conventional land mobile radio (LMR) device that maximizes the communication distance between lower-powered equipment items. It receives signals transmitted by mobile or portable devices and retransmits them at a higher power, extending the range of communication. This allows for better coverage and improved communication between devices that have limited transmission power. A repeater acts as a relay station, enhancing the signal strength and increasing the distance over which communication can take place.

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  • 42. 

    Which Air Force instruction (AFI) requires communications squadrons to maintain installation notification and warning systems (INWS)?

    • AFI 10–2501, Air Force Emergency Management Program.

    • AFI 10–2801, Force Development Concepts.

    • AFI 33–115, Air Force Information Technology Service Management.

    • AFI 33–217, Voice Call Sign Program.

    Correct Answer
    A. AFI 10–2501, Air Force Emergency Management Program.
    Explanation
    The correct answer is AFI 10–2501, Air Force Emergency Management Program. This AFI specifically addresses the Air Force's Emergency Management Program, which includes the requirement for communications squadrons to maintain installation notification and warning systems (INWS). This AFI provides guidance and procedures for emergency management planning, response, and recovery, ensuring that the Air Force is prepared to effectively respond to and mitigate emergencies and disasters.

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  • 43. 

    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 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 of the waves, causing them to change direction. Diffusion refers to the spreading out of waves in different directions, while diffraction refers to the bending of waves around obstacles. Reflection occurs when waves bounce off a surface.

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  • 44. 

    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 because the angle of incidence refers to the angle at which a wave approaches a boundary between two mediums, in this case, the ionosphere. It is important to understand the angle of incidence as it determines how the wave will be refracted or reflected upon entering the ionosphere.

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  • 45. 

    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 electrons in the atmosphere combine to form neutral molecules. This process is influenced by various factors, including the time of day. During the daytime, the presence of sunlight and increased temperature enhances the recombination process. In contrast, during the nighttime, the absence of sunlight and lower temperatures hinder the recombination process. Therefore, the time of day (TOD) plays a crucial role in determining the rate and efficiency of atmospheric recombination.

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  • 46. 

    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
    During winter, the air is colder and denser, which leads to a wider range of critical frequencies and less absorption of all frequencies. This is because sound waves travel faster in colder air, allowing for a wider range of frequencies to be transmitted. Additionally, the colder air also reduces the amount of moisture and humidity, which can absorb sound waves. Therefore, winter is the season with the wider range of critical frequencies and less absorption of all frequencies.

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  • 47. 

    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
    In a basic communication system, the antenna is used to convert radio frequency (RF) current oscillation into electric and magnetic fields of force. The antenna acts as a transducer, transforming the electrical signals into electromagnetic waves that can be transmitted through space. It plays a crucial role in transmitting and receiving signals, allowing communication to occur wirelessly.

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  • 48. 

    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 Single Side Band (SSB) and Independent Side Bands (ISB) operating modes. SSB is a modulation technique where only one sideband is transmitted, resulting in more efficient use of bandwidth. ISB is a technique where multiple sidebands are transmitted independently, allowing for simultaneous transmission of different signals. These operating modes are commonly used in HF communications to maximize efficiency and optimize signal transmission.

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  • 49. 

    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
    A waveguide is a type of transmission line that is used when the frequencies are so high that their wavelength is minuscule. This is because at high frequencies, traditional transmission lines like coaxial cables become inefficient and cause significant signal loss. Waveguides, on the other hand, can effectively transmit these high-frequency signals with minimal loss. The design of waveguides allows them to confine and guide the electromagnetic waves within a narrow channel, ensuring efficient transmission at high frequencies. Therefore, using a waveguide becomes necessary when dealing with high-frequency signals where the wavelength is very small.

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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
  • Dec 12, 2017
    Quiz Created by
    Edward Kim
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