MCQ in Antennas Part 10 | ECE Board Exam

This is the Multiples Choice Questions Part 10 of the Series in Antennas as one of the Communications Engineering topic. In Preparation for the ECE Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including but not limited to past Board Examination Questions in Electronic System and Technologies, Communications Books, Journals and other Communications References.

Online Questions and Answers Topic Outline

• MCQ in Basic considerations
• MCQ in Wire Radiators in Space
• MCQ in Isotropic Radiator
• MCQ in Current and Voltage Distributions
• MCQ in Resonant and Non-resonant Antennas
• MCQ in Antenna Terms and Definition
• MCQ in Antenna Gain and Resistance
• MCQ in Bandwidth, Beamwidth and Polarization
• MCQ in Grounded and Ungrounded Antennas
• MCQ in Grounding Systems and Matching Systems
• MCQ in Antenna Types
• MCQ in Directional and Non-directional Antennas
• MCQ in Microwave Antennas
• MCQ in Wideband and Special Purpose Antennas

Continue Practice Exam Test Questions Part 10 of the Series

451. A type of array antenna which consists of one half-wave driven dipole, one reflector and one director.

a. Log periodic dipole array

b. Yagi-uda

c. Herztian dipole

d. Broadside collinear

452. It is measure of the microwave power radiated from an antenna as a function of angular direction from the antenna axis.

a. Polarization

b. Sidelobes

c. Beamwidth

d. Antenna pattern

453. What is the gain of four identically polarized antennas stacked one above the other fed in phase?

a. 4 dB over the gain of one antenna

b. 10 dB over the gain of one antenna

c. 3 dB over the gain of one antenna

d. 6 dB over the gain of one antenna

454. Gain of an isotropic antenna.

a. 1 dB

b. -1 dB

c. 0 dB

d. 2 dB

455. A dipole antenna requires to be fed with 20 kW of power to produce a given signal strength to a particular distant point. If the addition of a reflector makes the same field strength available with an input power of 11 kW, what is the gain in dB obtained by the use of the reflector? (Gain referred to this particular dipole)

a. 4. 75

b. 1.81

c. 4.24

d. 2.6

456. Top loading is used in an antenna in order to increase its __________________.

a. Bandwidth

b. Beamwidth

c. Input capacitance

d. Effective height

457. A horizontal antenna is

a. Perpendicularly polarized

b. Centrally polarized

c. Horizontally polarized

d. Vertically polarized

458. The frequency of operation of a dipole antenna cut to length of 3.4 m.

a. 42.9 MHz

b. 53.3 MHZ

c. 38.5 MHz

d. 61.3 MHz

459. Two or more antennas separated by 9 wavelengths are used.

a. Frequency diversity

b. Space diversity

c. Hybrid diversity

d. Polarized diversity

460. A convenient method of determining antenna impedance.

a. Trial and error

b. Stub matching

c. Smith chart

d. Reactance circle

461. Width measured in degrees of a major lobe between end of the lobe at which the relative power is one half (-3 dB) its value from the peak of the lobe.

a. Radiation

b. Wavelength

c. Bandwidth

d. Beamwidth

462. An increase in the effective power radiated by an antenna in a certain desired direction at the expense of power radiated in other directions.

a. Antenna gain

b. Antenna efficiency

c. Antenna total ratio

d. Antenna back lobe ratio

463. Where does the maximum current and minimum voltage value on a resonant Hertz dipole exist?

a. Center of the antenna

b. Ends of the antenna

c. Near the center of the antenna

d. Near the end of the antenna

464. How can the antenna efficiency of a HF grounded vertical antenna be made comparable to that of a half-wave antenna?

a. By isolating the coax shield from ground

b. By installing a good ground radial system

c. By shortening the vertical

d. By isolating the coax shield from ground

465. Known as the technique for adding a series inductor at or near the center of an antenna element in order to cancel the capacitive reactance of an antenna.

a. Reflector

b. Center loading

c. Dipole

d. Loading coil

466. What is meant by the term antenna bandwidth?

a. The angle between the half-power radiation points

b. The angle formed between two imaginary lines drawn through the ends of the elements

c. The frequency range over which an antenna can be expected to perform well

d. Antenna length divided by the number of elements

467. Where does the voltage node of a half-wave antenna exist?

a. At feed point

b. Near the feed point

c. Near the center

d. At center

468. This is a flexible vertical rod antenna commonly used on mobiles.

a. Hertz

b. Ground plane

c. Whip

d. Marconi

469. What is a dummy antenna?

a. A non-directional transmitting antenna

b. An antenna used for hand-held ratio

c. One which is used as a reference for gain measurements

d. A non-radiating load for a transmitter used for testing

470. Best description of a collinear and broadside antenna radiation pattern.

a. Bidirectional

b. Omnidirectional

c. Unidirectional

d. Perfect circle

471. What is a driven element of an antenna?

a. Always the forward most element

b. Always the rearmost element

c. The element fed by the transmission line

d. The element connected to the rotator

472. Antenna which is not properly terminated

a. Whip

b. Non-resonant

c. Isotropic

d. Resonant

473. At the ends of a half-wave antenna, what values of current and voltage exist compared to the remainder of the antenna?

a. Minimum voltage and maximum current

b. Maximum voltage and minimum current

c. Minimum voltage and minimum current

d. Equal voltage and current

474. Refers to a type of beam antenna which uses two or more straight elements arranged in line with each other.

a. Whip antenna

b. Yagi antenna

c. Rhombic antenna

d. Dipole antenna

475. What is meant by the term radiation resistance for an antenna?

a. Losses in the antenna elements and feed line

b. An equivalent resistance that would dissipate the same amount of power as that radiated from an antenna

c. The resistance in the trap coils to received signal

d. The specific impedance of the antenna

476. Which of the following parts of the radio receiver represents the component that extracts the desired RF signal from the electromagnetic wave?

a. Detector

b. Antenna

c. Crystal

d. AF amplifier

477. Determine the dB of a receiving antenna which delivers a microvolt signal to a transmission line over that of an antenna that delivers a 20 microvolt signal under identical circumstances.

a. -26 dB

b. 26 dB

c. 3 dB

d. 10 dB

478. What is the term for the ratio of the radiation resistance of an antenna to the total resistance of the system?

a. Antenna efficiency

b. Radiation conversion loss

c. Beamwidth

d. Effective radiated power

479. One of the following prevents a transmitter from emitting a signal that interferes with other station on frequency during the test.

a. Use of shielded antenna radiator

b. Use of low height antenna

c. Use of dummy antenna

d. Use of grounded antenna

480. In high frequency radio transmission, the lower the radio frequency the _______________ of the antenna.

a. Longer the length

b. Bigger the diameter

c. Shorter length

d. Smaller the diameter

481. Which of the following antenna where its beamwidth is determined by the dimensions of its lens or reflector?

a. Whip antenna

b. Aperiodic antenna

c. Aperture antenna

d. Long wire antenna

482. What measure will you adopt on the antenna system of a VHF or UHF mobile transceivers that has very low height antenna?

a. Increase transmitter to antenna cable

b. Use directional antenna

c. Check grounding system

d. Provide loading coil

483. In order to have an effective radio antenna, the design of its radiator must have a minimum length equivalent to ________________.

a. λ/10

b. λ/4

c. λ/14

d. λ/6

484. What is a parasitic element of an antenna?

a. An element dependent on the antenna structure for support.

b. A transmission line that radiates radio-frequency energy.

c. An element that receives its excitation from mutual coupling rather than from a transmission line.

d. An element-polarized 90 degrees opposite the driven element.

485. At what position does a maritime ship main antenna have when it is open circuited and that any auxiliary is/are connected to the main receiver?

a. AA

b. Emergency transmitter

c. Direction finder

d. Ground

486. Due to the presence of parallel LC networks in the trap antenna, one of the following is a disadvantage of using this kind of antenna.

a. Radiate harmonics

b. Reduce power

c. Reduce beamwidth

d. Allow entry of interference

487. How do you compare the length of the reflector element of a parasitic beam antenna with that of its driven element?

a. Same length

b. Reflector element is 5% longer

c. Reflector element is half shorter

d. Reflector element is 5% shorter

488. Which of the following statements refers to a reason why intelligence signal cannot be transmitted directly on their frequency?

a. Their frequencies are high and are susceptible to noise

b. Their frequencies are high and need very large antennas

c. Their frequencies are low and need very large antennas

d. Their frequencies are low and need very small antennas

489. What is the purpose of a certain antenna component composed of a parallel LC networks inserted in the antenna called traps?

a. Cancel the capacitive reactance of an antenna

b. Enhance directivity

c. Produce resonant system at specific frequency

d. Provide a multiband operation

490. Refers to the numerical ratio relating to the radiated signal strength of an antenna to that of another antenna.

a. Antenna loss

b. Antenna gain

c. Antenna bandwidth

d. Antenna efficiency

491. How much longer or shorter does the length of the director element of parasitic beam antenna compared with that of the driven element?

a. About 5% shorter

b. Around 10% longer

c. One half longer

d. Around 5% longer

492. Refers to the ratio of radiated to reflected energy.

a. Front-to-back ratio

b. Antenna efficiency

c. Radiation efficiency

d. Signal-to-noise ratio

493. A half-wave dipole antenna

a. Hertz

b. Marconi

c. Parabolic

d. Vertical monopole

494. When conductors are spread out in a straight line to a total length of one-quarter wavelength, the antenna is called what?

a. Marconi

b. Vertical monopole

c. Quarter-wave dipole

d. All of these

495. What do you call of a polar diagram or graph representing field strengths or power densities at various angular positions relative to an antenna?

a. Venn diagram

b. Figure-8 pattern

c. Lissajous figure

d. Radiation pattern

496. ________________ is the ratio of the front lobe power to the back lobe power.

a. Front-to-side ratio

b. Front-to-back ratio

c. Back-to-front ratio

d. Minor-to-major ratio

497. It is defined as the area within a distance D2/λ from the antenna, where λ is the wavelength and D is the antenna diameter in the same units.

a. Far field

b. Near field

c. Green field

d. Radiation field

498. What is the ratio of the power radiated by the antenna to the total input power?

a. Power gain

b. Directive gain

c. Antenna efficiency

d. Radiation efficiency

499. _________________ of an antenna refers to the orientation of the electric field radiated from it.

a. Radiation

b. Bandwidth

c. Beamwidth

d. Polarization

500. Pertains to a wire structure placed below the antenna and erected above the ground. It is a form of capacitive ground system.

a. Image

b. Counterpoise

c. Antenna orientation

d. Antenna polarization

Questions and Answers in Antennas Series

Following is the list of multiple choice questions in this brand new series:

Complete List of MCQ in Communications Engineering per topic