MCQ in Antennas Part 8 | ECE Board Exam

This is the Multiples Choice Questions Part 8 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 8 of the Series

351. Which beam width represents the best antenna directivity?

a. 7 degrees

b. 12 degrees

c. 19 degrees

d. 28 degrees

352. It is the ratio of the highest to the lowest frequency over which an antenna will satisfactorily operate.

a. channel ratio

b. bandwidth ratio

c. reflection ratio

d. dynamic range

353. An antenna has a power gain off 15. The power applied to the antenna is 32 W. The effective radiated power is ________.

a. 15 W

b. 32 W

c. 120 W

d. 480 W

354. It is simply a single-turn coil of wire that is significantly shorter than one wavelength and carries RF current.

a. turnstile antenna

b. loop antenna

c. rhombic antenna

d. long-wire antenna

355. A coax has an attenuation of 2.4 dB per 100 ft. The attenuation of 275 ft

a. 2.4 dB

b. 3.3 dB

c. 4.8 dB

d. 6.6 dB

356. It is group of antenna arrays that when connected together, function as a simple antenna whose beamwidth and direction can be changed electronically without having to physically move any of the individual antennas or antenna elements within the array.

a. end-fire array

b. broadside antenna

c. phased array antenna

d. log-periodic antenna

357. Conductors in multi-element antennas that do not receive energy directly from the transmission line are known as ______.

a. parasitic element

b. driven element

c. the boom

d. receptor

358. It is a broadband VHF or UHF antenna that is suited for applications for which radiating circular rather than horizontal or vertical polarized electromagnetic waves are required.

a. discone antenna

b. bicone antenna

c. log-periodic antenna

d. helical antenna

359. Mode of propagation of helical antenna where electromagnetic radiation is in the direction at right angles to the axis of the helix.

a. normal mode

b. axial mode

c. helix mode

d. helical mode

360. Mode of propagation of helical antenna where the radiation of the antenna in the axial direction and produces a broadband relatively directional pattern.

a. helical mode

b. normal mode

c. axial mode

d. helix mode

361. In a Yagi antenna, maximum direction of radiation is toward the

a. director

b. driven element

c. reflector

d. sky

362. It is defined as the ratio of the antennas maximum gain in the forward direction to its maximum gain in its backward direction

a. side-to-back ratio

b. front-to-side ratio

c. back-to-side ratio

d. front-to-back ratio

363. The horizontal radiation pattern of a vertical dipole is a ____________.

a. figure of eight

b. circle

c. narrow beam

d. clover leaf

364. An antenna that provides extremely high gain and directivity and very popular for microwave radio and satellite communications link.

a. helical antenna

b. parabolic antenna

c. hyperbolic antenna

d. log-periodic antenna

365. Part of a parabolic antenna that houses the primary antenna which radiates electromagnetic waves toward the reflector.

a. feed mechanism

b. focal point

c. center feed

d. feed antenna

366. It is a passive device that simply reflects the energy radiated by the feed mechanism into a concentrated, highly directional emission in which the individual waves are all in phase with each other.

a. director

b. parabolic segment

c. reflector

d. feed mechanism

367. The energy near the edge of the parabolic dish that does not reflect but rather is diffracted around the edge of the dish.

a. spillover

b. corona

c. dissipated power

d. copper loss

368. Determines the angular aperture of the reflector, which indirectly determines how much the primary radiation is reflected by the parabolic dish.

a. numerical aperture

b. V number

c. aperture number

d. aperture angle

369. For a 2-m diameter parabolic reflector with 10W of power radiated by the feed mechanism operating at 6 GHz with a transmit antenna efficiency of 55% and an aperture efficiency of 55%, determine the beamwidth.

a. 1.25 degrees

b. 2.25 degrees

c. 1.5 degrees

d. 1.75 degrees

370. Type of feed mechanism where the primary radiating source is located just behind a small opening at the vertex of the paraboloid rather than at the focus.

a. cassegrain feed

b. center feed

c. horn feed

d. antenna feed

371. Discone radiation pattern is

a. omnidirectional

b. unidirectional

c. figure-of-eight

d. bidirectional

372. Which is properly terminated antenna?

a. dipole

b. marconi

c. hertz

d. rhombic

373. An example of a marconi antenna is _______.

a. quarter wave vertical tower

b. collinear

c. yagi

d. rhombic

374. 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. minimum voltage and minimum current

c. equal voltage and current

d. maximum voltage and minimum current

375. Radiation resistance is the ratio of ______.

a. radiated power to the antenna center current

b. radiated power to the square of the antenna center current

c. voltage to any point of the antenna

d. square of voltage to the square of current at any point in the antenna

376. Consists of basic antenna connected to a transmission line plus one or more additional conductors

a. parasitic array

b. directors

c. driven array

d. reflectors

377. Which of the following is not a driven array?

a. yagi

b. broadside

c. collinear

d. end fire

378. What is used to determine phase difference between two broadcast antennas?

a. a phase monitor

b. a frequency monitor

c. an amplitude monitor

d. a power monitor

379. In antennas, which gives more forward gain?

a. reflector

b. driven element

c. parasitic element

d. director

380. Which of the following is longer?

a. director

b. reflector

c. driven element

d. parasitic element

381. Which is closer to the driven element?

a. parasitic element

b. driven element

c. director

d. reflector

382. How much do they differ in length from a half-wavelength?

a. 5%

b. 10%

c. 15%

d. 20%

383. How much more feed-point impedance does a folded dipole have than a normal dipole?

a. two times as much

b. three times as much

c. four times as much

d. five times as much

384. How is it possible to produce 70-ohm twin lead?

a. by folding more parasitic element

b. by manufacturing

c. by increasing the radiation resistance

d. by increasing the length of the antenna

385. With similar size parabolic, plane reflector, and corner-reflector beams, which has greater gain?

a. plane reflector

b. parabolic

c. corner-reflector beam

d. V-beam

386. With similar size, which has the narrowest lobes?

a. parabolic

b. V-beam

c. corner-reflector beam

d. plane reflector

387. Why would the wires of V-beam be closer together when used on higher frequencies?

a. main lobe lays farther to wire

b. main lobe lays closer to wire

c. secondary lobes closer to wire

d. secondary lobes farther to wire

388. How the V-beam is made unidirectional?

a. impedance terminated

b. capacitive terminated

c. inductive terminated

d. resistor terminated

389. Why might a rhombic be better than a V-beam?

a. it is resistor terminated

b. more acreage needed

c. less acreage needed

d. it is unidirectional

390. Why is the usual rhombic not frequency – sensitive?

a. unidirectional

b. with its characteristic impedance

c. less acreage required

d. main lobe is greater than back lobe

391. In what direction is the null of small diameter loop in relation to the plane of the loop?

a. 45 degrees angle

b. 180 degrees angle

c. 360 degrees angle

d. 90 degrees angle

392. When is a loop unidirectional?

a. when horizontal

b. when vertical

c. when circular

d. when unidirectional

393. Why are verticals sometimes top-loaded?

a. to resonate on high frequency

b. to decrease the electrical length

c. to resonate on low frequency

d. to look better

394. Why is pi-network superior to direct coupling to an antenna?

a. reduce harmonic radiation

b. better frequency response

c. better radiation of energy

d. reduce power dissipation

395. Why might L networks be used between an antenna and transmission line?

a. step impedance up

b. step impedance down

c. better radiation of energy

d. reduce power radiation

396. Why are antenna ammeters often shorted out or disconnected from the antenna except when readings are desired?

a. to replace it with dummy

b. not to interface with transmission

c. for proper reception of signals

d. to protect from lightning

397. Device to split transmission line current to two or more antenna towers

a. splitter

b. coupler

c. isolator

d. phasor circuit

398. What method can be used to determine the feed-point impedance of a vertical antenna?

a. resistance substitution

b. impedance matching

c. dissipated resistance measurement

d. grounding the antenna

399. In what unit is field intensity measured?

a. volts

b. amperes

c. watts/m

d. mV/m

400. How fast does low-frequency field strength attenuate?

a. directly proportional to distance

b. inversely proportional to distance

c. directly proportional to time

d. inversely proportional to time

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