# MCQ in Radiation and Wave Propagation Part 7 | ECE Board Exam

(Last Updated On: May 3, 2020) This is the Multiples Choice Questions Part 7 of the Series in Radiation and Wave Propagation 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.

#### MCQ Topic Outline included in ECE Board Exam Syllabi

• MCQ in Wave Propagation
• MCQ in Wavelength Calculations
• MCQ in Diversity Systems

#### Continue Practice Exam Test Questions Part 7 of the Series

301. Whether or not polarization of an antenna is linear depends on changes in direction in which:

a. The direction in which the electric plane is radiated.

b. The horizontal or vertical plane of the electric wave.

c. The direction in which magnetic wave is radiated.

d. None of these

Solution:

302. The D, E and F layers of the ionosphere are called

a. Mark-Space Layers

b. Davidson-Miller Layers

c. Kenelly Heaviside Layers

d. Maxwell Layer

Solution:

303. ________ refers to the ratio of an electric field component to a magnetic field component at the same point of the wave.

a. Characteristics impedance

c. Intrinsic impedance

d. Wave impedance

Solution:

304. The field strength of a radio signal varies according to the output or transmitted power and the distance of the receiver from the transmitter. This wave behavior is described by

a. The field strength

b. Huygen’s Principle

d. Inverse Square Law

Solution:

305. The antenna theory states that reception and transmission functions are interchangeable is

a. Poynting Theorem

b. Snell’s Law

c. Huygen’s Principle

d. Law of Reciprocity

Solution:

306. The frequency band where electromagnetic waves travel in straight path or in a direct line of sight between the transmitter and receiver antenna is

a. ELF

b. HF

c. VLF

d. VHF and above

Solution:

307. This mode of electromagnetic wave propagation uses the earth’s surface or curvature as a guide to transmit vertically polarized waves

a. Sky wave

b. Tropospheric wave

c. Transionospheric wave

d. Ground wave

Solution:

308. Frequencies in the UHF range propagate by means of

a. Ground waves

b. surface waves

c. sky waves

d. space waves

Solution:

309. the ground wave eventually disappear as it moves farther away from the transmitter, because of

a. tilting

b. reflection

c. refraction

d. diffraction

Solution:

310. as electromagnetic waves travel in free space, only one of the following can happen

a. absorption

b. attenuation

c. refraction

d. reflection

Solution:

311. In polarization diversity, two signals are

a. Both polarized at one specific location

b. Vertically and horizontally polarized separately

c. Polarized in the same manner

d. Vertically and horizontally polarized using a common antenna

Solution:

312. If the direction of the electric field of a radio wave is horizontal. That wave is known to be _____ polarized.

a. Negatively

b. Vertically

c. Positively

d. Horizontally

Solution:

313. The property of a material that determines how much change electrostatic energy can be stored per unit volume when voltage is applied

a. Miller effect

b. Permeability

c. Capacitance

d. Permitivity

Solution:

314. According to this law or principle, a wavefront may be considered to consist of an infinite number of isotropic radiators, each one sending out wavelets, always away from the source.

a. Snell’s Law

b. Maxwell’s Law

c. Huygen’s Principle

d. Archimedes Principle

Solution:

315. A number, which when multiplied by the speed of light in free space gives the speed of light in the medium in question is

a. Fibonacci number

b. Fermat’s number

c. Velocity factor

d. K-factor

Solution:

316. The ability of a radio wave to be bent slightly over the edge of a sharp obstacle such as a steep hill or mountain top is

a. Diffraction

b. Reflection

c. Refraction

d. Attenuation

Solution:

317. A space wave is

a. Sky wave

c. Surface wave

d. Line of sight propagation wave

Solution:

318. It is a diagram indicating the intensity in volts/meter, in all directions, of the radiated filed of an antenna as it would occur under actual operating conditions.

a. Constellation diagram

b. Argand diagram

c. Funicular diagram

Solution:

319. Equivalent to capacitance in electrical circuits

a. Inductance

b. Permittivity

c. Permeability

d. Power density

Solution:

320. All of these cause attenuation except

a. Tilting

b. Ground absorption

c. Atmospheric absorption

d. Surface wave propagation

Solution:

321. The transmission of radio waves far beyond line of sight distances by using high power and large transmitting antennas to beam the signal upward into the atmosphere and a similar large receiving antenna to pick up a small portion of the signal scattered by the atmosphere is called

a. Forward scatter propagation

b. Beyond the horizon propagation

c. Either a or b

d. Meteoric Scatter Propagation

Solution:

322. The apparent height of an ionized layer of the atmosphere; as determined from the time interval between the transmitted signal and the ionospheric echo at vertical incidence. This height is the maximum height reached if the actual paths are projected forming straight lines from the ascent to the descent of waves.

a. Optimum height

b. Virtual height

c. Complex height

d. Critical height

Solution:

323. The highest frequency whereby a wave will be returned back to earth by an ionospheric layer having been beamed up at it and ranges from 5 to 12 MHz. For F2 layers. This frequency is directly proportional to the secant function of the smallest angle, which allows reflection of sky waves.

a. Apex frequency

b. Critical frequency

c. Carrier frequency

d. Baseband frequency

Solution:

324. The distant at which sky-wave signals are reflected back to earth depend on

a. Height of the reflecting layer

b. The takeoff angle of the waves

c. Both a and b

d. Conductivity of the soil

Solution:

325. Perfect reflection of waves occur when

a. The magnitude of the incident is equal to the reflected waves

b. The magnitude of the incident is less than the reflected waves

c. The magnitude of incident is greater than reflected waves

d. Both a and b

Solution:

326. The process by which a radio wave is bent and returned to earth from one medium to another after striking them is

a. Reflection

b. Refraction

c. Diffraction

d. Absorption

Solution:

327. An incident, traveling obliquely from one medium to another, will undergo a change in direction if the velocity of the wave in one medium is different from that in the other and the ratio of the sine of the angle of incidence to the sine of the angle of refraction is the same ratio of respectively wave velocities in these media. This law is called

a. Snell’s Law

b. Fisher’s Law

c. Hooke’s Law

d. Newton’s Law

Solution:

328. The lowest layer of the ionosphere which exists between 50 to 90 km from the earth’s surface and reflects VLF and LF waves while absorbing MF and HF waves during daytime is the

a. D layer

b. E layer

c. F layer

d. Vantress layer

Solution:

329. This phenomenon occurs when the thicker air is on top instead of being at the bottom when the temperature of water vapor gradient is lesser or greater than the standard rate.

a. Thermal inversion

b. Horizontal ducting

c. Elevated ducting

Solution:

330. An ionospheric layer, which exists between 90 to 120 km above the earth’s surface and is about 25 km thick. It aids MF surface propagation while reflecting some HF during daytime

a. D-layer

b. E-layer

c. F layer

d. Vantress layer

Solution:

331. Atmospheric condition is controlled by

a. Pressure

b. Temperature

c. Humidity

d. All of these

Solution:

332. This ionospheric layer forms at night at about 300 km from the earth’s surface and is responsible for long distance HF wave propagation due to reflection and refraction. It splits during daytime due to the ionizing energy from ultraviolet rays of the sun.

a. D layer

b. E layer

c. F layer

d. Vantress layer

Solution:

333. When the transmitting and receiving antennas are line-of-sight of each other, the mode of propagation is _____ wave.

a. Space or direct

b. Sky

c. surface

d. ground

Solution:

334. Power density is inversely proportional to the square of the distance from the source or transmitter to the destination or receiver. This law is called:

a. Coulomb’s law

b. Law of Universal Gravitation

c. Inverse Square Law

d. Lenz’s Law

Solution:

335. A one-hop, full duplex, microwave system is in a space diversity arrangement. Determine how many receivers in all are used?

a. 6

b. 2

c. 8

d. 4

Solution:

336. ________ is the extra ionization of the E-layer resulting to irregular and intermittent reflection of frequencies of up to 80 MHz in temperate and lower latitudes of frequencies of up to 80 MHz in temperate and lower latitudes. It is variable in time of occurrence, height. Geographical distribution, penetration frequency and ionization density.

b. Dillinger Effect

d. Scintillations

Solution:

337. The decrease in signal strength as a result of absorption or scattering of energy along a transmission path is called:

a. Attenuation

b. Microbending

c. Dispersion

Solution:

338. The transfer of electromagnetic waves or acoustical energy from one place to another through a suitable transmission medium is

a. Wave propagation

b. RF induction

d. Forward Scatter

Solution:

339. The upper limit of frequencies that can be used at a specified time for radio transmission between two points and involving propagation by reflection from regular ionized layers of the ionosphere is

a. Maximum usable frequency

b. Optimum traffic frequency

c. Minimum usable frequency

d. Carrier frequency

Solution:

340. Waves whose oscillations are perpendicular to the direction of propagation are called

a. Huygen’s waves

b. Transverse waves

c. Longitudinal waves

d. Fraunhoffer waves

Solution:

341. Indicate which one of the following terms applies to troposcatter propagation:

a. SIDs

c. Atmospheric storms

Solution:

342. VLF waves are used for some types of services because

a. Of the low power required

b. The transmitting antennas are of convenient size

c. They are very reliable

d. They penetrate the ionosphere easily

Solution:

343. High frequency waves are

a. Absorbed by the F2 layer

b. Reflected by the D layer

c. Capable of use for long-distance communications on the moon

d. Affected by the solar cycle

Solution:

344. Distances near the skip distance should be used for sky-wave propagation

a. To avoid tilting

b. To prevent sky-wave and upper ray interference

c. To avoid the faraday effect

d. So as not to exceed the critical frequency

Solution:

345. The ground wave eventually disappears, as one moves away from the transmitter, because of

a. Interference from the sky wave

b. Loss of line of sight conditions

c. Maximum single-hop distance limitation

d. Tilting

Solution:

346. In electromagnetic waves, polarization

a. Is caused by reflection

b. Is due to the transverse nature of the waves

c. Results from the longitudinal nature of the waves

d. Is always vertical in an isotropic medium

Solution:

d. None of these

Solution:

348. The absorption of radio waves by the atmosphere depends on

a. Their frequency

b. Their distance from the transmitter

c. The polarization of the waves

d. The polarization of the atmosphere

Solution:

349. Electromagnetic waves are refracted when they

a. Pass into a medium of different dielectric constant

b. Are polarized at right angles to the direction of propagation

c. Encounter a perfectly conducting surface

d. Pass through a small slot in a conducting plane

Solution:

350. Diffraction of electromagnetic waves

a. Is caused by reflection from the ground

b. Arises only with spherical wavefronts

c. Will occur when the waves pass through a large slot

d. May occur around the edge of a sharp obstacle

Solution:

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

MCQ in Radiation and Wave Propagation
PART 1: MCQ from Number 1 – 50                        Answer key: PART 1
PART 2: MCQ from Number 51 – 100                   Answer key: PART 2
PART 3: MCQ from Number 101 – 150                 Answer key: PART 3
PART 4: MCQ from Number 151 – 200                 Answer key: PART 4
PART 5: MCQ from Number 201 – 250                 Answer key: PART 5
PART 6: MCQ from Number 251 – 300                 Answer key: PART 6
PART 7: MCQ from Number 301 – 350                 Answer key: PART 7
PART 8: MCQ from Number 351 – 400                 Answer key: PART 8

### Complete List of MCQ in Communications Engineering per topic

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