Set 2 Vol 2 Communication
Questions and Answers
- 1.
In a basic communication system, this is used to convert radio frequency (RF) current oscillation into electric and magnetic fields of force
- A.
Antenna
- B.
Transmitter
- C.
Coupler
- D.
Transmission lines
Correct Answer
A. AntennaExplanation
The correct answer is antenna. In a basic communication system, an antenna is used to convert radio frequency (RF) current oscillation into electric and magnetic fields of force. The antenna is responsible for transmitting and receiving electromagnetic waves, allowing for the communication between devices. It plays a crucial role in wireless communication systems by converting electrical signals into radio waves that can be transmitted through the air and received by other devices.Rate this question:
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- 2.
The concept where alternating current (AC) changes in magnitude, and reverses its direction during each cycle, is
- A.
An unproven hypothesis
- B.
The definition of propagation
- C.
What makes radio transmission possible
- D.
What led to the discovery of direct current (DC)
Correct Answer
C. What makes radio transmission possibleExplanation
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 carry information through the variation of their frequency and amplitude. AC current, with its changing magnitude and direction, can be used to generate and modulate radio waves, allowing for the transmission of audio, video, and data signals wirelessly.Rate this question:
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- 3.
At which point do magnetic fields around a wire no longer have time to collapse completely between alternations?
- A.
60 cycles per second (cps)
- B.
120 cps
- C.
10,000 cps
- D.
15,000 cps
Correct Answer
C. 10,000 cpsExplanation
At 10,000 cycles per second (cps), the magnetic fields around a wire do not have enough time to collapse completely between alternations. This is because at higher frequencies, the time available for the magnetic fields to collapse decreases, resulting in incomplete collapse. As a result, the magnetic fields around the wire are not able to fully collapse at 10,000 cps.Rate this question:
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- 4.
In radio-wave creation, which type of field detaches from the antenna and travels through space at great distances?
- A.
Radiation.
- B.
Induction
- C.
Gravitational
- D.
Electromotive
Correct Answer
A. Radiation.Explanation
Radio-wave creation involves the generation of electromagnetic waves that detach from the antenna and propagate through space at great distances. This process is known as radiation. Electromagnetic radiation, including radio waves, is characterized by the oscillation of electric and magnetic fields perpendicular to each other and the direction of propagation. These waves can travel through space without the need for a physical medium, making them ideal for long-distance communication. Induction refers to the transfer of energy between conductors through electromagnetic fields, while gravitational and electromotive fields are not directly related to the creation and propagation of radio waves.Rate this question:
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- 5.
Which types of polarization do most satellite communication terminals transmit and receive?
- A.
Transmit horizontal and receive vertical polarizations
- B.
Transmit vertical and receive horizontal polarizations
- C.
Transmit right-hand circular and receive left-hand circular polarizations
- D.
Transmit left-hand circular and receive right-hand circular polarizations
Correct Answer
C. Transmit right-hand circular and receive left-hand circular polarizationsExplanation
Most satellite communication terminals transmit right-hand circular polarizations and receive left-hand circular polarizations. This is because circular polarization helps to mitigate the effects of signal fading caused by changes in the orientation of the satellite and the terminal. By transmitting and receiving circular polarizations in opposite directions, the system can achieve better signal reception and minimize interference.Rate this question:
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- 6.
A resonant antenna effectively radiates a radio signal for frequencies close to its designed frequency. Which percentage range, plus or minus, is it usually within?
- A.
1
- B.
2
- C.
3
- D.
4
Correct Answer
B. 2Explanation
A resonant antenna is designed to efficiently radiate radio signals at a specific frequency. It operates within a certain bandwidth, typically within a range of frequencies close to its designed frequency. This range is usually within a percentage range of plus or minus 2%, meaning that the antenna can effectively radiate signals for frequencies that are 2% higher or lower than its designed frequency.Rate this question:
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- 7.
The design frequency of a resonant antenna is 10 megahertz (MHz). What will be its frequency range?
- A.
8–10 MHz
- B.
9–11 MHz
- C.
9.5–10.5 MHz
- D.
9.8–10.2 MHz
Correct Answer
D. 9.8–10.2 MHzExplanation
The frequency range of a resonant antenna is typically slightly above and below the design frequency. In this case, since the design frequency is 10 MHz, the frequency range would be 9.8–10.2 MHz. This allows for a small margin of error and ensures that the antenna can effectively resonate at the desired frequency.Rate this question:
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- 8.
The lowest frequency at which an antenna resonates is known as its
- A.
Standing wave
- B.
Fundamental
- C.
Resonation
- D.
Primary.
Correct Answer
B. FundamentalExplanation
The lowest frequency at which an antenna resonates is called its fundamental frequency. This is the frequency at which the antenna vibrates most easily and efficiently. It is the primary resonance frequency of the antenna and determines its basic operating characteristics.Rate this question:
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- 9.
The ability of an antenna to both receive and transmit equally well is known as the antenna’s
- A.
Bandwidth
- B.
Resonance
- C.
Reciprocity
- D.
Effectiveness
Correct Answer
C. ReciprocityExplanation
Reciprocity refers to the ability of an antenna to perform equally well in both receiving and transmitting signals. It means that the antenna's characteristics remain the same regardless of whether it is being used to transmit or receive signals. This property is crucial for efficient communication systems, as it allows for bidirectional signal transmission without the need for separate antennas for transmitting and receiving.Rate this question:
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- 10.
This matching device is inserted to make a transmitter “think” it is connected to a low standing-wave ratio (SWR) antenna
- A.
Stub
- B.
Balun
- C.
Coupler
- D.
Terminating resistor
Correct Answer
C. CouplerExplanation
A coupler is a device that is inserted to make a transmitter "think" it is connected to a low standing-wave ratio (SWR) antenna. A coupler is used to match the impedance of the transmitter to the impedance of the antenna, ensuring efficient power transfer and minimizing reflections. It allows the transmitter to operate at its maximum power output without damaging itself due to high SWR. A stub is a short length of transmission line used for impedance matching, a balun is a device that converts between balanced and unbalanced signals, and a terminating resistor is used to terminate a transmission line to prevent reflections.Rate this question:
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- 11.
This matching device would be used to connect a 52-ohms RG–213 cable to an antenna with an impedance of 600-ohms.
- A.
Balun.
- B.
Coupler
- C.
Reflector
- D.
Terminating resistor
Correct Answer
A. Balun.Explanation
A balun is a device used to match the impedance between two different transmission lines. 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 helps to ensure that there is minimal signal loss and maximum power transfer between the cable and the antenna.Rate this question:
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- 12.
Which type of antenna radiates radio energy equally well in all directions?
- A.
Omni-directional
- B.
Uni-directional
- C.
Bi-directional
- D.
Directional
Correct Answer
A. Omni-directionalExplanation
An omni-directional antenna radiates radio energy equally well in all directions. This type of antenna is designed to provide 360-degree coverage, making it suitable for applications where the signal needs to reach multiple locations or devices from a central point. Omni-directional antennas are commonly used in wireless communication systems, such as Wi-Fi networks, cellular networks, and broadcasting systems, to ensure a wide coverage area and uniform signal distribution. Unlike uni-directional, bi-directional, or directional antennas, omni-directional antennas do not require precise alignment or pointing towards a specific target, making them more convenient and versatile for general-purpose use.Rate this question:
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- 13.
Add this device to make a long-wire antenna more directional
- A.
Stub
- B.
Balun
- C.
Coupler
- D.
Terminating resistor
Correct Answer
D. Terminating resistorExplanation
A terminating resistor can be added to a long-wire antenna to make it more directional. When a long-wire antenna is not terminated properly, it can create reflections and standing waves, which can result in a loss of signal strength and a less directional pattern. By adding a terminating resistor at the end of the antenna, it absorbs the reflected energy and prevents it from interfering with the main signal, improving the antenna's directional characteristics.Rate this question:
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- 14.
Beam width of a directive antenna is measured at the
- A.
Quarter-power point
- B.
Half-power point
- C.
Three-quarters power point
- D.
Maximum value point
Correct Answer
B. Half-power pointExplanation
The beam width of a directive antenna is measured at the half-power point. This refers to the point at which the power of the antenna's radiation pattern is reduced to half of its maximum value. It is an important metric for determining the coverage area and directionality of the antenna. By measuring the beam width at the half-power point, we can understand the angular range over which the antenna radiates effectively.Rate this question:
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- 15.
A dipole or long-wire antenna is an example of a
- A.
Whip antenna
- B.
Hertz antenna
- C.
Marconi antenna
- D.
Vertical monopole
Correct Answer
B. Hertz antennaExplanation
A dipole or long-wire antenna is not an example of a Hertz antenna or Marconi antenna because those terms specifically refer to different types of antennas. A dipole or long-wire antenna is commonly known as a whip antenna, which is a type of vertical monopole antenna.Rate this question:
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- 16.
This is one of the simplest and most functional antennas in use
- A.
Quarter-wave vertical
- B.
Half-wave dipole
- C.
Inverted-V
- D.
GRA–4
Correct Answer
B. Half-wave dipoleExplanation
The half-wave dipole is considered one of the simplest and most functional antennas in use. It is a balanced antenna that consists of two equal-length conductive elements, each measuring half the wavelength of the desired frequency. The dipole antenna is widely used due to its efficiency and versatility in various applications, including radio and television broadcasting, wireless communication, and amateur radio. Its design allows for a broad frequency range and good radiation characteristics, making it a popular choice for many antenna systems.Rate this question:
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- 17.
The minimum length of a long-wire antenna is
- A.
One-quarter wavelength
- B.
One-half wavelength
- C.
One wavelength
- D.
Two wavelengths
Correct Answer
C. One wavelengthExplanation
The minimum length of a long-wire antenna is one wavelength because it needs to be long enough to effectively receive or transmit radio waves. A quarter wavelength or half wavelength would not be sufficient for proper resonance and efficient operation. A longer antenna allows for better reception and transmission of signals, which is why the minimum length is one wavelength.Rate this question:
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- 18.
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
- A.
Near-vertical incidence sky-wave
- B.
Helical
- C.
Inverted-V
- D.
Inverted-L
Correct Answer
A. Near-vertical incidence sky-waveExplanation
The near-vertical incidence sky-wave antenna is the correct choice for communicating over the horizon to an amphibious ship on the move or to 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 a near-vertical angle. It allows for long-range communication by utilizing the sky-wave propagation, which is ideal for reaching distant locations.Rate this question:
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- 19.
How are most antennas designed that are used in satellite communications?
- A.
Circular-directional
- B.
Omni-directional
- C.
Bi-directional
- D.
Directional
Correct Answer
D. DirectionalExplanation
Most antennas used in satellite communications are designed to be directional. This means that they are focused in a specific direction to transmit or receive signals. This design allows for better signal strength and reception in a specific area, making it more efficient for satellite communication. Circular-directional antennas are a subtype of directional antennas that can rotate and cover a wider range of directions. Omni-directional antennas, on the other hand, transmit and receive signals in all directions equally. Bi-directional antennas are designed to transmit and receive signals in two opposite directions.Rate this question:
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- 20.
Which type of polarization is used to radiate a signal using a helical satellite antenna?
- A.
Horizontal
- B.
Vertical
- C.
Circular
- D.
Linear
Correct Answer
C. CircularExplanation
Circular polarization is the type of polarization used to radiate a signal using a helical satellite antenna. Circular polarization refers to the rotation of the electric field of the electromagnetic wave in a circular pattern. This type of polarization allows the signal to be transmitted and received with minimal interference, even if the orientation of the receiving antenna is slightly misaligned. It is commonly used in satellite communication to ensure reliable transmission and reception of signals.Rate this question:
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- 21.
This type of antenna is used to transmit and receive microwave signals
- A.
Horn
- B.
Whip
- C.
Helical
- D.
Log-periodic
Correct Answer
A. HornExplanation
A horn antenna is used to transmit and receive microwave signals due to its wide bandwidth and high gain characteristics. It has a flared shape that allows for efficient transmission and reception of electromagnetic waves in the microwave frequency range. The horn antenna's design helps to focus and direct the signals, making it suitable for applications such as satellite communication, radar systems, and wireless networking. Unlike whip, helical, and log-periodic antennas, the horn antenna is specifically designed for microwave frequencies, making it the correct choice for this purpose.Rate this question:
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- 22.
Where are aircraft antennas normally housed?
- A.
Inside nonconductive radomes outside or flush with the fuselage
- B.
Inside conductive radomes outside or flush with the fuselage
- C.
Outside nonconductive radomes outside the fuselage
- D.
Inside conductive radomes flush with the fuselage
Correct Answer
A. Inside nonconductive radomes outside or flush with the fuselageExplanation
Aircraft antennas are normally housed inside nonconductive radomes, which are located outside or flush with the fuselage. Radomes are protective coverings made of nonconductive materials that allow radio signals to pass through while protecting the antenna from external elements. Placing the antennas inside radomes helps to minimize interference and ensure efficient communication between the aircraft and ground stations or other aircraft.Rate this question:
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- 23.
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?
- A.
90 and 180 degrees
- B.
60 and 90 degrees
- C.
30 and 60 degrees
- D.
5 and 30 degrees
Correct Answer
D. 5 and 30 degreesExplanation
Multi-hop, long-distance transmission in airborne antenna applications for frequencies in the upper portion of the high-frequency (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 and reach the desired destination. This technique allows for long-distance communication without the need for line-of-sight, making it suitable for airborne applications where the antenna may not always have a clear path to the target.Rate this question:
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- 24.
This is the best way to orient line-of-sight (LOS) antennas
- A.
Toward the true north bearing
- B.
Away from the receiving station
- C.
Away from the magnetic north bearing
- D.
In a straight path to the receiving station
Correct Answer
D. In a straight path to the receiving stationExplanation
The best way to orient line-of-sight (LOS) antennas is in a straight path to the receiving station. This ensures that there are no obstructions or obstacles that could interfere with the signal transmission. By aligning the antennas directly towards the receiving station, the signal can travel efficiently and effectively without any unnecessary deviation or loss of strength. This straight path orientation maximizes the signal strength and minimizes the chances of interference or signal degradation.Rate this question:
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- 25.
When siting a radio station, which type of foliage would have a more adverse effect on radio-wave propagation?
- A.
Broadleaf trees
- B.
Evergreen trees
- C.
Swamp grass
- D.
Sagebrush
Correct Answer
A. Broadleaf treesExplanation
Broadleaf trees would have a more adverse effect on radio-wave propagation. This is because their dense foliage and large leaves can absorb and scatter radio waves, causing signal loss and interference. Evergreen trees, on the other hand, have needle-like leaves that are less likely to obstruct radio waves. Swamp grass and sagebrush are not known to significantly impact radio-wave propagation.Rate this question:
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- 26.
This has the greatest effect on an antenna’s radiation pattern
- A.
Sun
- B.
Earth
- C.
Operator
- D.
Ionosphere
Correct Answer
B. EarthExplanation
The Earth has the greatest effect on an antenna's radiation pattern because the antenna's position and orientation relative to the Earth's surface can significantly impact its performance. The Earth's terrain, buildings, and other obstacles can cause reflections, diffraction, and multipath interference, which can distort the radiation pattern and affect the antenna's ability to transmit and receive signals effectively. Additionally, the Earth's magnetic field can also influence the radiation pattern, especially for antennas that are sensitive to polarization.Rate this question:
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- 27.
This is one fundamental rule about camouflage
- A.
Sawed-off branches and foliage should not be used
- B.
Site should be visualized from above
- C.
Equipment should be widely separated
- D.
Straight lines are obvious
Correct Answer
D. Straight lines are obviousExplanation
Straight lines are obvious when it comes to camouflage because they do not occur naturally in most environments. In nature, lines and shapes tend to be more curved and irregular. Straight lines can stand out and attract attention, making it easier for an observer to spot the camouflaged object. Therefore, it is important to avoid using straight lines in camouflage design to ensure better blending into the surroundings.Rate this question:
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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
- A.
Whip
- B.
Dipole
- C.
Discone
- D.
Near-vertical incidence sky-wave
Correct Answer
D. Near-vertical incidence sky-waveExplanation
The near-vertical incidence sky-wave is the most effective type of antenna in mountainous terrain with a mountain between you and the distant end. This type of antenna is designed to transmit and receive signals that are reflected off the ionosphere at a near-vertical angle. This allows the signals to bypass the mountain obstruction and reach the distant end. The near-vertical incidence sky-wave antenna is specifically designed for this purpose and is therefore the best choice in this scenario.Rate this question:
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- 29.
Which electronic warfare (EW) component responds to a tasking to search for, intercept, identify, and locate intentional and unintentional sources of radiated energy?
- A.
Attack
- B.
Control
- C.
Support
- D.
Protection
Correct Answer
C. SupportExplanation
The correct answer is "Support." In electronic warfare (EW), the support component is responsible for responding to a tasking to search for, intercept, identify, and locate intentional and unintentional sources of radiated energy. This component plays a crucial role in gathering information about the electromagnetic spectrum and providing intelligence to the other components.Rate this question:
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- 30.
Electromagnetic (EM) deception, as it applies to electronic warfare (EW), is
- A.
controlling the information an enemy receives
- B.
Eliminating some, or all, of an adversary’s electronic defenses
- C.
Conveying misleading information to an enemy through the deliberate radiation of EM energy
- D.
Degrading, or interfering with, the enemy’s use of the EM spectrum to limit an enemy’s combat capabilities
Correct Answer
C. Conveying misleading information to an enemy through the deliberate radiation of EM energyExplanation
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, which involves intentionally transmitting false or misleading signals to confuse or mislead the enemy. By radiating electromagnetic energy, the goal is to deceive the enemy and disrupt their ability to gather accurate information or effectively use their electronic defenses.Rate this question:
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