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

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 relevant to the establishment of HQ communications.

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About This Quiz
Z3D153 Volume 2 Ure - 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. This is the best way to orient line-of-sight (LOS) antennas.

Explanation

The best way to orient line-of-sight (LOS) antennas is by aligning them in a straight path to the receiving station. This ensures that the signal travels directly towards the intended destination without any obstacles or interference. Aligning the antennas towards the true north bearing or away from the receiving station or magnetic north bearing may result in signal degradation and poor communication quality. Therefore, the straight path to the receiving station is the most effective orientation for LOS antennas.

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

Explanation

Omni-directional antennas radiate radio energy equally well in all directions. Unlike uni-directional, bi-directional, or directional antennas, which focus the energy in a specific direction, omni-directional antennas are designed to provide a 360-degree coverage pattern. This makes them ideal for applications where the signal needs to reach multiple locations or devices from a central point without the need for precise aiming or alignment.

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

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

Explanation

Decryption refers to the process of converting encrypted information back into its original, intelligible form. It involves using a 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 an unreadable form to protect it from unauthorized access. Cryptography is the broader field that encompasses both encryption and decryption techniques. Cryptanalysis, on the other hand, refers to the study of cryptographic systems with the aim of breaking them and gaining unauthorized access to encrypted information.

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

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

Explanation

The Federal Communications Commission (FCC) is the US government agency responsible for dividing the radio frequency spectrum into different bands. They regulate and allocate different frequencies to various users, such as television and radio broadcasters, wireless communication providers, and other industries that rely on wireless technology. The FCC ensures that these bands are used efficiently and that interference is minimized, enabling effective communication and the smooth operation of wireless devices and services.

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

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

Explanation

Each word-of-day (WOD) is used with the HAVE QUICK II (HQII) communications multiple word-of-day (MWOD) for a duration of 24 hours. This means that the WOD is automatically changed every 24 hours without any manual intervention.

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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 

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. Radio waves that travel near the Earth's surface are called

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

Explanation

Reciprocity refers to the ability of an antenna to both receive and transmit signals equally well. This means that the antenna's characteristics remain the same regardless of whether it is used for receiving or transmitting. In other words, if an antenna is efficient in receiving signals, it will also be efficient in transmitting signals, and vice versa. This property is important in various communication systems where the same antenna is used for both sending and receiving signals.

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

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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14. This is one fundamental rule about camouflage.

Explanation

Straight lines are obvious because they do not occur naturally in nature. In a natural environment, objects and shapes tend to have more organic and irregular forms. Straight lines can stand out and attract attention, making them easily detectable by observers. Therefore, when using camouflage techniques, it is important to avoid straight lines to blend in with the surroundings effectively.

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

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 a weak signal from a mobile or portable radio and then retransmits it at a higher power, allowing the signal to reach further distances. By acting as a relay station, a repeater extends the range and coverage of communication for LMR devices, making it an ideal choice for maximizing distance between lower-powered equipment items.

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

Explanation

AFI 10–2501, Air Force Emergency Management Program, is the correct answer because it specifically outlines the requirements for communications squadrons to maintain installation notification and warning systems (INWS). This instruction provides guidance on emergency management procedures and responsibilities within the Air Force, including the maintenance and operation of INWS. It ensures that communications squadrons are equipped to effectively communicate and respond to emergency situations, thereby enhancing the overall emergency management capabilities of the Air Force.

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

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

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 and a higher water content, which can absorb and scatter radio waves more effectively. This absorption and scattering can result in a weaker signal and reduced coverage for the radio station. In contrast, evergreen trees, swamp grass, and sagebrush have less dense foliage and lower water content, allowing radio waves to pass through with less obstruction.

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

Explanation

OTAR stands for Over-The-Air Rekeying, which is a method used to change encryption keys over the radio channel in a two-way radio system. This process allows for secure and efficient key management, ensuring that the communication remains protected from unauthorized access. By regularly changing encryption keys, the system reduces the risk of key compromise and enhances the overall security of the communication.

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

Explanation

A single-site configuration is designed to provide coverage for a small geographical area. In this configuration, a single base station or repeater is used to cover the entire area, ensuring that users within the vicinity have reliable communication. This type of configuration is suitable for small businesses, campuses, or localized operations where a wide coverage area is not required. It allows for efficient use of resources and simplifies management since all communication devices operate on the same frequency and are connected to a single site.

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

Explanation

Having unbalanced channel loads is not a benefit of having a trunking network. Trunking networks are designed to efficiently allocate and manage resources, including channels, in order to optimize communication. Unbalanced channel loads can lead to congestion and inefficient use of resources. Therefore, it is not considered a benefit in a trunking network where the goal is to achieve better channel efficiency and equal distribution of traffic.

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22. In the giant-voice system, this controls the system's signal routing and power distribution.

Explanation

The control board is responsible for managing the signal routing and power distribution in the giant-voice system. It is the central component that oversees and regulates the flow of signals and power throughout the system. Without the control board, the system would not be able to properly route signals or distribute power to the necessary components. Therefore, the control board is crucial for the overall functioning and operation of the giant-voice system.

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

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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24. Which tactical data link (TDL) is a secure, full-duplex, point-to-point digital data link that uses satellite, microwave, or terrestrial cable, as opposed to a modulated waveform, to transmit data?

Explanation

Link 11b is a secure, full-duplex, point-to-point digital data link that uses satellite, microwave, or terrestrial cable to transmit data. It is different from other options like Link 4 and Link 16, which use modulated waveforms for data transmission.

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

Explanation

In high-frequency (HF) communications, the automatic link establishment (ALE) self-address refers to the address that the user has programmed for their station. This self-address is unique to each station and is used for communication purposes. It is not shared with other members or stations in the network.

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

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

Explanation

Circular polarization is used to radiate a signal using a helical satellite antenna. This type of polarization involves the rotation of the electric field of the signal in a circular motion. It is advantageous for satellite communication as it allows for better signal reception and transmission, regardless of the orientation of the receiving antenna. Circular polarization also helps to minimize signal interference and multipath effects, resulting in improved signal quality and reliability.

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

Explanation

The near-vertical incidence sky-wave antenna is the most effective type of antenna in mountainous terrain with a mountain between you and the distant end. This type of antenna is specifically designed to transmit and receive signals that are reflected off the ionosphere at a near-vertical angle. This allows the signals to bypass obstacles like mountains and reach the distant end effectively. The whip, dipole, and discone antennas are not specifically designed for mountainous terrain and may not perform as well in such conditions.

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

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

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

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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32. How many layers make up the Earth's atmosphere?

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

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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34. Where is the primary high frequency global communications system (HFGCS) network control station located?

Explanation

The primary high frequency global communications system (HFGCS) network control station is located at Andrews AFB, Maryland.

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

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

Explanation

The correct answer is conveying misleading information to an enemy through the deliberate radiation of EM energy. In electronic warfare, electromagnetic deception involves intentionally emitting electromagnetic energy to deceive the enemy by conveying false or misleading information. This can be done by mimicking friendly signals, creating false targets, or distorting enemy sensor readings. By manipulating the electromagnetic spectrum, the goal is to confuse and mislead the enemy, making it difficult for them to accurately assess the situation and make informed decisions.

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

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

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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39. Which frequency band is most susceptible to jamming?

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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40. On which regular ionospheric variation do sunspots occur?

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

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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42. In frequency-hopping (FH) operations, the interval at which each transmitter remains on a given frequency for a specific time is known as

Explanation

In frequency-hopping (FH) operations, the interval at which each transmitter remains on a given frequency for a specific time is known as dwell time. This refers to the duration that a transmitter stays on a particular frequency before hopping to the next frequency. It is an important parameter in FH systems as it determines the amount of time spent on each frequency and affects the system's performance in terms of interference, capacity, and reliability.

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43. Direct waves are radio waves that travel

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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44. The atmospheric recombination process is dependent on the

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

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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46. Which type of cryptographic algorithm permits the encryption key to be public?

Explanation

Asymmetric cryptographic algorithms allow the encryption key to be public. In this type of encryption, there are two different keys: a public key and a private key. The public key is used for encryption, and it can be freely shared with others. The private key, on the other hand, is kept secret and is used for decryption. This allows for secure communication between parties, as anyone can encrypt a message using the recipient's public key, but only the recipient with the corresponding private key can decrypt and read the message.

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47. Beam width of a directive antenna is measured at the

Explanation

The beam width of a directive antenna is the measure of the angle between the two points where the power of the antenna's radiation pattern is reduced to half of its maximum value. This is known as the half-power point. At this point, the antenna's radiation is spread over a wider angle, indicating a broader coverage area. Therefore, the correct answer is the half-power point.

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

Explanation

The half-wave dipole is a simple and efficient antenna design that is commonly used in various applications. It consists of two equal-length conductors, with the center connected to the signal source and the ends connected to ground. This antenna is called a half-wave dipole because its length is approximately half the wavelength of the radio waves it is designed to receive or transmit. The half-wave dipole has a balanced radiation pattern, meaning it radiates and receives signals equally well in all directions perpendicular to its axis. Its simplicity and functionality make it a popular choice for many communication systems.

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49. 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.

Explanation

The near-vertical incidence sky-wave antenna is the most suitable option for communicating over the horizon to an amphibious ship or a station up to 450 kilometers away. This type of antenna is specifically designed to transmit and receive signals that are reflected off the ionosphere at very steep angles, allowing for long-range communication. The helical, inverted-V, and inverted-L antennas are not optimized for this purpose and may not provide the same level of performance in long-distance communication.

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50. All statements concerning waveguides are true except

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

Explanation

A horn antenna is commonly used to transmit and receive microwave signals. Its design allows for efficient transmission and reception of these high-frequency signals. The shape of the horn antenna helps to focus and direct the microwave energy, making it an ideal choice for applications that require long-range communication or high-gain reception. The horn antenna's wide bandwidth also enables it to support a range of frequencies within the microwave spectrum. Therefore, the horn antenna is the most suitable option for transmitting and receiving microwave signals.

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52. Which frequency range will show little effect from precipitation?

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

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

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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55. Which type of hopping-rate category changes frequencies approximately 100 times per second?

Explanation

The medium hopping-rate category changes frequencies approximately 100 times per second. This means that the frequency at which it hops is faster than the slow category but slower than the fast category. The term "hopping-rate" refers to the frequency at which a device or system changes its operating frequency. Therefore, the medium hopping-rate category is the one that changes frequencies at a moderate speed, approximately 100 times per second.

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

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

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

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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59. 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?

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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60. What does the term "ICOM" indicate?

Explanation

The term "ICOM" indicates Integrated Communications Security. This term refers to a system or process that combines various communication methods and technologies to ensure the security and protection of sensitive information during transmission. It involves the integration of encryption, authentication, and other security measures to safeguard communications from unauthorized access or interception.

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61.  Leakage loss in a transmission line is minimized by using a

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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62. This is the correct statement concerning a wavelength.

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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63. This is the simplest form of an automatic link establishment (ALE) call.

Explanation

This is the simplest form of an automatic link establishment (ALE) call because it refers to a single communication between two individuals. ALE is a method used in radio communications to establish reliable connections between stations, and an individual call involves direct communication between two specific individuals rather than a group or any random person.

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64. A nonresonant transmission line is one with

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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65. Which secure communications device operates by simply sliding the key tape into the reader?

Explanation

The koi-18 is the correct answer because it is a secure communications device that operates by simply sliding the key tape into the reader.

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66. Which is not a major component of the giant-voice system?

Explanation

The giant-voice system is a warning system used to alert people in emergency situations. It typically consists of various components such as a siren cabinet, siren stack, decoder, and encoder. The decoder is responsible for receiving and interpreting the signals sent by the encoder, which contains the message or alert to be broadcasted. Therefore, the decoder is a major component of the giant-voice system.

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67. Which type of advanced waveform enables data and imagery situational awareness and provides enhanced combat effectiveness?

Explanation

Soldier radio enables data and imagery situational awareness and provides enhanced combat effectiveness. This means that soldier radio technology allows soldiers to have access to real-time information and visuals, which helps them make informed decisions and increases their effectiveness in combat situations.

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

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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69. The refractive index of air depends on moisture

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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70. In a land mobile radio (LMR) repeater system, a device that separates and isolates the incoming receive signal from the outgoing transmit signal and vice versa is known as a

Explanation

A duplexer is a device used in a land mobile radio (LMR) repeater system to separate and isolate the incoming receive signal from the outgoing transmit signal and vice versa. It allows the repeater to receive and transmit signals simultaneously without interference. By using filters and switches, the duplexer ensures that the transmit and receive signals are directed to the appropriate paths and prevents them from interfering with each other. Thus, a duplexer is the correct answer for this question.

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

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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72. Which multiple channel access method eliminates the requirement for a net control station (NCS) in the joint tactical information distribution system (JTIDS) by providing node-less communications network architecture?

Explanation

Time division is the multiple channel access method that eliminates the need for a net control station (NCS) in the joint tactical information distribution system (JTIDS) by providing node-less communications network architecture. In time division, each node is assigned a specific time slot to transmit data, allowing multiple nodes to share the same channel without the need for a central control station. This method ensures efficient and synchronized communication among the nodes without the requirement of a dedicated NCS.

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

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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74. Where are aircraft antennas normally housed?

Explanation

Aircraft antennas are typically housed inside nonconductive radomes that are located outside or flush with the fuselage. Radomes are protective covers made of nonconductive materials that allow radio signals to pass through while shielding the antennas from environmental factors. Placing the antennas inside radomes helps to maintain their performance and protect them from damage caused by weather conditions or aerodynamic forces.

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75. At which vertical angles should the multi-hop, long-distance transmission be used in airborne antenna applications for frequencies in the upper portion of the high-frequency (HF) band?

Explanation

Multi-hop, long-distance transmission in airborne antenna applications for frequencies in the upper portion of the HF band should be used at vertical angles of 5 and 30 degrees. This is because at these angles, the radio waves can be reflected off the ionosphere, allowing for longer-range communication. Vertical angles of 90 and 180 degrees would not be suitable as they would result in direct line-of-sight communication, which is not ideal for long-distance transmission. Similarly, angles of 60 and 90 degrees or 30 and 60 degrees would not provide the necessary reflection off the ionosphere for multi-hop transmission.

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76. When setting up a trunking network, users with common missions or functions are assigned as 

Explanation

In a trunking network, users with common missions or functions are assigned as talkgroups. Talkgroups are a way to group users together based on their specific roles or tasks within the network. This allows for efficient communication and coordination among users who need to collaborate or share information related to their common mission or function. By assigning users to specific talkgroups, they can easily communicate with each other without having to individually contact every user in the network.

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77. Which electronic warfare (EW) component responds to a tasking to search for, intercept, identify, and locate intentional and unintentional sources of radiated energy?

Explanation

The correct answer is "support." In electronic warfare, the support component is responsible for searching, intercepting, identifying, and locating intentional and unintentional sources of radiated energy. This component assists in gathering information about the electromagnetic spectrum to aid in decision-making and provide intelligence to other components.

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78. The ability of a receiver to reproduce the signal of a very weak station is characteristic of a receiver's

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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79. Add this device to make a long-wire antenna more directional.

Explanation

A terminating resistor can be added to a long-wire antenna to make it more directional. By placing a terminating resistor at the end of the wire, it absorbs any remaining energy that is not radiated, preventing it from reflecting back towards the antenna. This helps to reduce the amount of signal that is radiated in unwanted directions, enhancing the antenna's directivity and focusing the signal in the desired direction.

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80. The minimum length of a long-wire antenna is

Explanation

The minimum length of a long-wire antenna is one wavelength because it needs to be at least this long in order to effectively transmit and receive radio waves. A long-wire antenna works based on the principle of resonance, where the length of the antenna is matched to the wavelength of the signal it is designed to receive or transmit. This allows for maximum efficiency and effectiveness in signal transmission. Therefore, a long-wire antenna must be at least one wavelength long to function properly.

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

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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82. The Air Force integrates with modified close air support aircraft with digitized battlefield information using this type of network.

Explanation

The Air Force integrates with modified close air support aircraft with digitized battlefield information using the Situation Awareness Data Link (SADL). This network allows for the transmission of real-time situational awareness data between ground and airborne platforms. By utilizing SADL, the Air Force is able to enhance communication and coordination, providing pilots with critical information to effectively engage targets and support ground forces.

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83. The Earth's conductivity is determined by the type of

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

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

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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86. This matching device would be used to connect a 52-ohms RG–213 cable to an antenna with an impedance of 600-ohms.

Explanation

A balun is a device used to match the impedance of two different components in a circuit. In this case, the balun would be used to connect the 52-ohms RG-213 cable to the antenna with an impedance of 600-ohms. The balun would ensure that the impedance mismatch between the cable and the antenna is minimized, allowing for efficient signal transmission and reception.

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87. A dipole or long-wire antenna is an example of a

Explanation

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88. How are most antennas designed that are used in satellite communications?

Explanation

Most antennas used in satellite communications are designed to be directional. This means that they are specifically designed to focus their transmission and reception in a specific direction, allowing for a more focused and efficient communication with the satellite. This design helps to minimize interference and maximize the signal strength, making directional antennas ideal for long-distance satellite communications.

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89. This has the greatest effect on an antenna's radiation pattern.

Explanation

The earth has the greatest effect on an antenna's radiation pattern because the earth's surface acts as a reflecting medium for radio waves. The ground can either enhance or attenuate the signal depending on its composition and conductivity. The earth's surface also causes the radio waves to refract and diffract, resulting in changes to the antenna's radiation pattern. Additionally, the earth's curvature affects the line-of-sight propagation, causing the antenna's radiation pattern to be influenced by the distance and height above ground.

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

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

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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92. This provides the interface between dispatch consoles and the central controller in a typical trunking system.

Explanation

Switching equipment is the correct answer because it serves as the interface between dispatch consoles and the central controller in a typical trunking system. Switching equipment allows for the routing and switching of voice and data signals between different communication channels, ensuring efficient communication between dispatch consoles and the central controller. It plays a crucial role in establishing and maintaining connections in the trunking system, facilitating effective communication and coordination.

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93. This differentiates the enterprise land mobile radio (ELMR) network from a regular trunking or conventional network.

Explanation

A centralized core controller is what sets the enterprise land mobile radio (ELMR) network apart from a regular trunking or conventional network. It is responsible for managing and controlling the entire network, ensuring seamless communication between different devices and users. This centralized control allows for better coordination and efficiency in the network, making it more reliable and secure.

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

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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95. When discussing resonant and nonresonant transmission lines,

Explanation

not-available-via-ai

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96. This is not a major network within the Military Auxiliary Radio Service (MARS).

Explanation

UHF stands for Ultra High Frequency. It is a frequency band used for communication purposes. In the context of the Military Auxiliary Radio Service (MARS), UHF is not considered a major network. MARS is a civilian auxiliary of the United States Air Force that provides communication support to the military and other government agencies. While UHF may be utilized for certain communication purposes within MARS, it is not a primary or major network within the service.

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97. Which process permits communication in shadow regions behind obstacles?

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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98. This matching device is inserted to make a transmitter "think" it is connected to a low standing-wave ratio (SWR) antenna.

Explanation

A coupler is a device that is inserted to make a transmitter "think" it is connected to a low standing-wave ratio (SWR) antenna. This means that the coupler helps match the impedance of the transmitter to the impedance of the antenna, ensuring efficient transfer of power and minimizing reflections. By doing so, the coupler helps optimize the performance of the transmitter and ensures that it operates at its maximum potential.

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99. Which automatic link establishment (ALE) call option lets you call a predefined group of stations with a single shared address, and requires them to respond, one at a time, in a predefined order?

Explanation

The correct answer is "net." In automatic link establishment (ALE), a "net" refers to a predefined group of stations that share a single address. When initiating a call to a net, the stations within the group are required to respond one at a time, in a predetermined order. This allows for efficient and organized communication within the group.

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100. Which type of advanced waveform was designed to operate on manned, vehicular-based communication systems?

Explanation

Wideband networking is the correct answer because it is a type of advanced waveform that was specifically designed to operate on manned, vehicular-based communication systems. This waveform allows for high-speed data transmission and reliable communication between vehicles, making it suitable for military applications where reliable communication is crucial. The other options, soldier radio, mobile user objective system, and adaptive network wideband waveform, do not specifically mention being designed for manned, vehicular-based communication systems.

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This is the best way to orient line-of-sight (LOS) antennas.
Which type of antenna radiates radio energy equally well in all...
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The process of unscrambling encrypted information so that it is...
A combination transmitter and receiver, built as a single unit and...
Which US government agency divides the radio frequency spectrum into...
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A transmission line that consists of a center conductor, placed inside...
Radio waves that travel near the Earth's surface are called
The ability of an antenna to both receive and transmit equally well is...
In sky-wave propagation, frequencies higher than the critical...
This is one fundamental rule about camouflage.
Which type of conventional land mobile radio (LMR) device maximizes...
Which Air Force instruction (AFI) requires communications squadrons to...
The design frequency of a resonant antenna is 10 megahertz (MHz). What...
When siting a radio station, which type of foliage would have a more...
The common name for the method of changing encryption keys over the...
Which type of site configuration was designed to provide coverage for...
Which statement is not a benefit of having a trunking network?
In the giant-voice system, this controls the system's signal routing...
In radio-wave creation, which type of field detaches from the antenna...
Which tactical data link (TDL) is a secure, full-duplex,...
In high-frequency (HF) communications, your station's automatic link...
In sky- and ground-wave propagation, the area of silence where no...
Which type of polarization is used to radiate a signal using a helical...
This is the most effective type of antennas in mountainous terrain...
During which season do we have the wider range of critical frequencies...
As ionospheric solar variations, sunspots are disturbances that appear...
The angle at which a radio wave enters the ionosphere is known as the
How many layers make up the Earth's atmosphere?
This will likely result if a transmission line is terminated in an...
Where is the primary high frequency global communications system...
The concept where alternating current (AC) changes in magnitude, and...
Electromagnetic (EM) deception, as it applies to electronic warfare...
A waveguide is a type of transmission line that you would use 
High-frequency (HF) transmissions are normally conducted in which two...
Which frequency band is most susceptible to jamming?
On which regular ionospheric variation do sunspots occur?
The ability of a receiver to reproduce the input signal accurately is...
In frequency-hopping (FH) operations, the interval at which each...
Direct waves are radio waves that travel
The atmospheric recombination process is dependent on the
Which layer of the ionosphere is most important for high-frequency...
Which type of cryptographic algorithm permits the encryption key to be...
Beam width of a directive antenna is measured at the
This is one of the simplest and most functional antennas in use
You should use this type of antenna to communicate over the horizon to...
All statements concerning waveguides are true except
This type of antenna is used to transmit and receive microwave signals
Which frequency range will show little effect from precipitation?
 Line-of-sight (LOS) radio waves that are guided through the air...
Conductor material resistance in a transmission line leads to this...
Which type of hopping-rate category changes frequencies approximately...
 In a basic communication system, this is used to convert radio...
At which point do magnetic fields around a wire no longer have time to...
Which types of polarization do most satellite communication terminals...
A resonant antenna effectively radiates a radio signal for frequencies...
What does the term "ICOM" indicate?
 Leakage loss in a transmission line is minimized by using a
This is the correct statement concerning a wavelength.
This is the simplest form of an automatic link establishment (ALE)...
A nonresonant transmission line is one with
Which secure communications device operates by simply sliding the key...
Which is not a major component of the giant-voice system?
Which type of advanced waveform enables data and imagery situational...
The term frequency of optimum transmission (FOT) is also referred to...
The refractive index of air depends on moisture
In a land mobile radio (LMR) repeater system, a device that separates...
The lowest frequency at which an antenna resonates is known as its
Which multiple channel access method eliminates the requirement for a...
Determine the wavelength of a 250 megahertz (MHz) signal.
Where are aircraft antennas normally housed?
At which vertical angles should the multi-hop, long-distance...
When setting up a trunking network, users with common missions or...
Which electronic warfare (EW) component responds to a tasking to...
The ability of a receiver to reproduce the signal of a very weak...
Add this device to make a long-wire antenna more directional.
The minimum length of a long-wire antenna is
There are several critical sky-wave propagation angles and...
The Air Force integrates with modified close air support aircraft with...
The Earth's conductivity is determined by the type of
When comparing the radio and optical horizons, which one is farther...
Which condition gives sky-wave propagation its ability to communicate...
This matching device would be used to connect a 52-ohms RG–213...
A dipole or long-wire antenna is an example of a
How are most antennas designed that are used in satellite...
This has the greatest effect on an antenna's radiation pattern.
Which two transmission line properties determine its characteristic...
This term is used to describe radio waves that bend as they travel...
This provides the interface between dispatch consoles and the central...
This differentiates the enterprise land mobile radio (ELMR) network...
The amount of skin-effect loss is directly proportional to the
When discussing resonant and nonresonant transmission lines,
This is not a major network within the Military Auxiliary Radio...
Which process permits communication in shadow regions behind...
This matching device is inserted to make a transmitter "think" it is...
Which automatic link establishment (ALE) call option lets you call a...
Which type of advanced waveform was designed to operate on manned,...
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