3D153 Vol 2 Ure
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Questions and Answers
- 1.
(201) Equipment used for generating, amplifying, and transmitting RF carrier is collectively called
- A.
A receiver.
- B.
An antenna
- C.
A transmitter
- D.
A transmission line
Correct Answer
C. A transmitterExplanation
The equipment used for generating, amplifying, and transmitting RF carrier is collectively called a transmitter. This is because a transmitter is responsible for generating and amplifying the radio frequency signal before transmitting it through an antenna. The receiver, on the other hand, is used for receiving and demodulating the signal. The transmission line is used to transfer the signal from the transmitter to the antenna. Therefore, the correct answer is a transmitter.Rate this question:
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- 2.
(201) What basic receiver function involves having the transmitted electromagnetic wave passthrough the receive antenna in such a manner as to induce a voltage in the antenna?
- A.
Reproduction
- B.
Reception
- C.
Detection
- D.
Selection
Correct Answer
B. ReceptionExplanation
Reception is the correct answer because it involves the process of having the transmitted electromagnetic wave pass through the receive antenna and inducing a voltage in the antenna. This is the fundamental function of a receiver, where it captures and converts the electromagnetic signals into usable electrical signals for further processing. The other options, reproduction, detection, and selection, do not accurately describe this specific process of inducing a voltage in the receive antenna.Rate this question:
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- 3.
(201) The ability of a receiver to reproduce the signal of a very weak station is the characteristic ofthe receiver’s
- A.
Fidelity
- B.
Capacity
- C.
Sensitivity
- D.
Selectivity
Correct Answer
C. SensitivityExplanation
Sensitivity refers to the ability of a receiver to reproduce the signal of a very weak station. A receiver with high sensitivity can pick up and amplify weak signals, allowing the user to receive stations that may be far away or have a low power output. Fidelity refers to the accuracy with which the receiver reproduces the original signal, capacity refers to the amount of information the receiver can handle, and selectivity refers to the ability of the receiver to separate and filter out unwanted signals.Rate this question:
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- 4.
(201) The ability to reproduce the input signal accurately is the characteristics of the receiver’s
- A.
Fidelity
- B.
Capacity
- C.
Sensitivity
- D.
Fidelity
Correct Answer
A. FidelityExplanation
The ability to reproduce the input signal accurately is known as fidelity. Fidelity refers to the accuracy and faithfulness with which a receiver can reproduce the original signal without any distortion or loss of information. It is an important characteristic of a receiver as it ensures that the received signal is as close to the original as possible, allowing for clear and accurate communication.Rate this question:
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- 5.
(202) Which of the following CANNOT be performed by the transceiver’s computerizedcomponents and micro-circuitry?
- A.
Specific equipment faults.
- B.
Internal equipment tests
- C.
Internal calibrations
- D.
Repair itself
Correct Answer
D. Repair itselfExplanation
The transceiver's computerized components and micro-circuitry are responsible for various functions such as specific equipment faults, internal equipment tests, and internal calibrations. However, the transceiver's computerized components and micro-circuitry cannot repair itself.Rate this question:
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- 6.
(203) Resistance of the conductor material in a transmission line leads to which type of loss?
- A.
Copper
- B.
Radiation
- C.
Inductive
- D.
Skin-effect
Correct Answer
A. CopperExplanation
The resistance of the conductor material in a transmission line leads to copper loss. As current flows through the conductor, it encounters resistance, which results in the conversion of electrical energy into heat. This heat generation causes power loss in the form of copper loss. Copper loss is a common type of power loss in transmission lines and is influenced by factors such as the length and cross-sectional area of the conductor.Rate this question:
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- 7.
(203) Leakage loss in a transmission line can be minimized by using a
- A.
Thinner conductor
- B.
Thicker conductor
- C.
Very low-resistance dielectric
- D.
Very high-resistance dielectric
Correct Answer
D. Very high-resistance dielectricExplanation
Using a very high-resistance dielectric can minimize leakage loss in a transmission line. Leakage loss refers to the energy that is lost as heat due to the leakage of electric current from the conductor to the surrounding environment. By using a high-resistance dielectric, the amount of current leakage is reduced, resulting in lower energy loss. This is because the high-resistance dielectric acts as an insulator, preventing the flow of current through it and minimizing the leakage.Rate this question:
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- 8.
(203) A transmission line that consists of a center conductor placed inside a rigid metal tubefunctioning as the outer tube is called a
- A.
Flexible coaxial cable.
- B.
Rigid coaxial cable.
- C.
Waveguide
- D.
Twin lead
Correct Answer
B. Rigid coaxial cable.Explanation
A transmission line that consists of a center conductor placed inside a rigid metal tube functioning as the outer tube is called a rigid coaxial cable. This type of coaxial cable provides better protection against interference and signal loss due to its rigid structure. The outer metal tube acts as a shield, preventing external electromagnetic interference from affecting the signal transmission. The rigid coaxial cable is commonly used in applications that require high-frequency signal transmission, such as telecommunications and broadcasting.Rate this question:
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- 9.
(203) Which statement concerning waveguides is FALSE?
- A.
Very slight damage to the external surface of a waveguide can cause arcing.
- B.
Their conductive material construction is easily dented.
- C.
Effectiveness of waveguides is hindered by moisture.
- D.
Waveguides can be destroyed by corrosion.
Correct Answer
A. Very slight damage to the external surface of a waveguide can cause arcing.Explanation
Waveguides are designed to handle high power levels, and therefore very slight damage to the external surface of a waveguide is unlikely to cause arcing. Arcing is more likely to occur when there is significant damage or a large discontinuity in the waveguide structure.Rate this question:
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- 10.
(203) What two properties of a transmission line determine its characteristic impedance?
- A.
Inductance and resistance.
- B.
Inductance and capacitance.
- C.
Resistance and capacitance.
- D.
Length and type of shielding.
Correct Answer
B. Inductance and capacitance.Explanation
The characteristic impedance of a transmission line is determined by the inductance and capacitance of the line. Inductance is the property that opposes changes in current, while capacitance is the property that opposes changes in voltage. These two properties work together to determine the impedance, or resistance to the flow of electrical energy, in the transmission line. The inductance and capacitance values are dependent on the physical characteristics of the line, such as its length and the type of insulation or dielectric material used.Rate this question:
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- 11.
(203) Using figure 1–10, determine the electrical length if the frequency is changed from 150MHz to 250 MHz.
- A.
8.33 meters
- B.
8.33 wavelengths
- C.
83.3 meters
- D.
83.3 wavelengths
Correct Answer
B. 8.33 wavelengthsExplanation
The electrical length of a transmission line is determined by the number of wavelengths it takes for a signal to travel through it. In this question, the frequency is changed from 150MHz to 250MHz. Since frequency and wavelength are inversely proportional, as the frequency increases, the wavelength decreases. Therefore, the electrical length will be the same as the original length, but measured in terms of the new wavelength. So, the correct answer is 8.33 wavelengths.Rate this question:
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- 12.
(203) Which statement concerning line lengths is TRUE?
- A.
Frequency and electrical length are inversely proportional.
- B.
Frequency and physical length are directly proportional.
- C.
With constant physical length, frequency and electrical length are directly related.
- D.
With constant physical length, frequency and electrical length are inversely related.
Correct Answer
C. With constant physical length, frequency and electrical length are directly related.Explanation
This statement is true because frequency and electrical length are directly related when the physical length is constant. This means that as the frequency increases, the electrical length also increases, and vice versa. This relationship is important in understanding the behavior of electromagnetic waves and designing various electronic systems.Rate this question:
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- 13.
(203) A nonresonant transmission line is a line
- A.
Having reflected waves.
- B.
Having no reflected waves.
- C.
With maximum voltage across its open termination.
- D.
With maximum voltage across its shorted termination.
Correct Answer
B. Having no reflected waves.Explanation
A nonresonant transmission line is a line that does not have any reflected waves. This means that all of the energy that is sent down the line is absorbed by the load at the end of the line, and there is no energy bouncing back towards the source. This is desirable in many applications as it allows for efficient transmission of signals without any loss or distortion caused by reflected waves.Rate this question:
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- 14.
(203) If a transmission line is terminated in an open, what will likely result?
- A.
Signal loss would be negligible.
- B.
There would be significant signal loss.
- C.
Current would be at maximum at the termination.
- D.
Voltage would be at minimum at the termination.
Correct Answer
B. There would be significant signal loss.Explanation
When a transmission line is terminated in an open, there will be a mismatch between the impedance of the line and the termination impedance. This mismatch will cause a portion of the signal to be reflected back towards the source, resulting in signal loss. Therefore, there would be significant signal loss in this scenario.Rate this question:
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- 15.
(204) The concept that alternating current changes in magnitude and reverses its direction duringeach 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.
Correct Answer
C. What makes radio transmission possible.Explanation
The concept that alternating current changes in magnitude and reverses its direction during each cycle is what makes radio transmission possible. Radio waves are generated by rapidly changing the direction and magnitude of the electric current, which creates oscillating electromagnetic fields. These oscillating fields can then be detected by antennas and converted back into electrical signals, allowing for the transmission and reception of radio signals. Therefore, the concept of alternating current is essential for the functioning of radio transmission.Rate this question:
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- 16.
(204) At what point do magnetic fields around a wire no longer have time to collapse completelybetween alternations?
- A.
60 cycles per second (cps).
- B.
120 cps
- C.
10,000 cps
- D.
15,000 cps
Correct Answer
C. 10,000 cpsExplanation
The correct answer is 10,000 cps. At this frequency, the alternations of the magnetic fields around a wire are occurring so rapidly that there is not enough time for the fields to collapse completely between each alternation. This means that the magnetic fields remain relatively constant and do not have enough time to fully collapse before they are reestablished in the opposite direction.Rate this question:
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- 17.
(204) Which basic field detaches from the antenna and travels through space at great distances?
- A.
Radiation
- B.
Induction
- C.
Gravitational
- D.
Electromotive
Correct Answer
A. RadiationExplanation
Radiation is the correct answer because it refers to the process by which energy is emitted in the form of waves or particles and travels through space. In the context of the question, radiation specifically refers to electromagnetic radiation, such as radio waves, which detach from the antenna and travel through space over great distances.Rate this question:
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- 18.
(204) Areas in which no antenna radiation pattern passes through are called
- A.
Nulls
- B.
Lobes
- C.
Free space
- D.
Nonresonant
Correct Answer
A. NullsExplanation
Nulls are areas in which no antenna radiation pattern passes through. These are regions where the signal strength is significantly weakened or completely absent. Antennas are designed to radiate electromagnetic waves in specific directions, and nulls occur when the waves cancel each other out or when obstacles block the signal. Nulls can be problematic in communication systems as they can lead to signal dropouts and reduced coverage.Rate this question:
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- 19.
(205) If the electric field component travels in a plane perpendicular to the Earth’s surface, theradio wave is considered to be polarized
- A.
Magnetically
- B.
Horizontally.
- C.
Circularly.
- D.
Vertically
Correct Answer
D. VerticallyExplanation
If the electric field component of a radio wave travels in a plane perpendicular to the Earth's surface, the wave is considered to be vertically polarized. This means that the electric field oscillates in a vertical direction as the wave propagates.Rate this question:
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- 20.
(206) The actual range of frequencies within the antenna’s bandwidth is called the
- A.
Wavelength
- B.
Operating zone
- C.
Frequency range
- D.
Bandwidth range
Correct Answer
C. Frequency rangeExplanation
The actual range of frequencies within the antenna's bandwidth is referred to as the frequency range. This term encompasses the specific frequencies that the antenna is capable of transmitting or receiving signals at. It indicates the span of frequencies that the antenna is designed to operate within, allowing for effective communication within that range. The frequency range is an important consideration when selecting an antenna for a particular application, as it determines the compatibility and performance of the antenna with the desired frequency band.Rate this question:
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- 21.
(206) What measurement is used to determine whether an antenna is resonant at a particularfrequency?
- A.
Distortion.
- B.
Standing wave ratio.
- C.
Signal-to-noise ratio.
- D.
Percent of modulation.
Correct Answer
B. Standing wave ratio.Explanation
The standing wave ratio is used to determine whether an antenna is resonant at a particular frequency. The standing wave ratio measures the amount of power that is being reflected back from the antenna compared to the amount of power being delivered to the antenna. A lower standing wave ratio indicates that the antenna is resonant and efficiently transmitting power, while a higher standing wave ratio indicates that there is a mismatch between the antenna and the transmission line. Distortion, signal-to-noise ratio, and percent of modulation are not measurements used to determine the resonance of an antenna.Rate this question:
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- 22.
(206) The standard used to measure the radiating effectiveness (gain) of an antenna system is the
- A.
Marconi antenna.
- B.
Isotropic antenna.
- C.
Hertz antenna.
- D.
Whip antenna.
Correct Answer
B. Isotropic antenna.Explanation
The correct answer is isotropic antenna. An isotropic antenna is a theoretical antenna that radiates equally in all directions, with a gain of 0 decibels (dBi). It serves as a reference point for comparing the gain of other antennas. When the gain of an actual antenna is measured, it is compared to the isotropic antenna to determine its radiating effectiveness. The Marconi antenna, Hertz antenna, and whip antenna are specific types of antennas and not used as a standard for measuring antenna gain.Rate this question:
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- 23.
(206) What does the overall effectiveness of an entire transmitting and receiving system dependlargely upon?
- A.
Impedance matching.
- B.
Antenna distance.
- C.
Antenna properties.
- D.
Line characteristics.
Correct Answer
A. Impedance matching.Explanation
The overall effectiveness of an entire transmitting and receiving system largely depends on impedance matching. Impedance matching ensures that the impedance of the source (transmitter) and the load (antenna) are matched, allowing for maximum power transfer and minimizing signal reflections. Antenna distance, antenna properties, and line characteristics can also impact the system's performance, but impedance matching is the most crucial factor for optimal functioning.Rate this question:
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- 24.
(206) The ability of an antenna to both receive and transmit equally well is known as theantenna’s
- A.
Bandwidth.
- B.
Resonance.
- C.
Reciprocity.
- D.
Effectiveness.
Correct Answer
C. Reciprocity.Explanation
Reciprocity refers to the ability of an antenna to perform equally well in both receiving and transmitting signals. It implies that the antenna's characteristics, such as gain and radiation pattern, remain the same regardless of whether it is used for receiving or transmitting. Bandwidth refers to the range of frequencies over which an antenna can operate effectively, resonance refers to the natural frequency at which an antenna vibrates, and effectiveness is a general term that does not specifically describe the ability to receive and transmit signals equally well.Rate this question:
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- 25.
(207) Which antenna radiates radio energy equally well in all directions?
- A.
Omni-directional.
- B.
Uni-directional.
- C.
Bi-directional.
- D.
Directional.
Correct Answer
A. Omni-directional.Explanation
An omni-directional antenna radiates radio energy equally well in all directions. This means that it can transmit and receive signals from any direction without the need for adjusting or orienting the antenna. This type of antenna is commonly used in applications where a wide coverage area is needed, such as in broadcasting or wireless communication systems. Uni-directional, bi-directional, and directional antennas, on the other hand, have specific patterns or angles in which they transmit or receive signals, making them more suitable for targeted or specific communication purposes.Rate this question:
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- 26.
(207) Which antenna type is usually used on long-range, point-to-point communication where theconcentrated radio energy is needed for circuit reliability?
- A.
Omni-directional.
- B.
Uni-directional.
- C.
Bi-directional.
- D.
Circular.
Correct Answer
B. Uni-directional.Explanation
Uni-directional antennas are usually used on long-range, point-to-point communication where concentrated radio energy is needed for circuit reliability. These antennas focus the radio energy in one direction, allowing for a stronger and more reliable signal over long distances. Omni-directional antennas radiate the signal in all directions, making them less suitable for long-range point-to-point communication. Bi-directional antennas transmit and receive signals in two opposite directions, while circular antennas are designed to radiate the signal in a circular pattern, which may not be ideal for long-range point-to-point communication.Rate this question:
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- 27.
(208) Ungrounded lengths of wire specifically designed to be either a half-wavelength or morethan full wavelength long is called a
- A.
Reflector.
- B.
Hertz antenna
- C.
Marconi antenna.
- D.
Vertical monopole.
Correct Answer
B. Hertz antennaExplanation
A Hertz antenna refers to ungrounded lengths of wire that are designed to be either a half-wavelength or more than a full wavelength long. This type of antenna is used for transmitting and receiving radio waves and is named after Heinrich Hertz, a German physicist who first demonstrated the existence of electromagnetic waves. The Hertz antenna is commonly used in wireless communication systems and is known for its efficiency in transmitting and receiving signals.Rate this question:
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- 28.
(208) 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 antenna. -
- 29.
(209) What type of directivity does the whip antenna provide?
- A.
Bidirectional.
- B.
Unidirectional.
- C.
Omni-directional.
- D.
Near vertical directional.
Correct Answer
C. Omni-directional.Explanation
The whip antenna provides omni-directional directivity, meaning it radiates and receives signals equally in all directions. This makes it suitable for applications where signals need to be transmitted and received from multiple directions without the need for precise aiming or alignment.Rate this question:
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- 30.
(209) What is probably the worst antenna that can be used on sky-wave circuits?
- A.
Whip.
- B.
Dipole.
- C.
Rhombic.
- D.
Discone.
Correct Answer
A. Whip.Explanation
A whip antenna is probably the worst antenna that can be used on sky-wave circuits because it is very short and lacks the necessary length to efficiently transmit and receive signals at high frequencies. This results in poor signal strength and limited range, making it less effective for long-distance communication via sky-wave propagation. Dipole, rhombic, and discone antennas are all better options for sky-wave circuits as they are designed to have the appropriate length and characteristics for optimal performance in this type of communication.Rate this question:
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- 31.
(209) What antenna radiates or receives on many of its particular elements?
- A.
Whip.
- B.
Dipole.
- C.
Discone.
- D.
Log-periodic.
Correct Answer
D. Log-periodic.Explanation
A log-periodic antenna is designed to radiate or receive on many of its particular elements. Unlike other types of antennas like whip, dipole, and discone, a log-periodic antenna has a wide frequency range and can operate on multiple frequencies simultaneously. This makes it suitable for applications where a broad range of frequencies needs to be covered, such as in communication systems or radio broadcasting.Rate this question:
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- 32.
(209) What 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 dipole.Explanation
A half-wave dipole is one of the simplest and most functional antennas in use. It consists of two conductive elements, each measuring half the wavelength of the signal being transmitted or received. The dipole antenna is easy to construct and provides a balanced radiation pattern, making it effective for both transmitting and receiving signals. It is commonly used in radio communication and is known for its efficiency and versatility.Rate this question:
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- 33.
(209) What is the minimum length for a long-wire antenna?
- A.
One-quarter wavelength.
- B.
One-half wavelength.
- C.
One wavelength.
- D.
Two wavelengths.
Correct Answer
B. One-half wavelength.Explanation
A long-wire antenna is a type of antenna that is used for transmitting and receiving radio signals. The length of the antenna is crucial for its performance. The minimum length for a long-wire antenna is one-half wavelength. This length allows for the antenna to efficiently radiate and receive signals. A shorter antenna would not be able to effectively capture and transmit the radio waves, while a longer antenna would introduce unnecessary complexity and could lead to interference. Therefore, a one-half wavelength is the optimal length for a long-wire antenna.Rate this question:
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- 34.
(209) A long-wire’s takeoff angle depends on the antenna’s
- A.
Length.
- B.
Directivity.
- C.
Front-to-back ratio.
- D.
Standing wave ratio.
Correct Answer
A. Length.Explanation
The takeoff angle of a long wire antenna is determined by its length. The longer the wire, the lower the takeoff angle. This is because longer wires have a higher radiation resistance and are more efficient at radiating energy at lower angles. Therefore, the length of the antenna directly affects the angle at which the signal is transmitted.Rate this question:
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- 35.
(209) A common satellite antenna is the
- A.
Whip.
- B.
Discone.
- C.
Parabolic.
- D.
Long-wire.
Correct Answer
C. Parabolic.Explanation
A parabolic satellite antenna is a common type of satellite antenna that is shaped like a parabola. The shape of the parabolic dish allows it to focus incoming radio waves onto a receiver, improving the signal strength and quality. This design is commonly used for satellite communication because it provides high gain and can effectively transmit and receive signals over long distances. The other options, such as whip, discone, and long-wire, are not typically used as satellite antennas.Rate this question:
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- 36.
(209) A helical satellite antenna radiates a signal with what type of polarization?
- A.
Horizontal.
- B.
Vertical.
- C.
Circular.
- D.
Linear.
Correct Answer
C. Circular.Explanation
A helical satellite antenna radiates a signal with circular polarization because the helical design of the antenna causes the electromagnetic waves to rotate as they are emitted. This means that the electric field vector of the signal rotates in a circular motion as it propagates, resulting in circular polarization. Circular polarization is advantageous for satellite communication as it helps to mitigate signal degradation caused by changes in the orientation of the receiving antenna.Rate this question:
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- 37.
(210) Which type of airborne antenna can be designed into any part of an aerospace vehicle’ssurface, so that it does not upset its aerodynamic properties?
- A.
Fixed blade.
- B.
Conformal.
- C.
Probe tip.
- D.
Whip.
Correct Answer
B. Conformal.Explanation
A conformal antenna is designed to be integrated seamlessly into the surface of an aerospace vehicle without affecting its aerodynamic properties. This means that the antenna can be shaped and positioned in a way that it blends in with the vehicle's structure, minimizing any disruption to its airflow. This type of antenna is ideal for applications where maintaining the vehicle's aerodynamic performance is crucial, such as in aircraft or missiles.Rate this question:
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- 38.
(211) In selecting an antenna for a circuit, what is the first thing to consider?
- A.
Type of propagation.
- B.
Type of antenna.
- C.
Distance of the communication.
- D.
Operating frequency of the antenna.
Correct Answer
A. Type of propagation.Explanation
The first thing to consider when selecting an antenna for a circuit is the type of propagation. Propagation refers to how the electromagnetic waves travel from the transmitter to the receiver. Different types of propagation, such as line-of-sight or non-line-of-sight, require different antenna designs to optimize signal transmission. Therefore, understanding the type of propagation is crucial in choosing the right antenna for effective communication.Rate this question:
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- 39.
(211) In HF communications, by replacing the vertical antenna with a dipole antenna that’s aquarter wavelength off the ground, what are you able to get from your antenna transmission?
- A.
Higher take-off angle.
- B.
Increase efficiency.
- C.
Better reciprocity.
- D.
Twice the gain.
Correct Answer
A. Higher take-off angle.Explanation
By replacing the vertical antenna with a dipole antenna that's a quarter wavelength off the ground, you are able to achieve a higher take-off angle in your antenna transmission. This means that the signal will be radiated at a steeper angle, allowing it to reach higher altitudes and potentially cover a larger area. This can be beneficial in certain scenarios, such as when trying to communicate with stations located at higher elevations or over long distances.Rate this question:
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- 40.
(212) In siting a radio station, which foliage would have more of an adverse effect on radio wavepropagation?
- A.
Broadleaf trees.
- B.
Evergreen trees.
- C.
Swamp grass.
- D.
Sagebrush.
Correct Answer
A. Broadleaf trees.Explanation
Broadleaf trees would have more of an 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 area for the radio station. Evergreen trees, swamp grass, and sagebrush have less dense foliage and lower water content, leading to a lesser impact on radio wave propagation.Rate this question:
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- 41.
(212) What has the greatest effect on an antenna?
- A.
The sun.
- B.
The earth.
- C.
The operator.
- D.
The ionosphere.
Correct Answer
B. The earth.Explanation
The earth has the greatest effect on an antenna because it is the medium through which the antenna's signals propagate. The earth's terrain, buildings, and other obstacles can block or interfere with the antenna's signals, causing signal degradation or loss. Additionally, the earth's conductivity and electromagnetic properties can affect the antenna's performance and efficiency.Rate this question:
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- 42.
212) Which environment would be considered the most challenging for an RF transmissionsystems technician to establish and operate a radio station from?
- A.
Amazon.
- B.
North Pole.
- C.
Sahara Desert.
- D.
Sierra Nevada Mountains.
Correct Answer
A. Amazon.Explanation
The Amazon would be considered the most challenging environment for an RF transmission systems technician to establish and operate a radio station from. The dense vegetation and vast expanse of the rainforest would make it difficult to find suitable locations for tower placement and antenna installation. Additionally, the high humidity and constant rainfall in the Amazon could cause signal interference and equipment damage. The remote and inaccessible nature of the rainforest would also pose logistical challenges for transporting equipment and maintaining the radio station.Rate this question:
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- 43.
(212) Radio sets are left on 24-hours a day in a jungle environment to
- A.
Combat fungus.
- B.
Keep insects away.
- C.
Prevent short circuits.
- D.
Maintain frequency stability.
Correct Answer
C. Prevent short circuits.Explanation
In a jungle environment, the high humidity and moisture levels can increase the risk of short circuits in electronic devices like radio sets. Leaving the radio sets on 24 hours a day helps to prevent the accumulation of moisture and condensation inside the devices, reducing the chances of short circuits. By keeping the radio sets continuously powered on, the heat generated by the devices also helps to dry out any moisture that may have entered, further preventing short circuits.Rate this question:
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- 44.
(212) Which environment area will increase maintenance problems with dust and sand?
- A.
Polar.
- B.
Jungle.
- C.
Desert.
- D.
Mountainous.
Correct Answer
C. Desert.Explanation
The correct answer is Desert. Deserts are characterized by dry and arid conditions, with a lack of vegetation and high levels of dust and sand. These environmental factors can pose significant challenges for maintenance, as dust and sand can accumulate and cause damage to machinery and equipment. Additionally, the extreme temperatures and harsh conditions in deserts can also increase the wear and tear on vehicles and infrastructure, leading to increased maintenance needs.Rate this question:
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- 45.
(212) In mountainous terrain, with a mountain between you and the distant end, which of theseantennas is more effective?
- A.
Whip.
- B.
Dipole.
- C.
Discone.
- D.
Near-vertical incidence skywave.
Correct Answer
D. Near-vertical incidence skywave.Explanation
In mountainous terrain, with a mountain between you and the distant end, the near-vertical incidence skywave antenna is more effective. This is because the near-vertical incidence skywave antenna is designed to transmit signals at high angles, allowing them to bounce off the ionosphere and reach the desired destination. In mountainous terrain, where traditional line-of-sight antennas like the whip, dipole, and discone may be obstructed by the mountains, the near-vertical incidence skywave antenna can overcome this obstacle and provide better signal reception.Rate this question:
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- 46.
(213) Radio waves that travel near the earth’s surface are called
- A.
Earth waves.
- B.
Global waves.
- C.
Ground waves.
- D.
Terrestrial waves.
Correct Answer
C. Ground waves.Explanation
Radio waves that travel near the earth's surface are called ground waves. These waves are able to follow the curvature of the earth and propagate along the ground, making them suitable for communication over relatively short distances. Ground waves are commonly used for broadcasting and are able to cover large areas without the need for additional transmission equipment.Rate this question:
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- 47.
(213) The earth’s conductivity is determined by the type of
- A.
Air and moisture content in the propagation path.
- B.
Antenna being used at the time of transmission.
- C.
Soil and water in the propagation path.
- D.
Soil and air in the propagation path.
Correct Answer
C. Soil and water in the propagation path.Explanation
The earth's conductivity is determined by the type of soil and water in the propagation path. Soil and water have different levels of conductivity, which affects how well electromagnetic waves can propagate through them. Different types of soil and water have different electrical properties, such as their resistivity, which can impact the conductivity of the earth. Therefore, the conductivity of the earth is influenced by the type of soil and water present in the propagation path.Rate this question:
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- 48.
(213) Sky wave transmission is used for which type of communications?
- A.
Long distance.
- B.
Subterrestrial.
- C.
Atmospheric.
- D.
Line of sight.
Correct Answer
A. Long distance.Explanation
Sky wave transmission refers to the propagation of radio waves in the Earth's ionosphere, which allows for long-distance communication. This method is commonly used for long-distance communications such as international broadcasting and long-range maritime and aviation communication. It is able to cover large distances because the radio waves are refracted back to Earth by the ionosphere, allowing them to travel beyond the line of sight. Therefore, the correct answer is long distance.Rate this question:
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- 49.
(214) The angle at which a radio wave enters the ionosphere is known as the
- A.
Skip angle.
- B.
Critical angle.
- C.
Angle of entrance.
- D.
Angle of incidence.
Correct Answer
D. Angle of incidence.Explanation
The angle at which a radio wave enters the ionosphere is known as the angle of incidence. This is the angle between the incident wave and the normal to the surface of the ionosphere. The angle of incidence determines how the radio wave will be refracted or reflected by the ionosphere, and it is an important factor in determining the propagation characteristics of the wave. The other options, skip angle, critical angle, and angle of entrance, do not accurately describe the angle at which a radio wave enters the ionosphere.Rate this question:
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- 50.
(214) Radio waves that angled too low are
- A.
Absorbed.
- B.
Refracted.
- C.
Returned to earth.
- D.
Passed into space.
Correct Answer
A. Absorbed.Explanation
Radio waves that are angled too low are absorbed. When radio waves travel through the atmosphere, they can be affected by various factors such as the angle at which they are transmitted. If the angle is too low, the radio waves are more likely to interact with and be absorbed by objects in the atmosphere, such as buildings or trees. This absorption can result in a weaker signal or complete loss of the radio waves. Therefore, radio waves that are angled too low are absorbed rather than being refracted, returned to earth, or passed into space.Rate this question:
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