Online Questions and Answers Topic Outline
- MCQs in Basic considerations
- MCQs in Wire Radiators in Space
- MCQs in Isotropic Radiator
- MCQs in Current and Voltage Distributions
- MCQs in Resonant and Non-resonant Antennas
- MCQs in Antenna Terms and Definition
- MCQs in Antenna Gain and Resistance
- MCQs in Bandwidth, Beamwidth and Polarization
- MCQs in Grounded and Ungrounded Antennas
- MCQs in Grounding Systems and Matching Systems
- MCQs in Antenna Types
- MCQs in Directional and Non-directional Antennas
- MCQs in Microwave Antennas
- MCQs in Wideband and Special Purpose Antennas
MCQs in Antennas Series
Following is the list of multiple choice questions in this brand new series:
Continue Practice Exam Test Questions Part VIII 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
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