# MCQs in Radiation and Wave Propagation Part VII

Compiled MCQs in Radiation and Wave Propagation Part 7 of the series as one topic in Electronic System and Technologies (Communications Engineering) in the ECE Board Exam.

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.

### Online Questions and Answers Topic Outline

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

### MCQs in Radiation and Wave Propagation Series

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

PART 1: MCQs from Number 1 – 50                        Answer key: PART I
PART 2: MCQs from Number 51 – 100                   Answer key: PART II
PART 3: MCQs from Number 101 – 150                 Answer key: PART III
PART 4: MCQs from Number 151 – 200                 Answer key: PART IV
PART 5: MCQs from Number 201 – 250                 Answer key: PART V
PART 6: MCQs from Number 251 – 300                 Answer key: PART VI
PART 7: MCQs from Number 301 – 350                 Answer key: PART VII
PART 8: MCQs from Number 351 – 400                 Answer key: PART VIII

### Continue Practice Exam Test Questions Part VII 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

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

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

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

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

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

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

308. Frequencies in the UHF range propagate by means of

• a. Ground waves
• b. surface waves
• c. sky waves
• d. space waves

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

• a. tilting
• b. reflection
• c. refraction
• d. diffraction

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

• a. absorption
• b. attenuation
• c. refraction
• d. reflection

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

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

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

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

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

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

317. A space wave is

• a. Sky wave
• c. Surface wave
• d. Line of sight propagation wave

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

319. Equivalent to capacitance in electrical circuits

• a. Inductance
• b. Permittivity
• c. Permeability
• d. Power density

320. All of these cause attenuation except

• a. Tilting
• b. Ground absorption
• c. Atmospheric absorption
• d. Surface wave propagation

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

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

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

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

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 and b

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

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

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

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

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

331. Atmospheric condition is controlled by

• a. Pressure
• b. Temperature
• c. Humidity
• d. All of these

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

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

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

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

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

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

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

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

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

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

• a. SIDs
• c. Atmospheric storms

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

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

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

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

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

• d. None of these

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

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

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

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

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