1. Which fundamental concept deals with the distribution of electromagnetic energy in space and its interaction with antennas?
A) Ohm’s Law
B) Maxwell’s Equations
C) Kirchhoff’s Laws
D) Hertzian Waves
Answer: B) Maxwell’s Equations
Explanation: Maxwell’s Equations describe the behavior of electric and magnetic fields, including how they propagate through space and interact with antennas.
2. What theorem states that the total voltage in a closed circuit is equal to the sum of the individual voltage drops?
A) Ohm’s Law
B) Kirchhoff’s Voltage Law
C) Kirchhoff’s Current Law
D) Thevenin’s Theorem
Answer: B) Kirchhoff’s Voltage Law
Explanation: Kirchhoff’s Voltage Law (KVL) states that the sum of the voltage drops around any closed loop in a circuit is equal to zero.
3. What property describes the ability of an antenna to focus or direct electromagnetic radiation in a specific direction?
A) Impedance
B) Gain
C) Directivity
D) Efficiency
Answer: C) Directivity
Explanation: Directivity refers to the concentration of radiation in a specific direction by an antenna, often expressed as the ratio of radiation intensity in the desired direction to the average radiation intensity.
4. In a dipole antenna, what factor determines its directional properties?
A) Length of the antenna
B) Material composition
C) Operating frequency
D) Voltage applied
Answer: A) Length of the antenna
Explanation: The length of a dipole antenna is a crucial factor in determining its directional properties, including its radiation pattern and polarization.
5. Which type of antenna propagates electromagnetic waves along its structure without the need for external conductors?
A) Dipole antenna
B) Yagi-Uda antenna
C) Travelling-wave antenna
D) Loop antenna
Answer: C) Travelling-wave antenna
Explanation: Travelling-wave antennas, such as the Tapered Slot Antenna (TSA), propagate electromagnetic waves along their structure without requiring additional external conductors.
6. How does the feed mechanism affect the standing-wave pattern in antennas?
A) It increases the amplitude of standing waves
B) It decreases the number of standing wave nodes
C) It alters the phase relationship between incident and reflected waves
D) It has no effect on standing-wave patterns
Answer: C) It alters the phase relationship between incident and reflected waves
Explanation: The feed mechanism in antennas can alter the phase relationship between incident and reflected waves, influencing the standing-wave pattern and other antenna characteristics.
7. What is the term for an array composed of only two antenna elements?
A) Dipole array
B) Monopole array
C) Binomial array
D) Linear array
Answer: A) Dipole array
Explanation: An array consisting of only two antenna elements is commonly referred to as a dipole array.
8. Which factor primarily determines the horizontal pattern in broadcast arrays?
A) Length of individual antennas
B) Spacing between antennas
C) Operating frequency
D) Feed mechanism
Answer: B) Spacing between antennas
Explanation: The spacing between antennas in a broadcast array primarily determines the horizontal pattern, including beamwidth and directionality.
9. What term refers to the process of combining the radiation patterns of individual antennas in an array?
A) Antenna synthesis
B) Pattern multiplication
C) Beamforming
D) Array synthesis
Answer: B) Pattern multiplication
Explanation: Pattern multiplication involves combining the radiation patterns of individual antennas in an array to achieve a desired overall radiation pattern.
10. How does the Earth’s surface affect the vertical radiation pattern of antennas?
A) It increases gain
B) It decreases directivity
C) It introduces reflections and ground waves
D) It has no significant effect
Answer: C) It introduces reflections and ground waves
Explanation: The Earth’s surface affects the vertical radiation pattern of antennas by introducing reflections and ground waves, which can modify the pattern’s shape and intensity.
11. What type of antenna array employs a series of progressively shorter elements to achieve a tapered radiation pattern?
A) Uniform array
B) Binomial array
C) Collinear array
D) Yagi-Uda array
Answer: B) Binomial array
Explanation: A binomial array consists of a series of progressively shorter elements, arranged to achieve a tapered radiation pattern with desired characteristics.
12. What physical quantity represents the concentration of radiated power in a particular direction compared to an isotropic radiator?
A) Impedance
B) Directivity
C) Efficiency
D) Gain
Answer: D) Gain
Explanation: Gain represents the concentration of radiated power in a particular direction compared to an isotropic radiator, often expressed in decibels (dBi).
13. What property of an antenna determines its ability to intercept or transmit electromagnetic energy efficiently?
A) Gain
B) Directivity
C) Effective area
D) Efficiency
Answer: C) Effective area
Explanation: Effective area refers to an antenna’s ability to intercept or transmit electromagnetic energy efficiently, taking into account its physical size and other factors.
14. Which theorem states that any linear electrical network with voltage and current sources can be replaced by an equivalent circuit consisting of a single voltage source and a single series resistor?
A) Norton’s Theorem
B) Superposition Theorem
C) Thevenin’s Theorem
D) Reciprocity Theorem
Answer: C) Thevenin’s Theorem
Explanation: Thevenin’s Theorem states that any linear electrical network with voltage and current sources can be replaced by an equivalent circuit consisting of a single voltage source and a single series resistor.
15. What is the primary purpose of multiplying the patterns of individual antennas in an array?
A) To increase the operating frequency
B) To decrease impedance
C) To improve directivity
D) To reduce radiation efficiency
Answer: C) To improve directivity
Explanation: Multiplying the patterns of individual antennas in an array is primarily done to improve directivity, focusing radiation in desired directions and reducing radiation in unwanted directions.