This is the Multiples Choice Questions Part 6 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

- 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:

**Antennas MCQs**

**MCQs from Number 1 – 50**Answer key:

**PART I**

**MCQs from Number 51 – 100**Answer key:

**PART II**

**MCQs from Number 101 – 150**Answer key:

**PART III**

**MCQs from Number 151 – 200**Answer key:

**PART IV**

**MCQs from Number 201 – 250**Answer key:

**PART V**

**MCQs from Number 251 – 300**Answer key:

**PART VI**

**MCQs from Number 301 – 350**Answer key:

**PART VII**

**MCQs from Number 351 – 400**Answer key:

**PART VIII**

**MCQs from Number 401 – 450**Answer key:

**PART IX**

**MCQs from Number 451 – 500**Answer key:

**PART X**

### Continue Practice Exam Test Question Part VI of the Series

251. It is a metallic conductor system capable of radiating and capturing electromagnetic energy

- a. transmission lines
- b. antenna
- c. waveguides
- d. load

252. A directional antenna with two or more elements is known as

- a. folded dipole
- b. ground plane
- c. loop
- d. array

253. The ratio of the focal length to the diameter of the mouth of the parabola is called _____.

- a. aperture
- b. focal point
- c. foci
- d. major axis

254. The impedance of a dipole is about

- a. 50-ohm
- b. 73-ohm
- c. 93-ohm
- d. 300-ohm

255. A special type of transmission line that consist of conducting metallic tube through which high frequency electromagnetic energy is propagated

- a. medium
- b. microstrip
- c. stripline
- d. waveguide

256. Calculate the angle of declination for an antenna using a polar mount at a latitude of 45 degrees

- a. 3.2 degrees
- b. 1.3 degrees
- c. 4.2 degrees
- d. 6.81 degrees

257. The cone angle of the flare angle of a conical horn antenna is approximately

- a. 55 degrees
- b. 45 degrees
- c. 40 degrees
- d. 50 degrees

258. Electrical energy that has escaped into free space in the form of transverse electromagnetic waves

- a. Radio waves
- b. Frequency
- c. Signal
- d. Wavelength

259. The length of the ground plane vertical at 146 MHz is

- a. 1.6 ft
- b. 1.68 ft
- c. 2.05 ft
- d. 3.37 ft

260. Using a small reflector to beam waves to the larger parabolic reflector is known as

- a. Focal feed
- b. Horn feed
- c. Cassegrain feed
- d. Coax feed

261. The plane parallel to the mutually perpendicular line in the electric and magnetic fields is called _______.

- a. wavefront
- b. point source
- c. isotropic source
- d. rays

262. What is the beamwidth of a parabolic antenna with a diameter of 5 meters and an operating frequency of 10 GHz?

- a. 0.5 degrees
- b. 0.675 degrees
- c. 0.348 degrees
- d. 3.48 degrees

263. The horizontal radiation pattern of a dipole is a

- a. circle
- b. figure of eight
- c. clover leaf
- d. narrow beam

264. The size of antenna is inversely proportional to _______.

- a. frequency
- b. power
- c. radiation resistance
- d. wavelength

265. A popular half – wave antenna is the

- a. Ground plane
- b. End-fire
- c. Collinear
- d. Dipole

266. Calculate the gain of a parabolic antenna using a 2.5-m radius dish operating at 10 GHz.

- a. 166.673 dB
- b. 83.7 dB
- c. 52.2 dB
- d. 45.6 dB

267. It is the ratio of the radiated to the reflected energy

- a. Radiation resistance
- b. Radiation efficiency
- c. Radiation constant
- d. Radiation antenna

268. The feed mechanism in a parabolic antenna that radiates the electromagnetic energy.

- a. Primary antenna
- b. Reflectors
- c. Secondary antenna
- d. Focal point

269. It is a polar diagram or graph representing field strengths or power densities at various angular positions relative to an antenna

- a. Side lobe
- b. Front lobe
- c. Radiation pattern
- d. Radiation constant

270. For a transmit antenna with a radiation resistance of 72 ohms, an effective antenna resistance of 8 ohms, a directive gain of 20 and an input power of 100W, determine the antenna gain.

- a. 12.55 dB
- b. 10.43 dB
- c. 11.21 dB
- d. 9.78 dB

271. The radiation pattern plotted in terms of electric field strength or power density

- a. absolute radiation pattern
- b. relative radiation pattern
- c. absolute front lobe pattern
- d. absolute side lobe pattern

272. Calculate the characteristic impedance of a quarter – wavelength section used to connect a 300-ohm antenna to a 75-ohm line

- a. 150 ohms
- b. 120 ohms
- c. 130 ohms
- d. 110 ohms

273. Plots of field strength or power density with respect to the value at a reference point

- a. absolute front lobe pattern
- b. relative front lobe pattern
- c. relative front lobe pattern
- d. relative radiation pattern

274. What must be the height of a vertical radiator one half wavelength high if the operating frequency is 1100 kHz?

- a. 120 m
- b. 136 m
- c. 115 m
- d. 124 m

275. Lobes adjacent to the front lobe

- a. Diagonal lobes
- b. Side lobes
- c. Front lobes
- d. Back lobes

276. Lobes in a direction exactly opposite of the front lobe

- a. Side lobes
- b. Adjacent lobes
- c. Front lobes
- d. Back lobes

277. Calculate the efficiency of an antenna that has a radiation resistance of 73 ohms and an effective dissipation resistance of 5 ohms

- a. 98.3%
- b. 93.6%
- c. 90.7%
- d. 95.5%

278. The line bisecting the major lobe, or pointing from the center of the antenna in the direction of maximum radiation is called _______.

- a. line of shoot
- b. diagonal shoot
- c. bisecting shoot
- d. antenna shoot

279. The ammeter connected at the base of a Marconi antenna has a certain reading. If this reading is increased 2.77 times, what is the increase in output power?

- a. 3.45
- b. 1.89
- c. 2.35
- d. 7.67

280. Refers to a field pattern that is close to the antenna.

- a. Induction field
- b. Far field
- c. Radiation field
- d. Capture field

281. A half-wave dipole is driven with a 5-W signal at 225 MHz. A receiving dipole 100 km. Calculate the received power into a 73-ohm receiver.

- a. 23.5 pW
- b. 7.57 pW
- c. 5.64 pW
- d. 1.26 pW

282. It is the resistance that, if it replaced the antenna, would dissipate exactly the same amount of power that the antenna radiates.

- a. Directive gain
- b. Antenna efficiency
- c. Radiation resistance
- d. Antenna resistance

283. What is the effective radiated power of a television broadcast station if the output of the transmitter is 1000W, antenna transmission line loss is 50W, and the antenna power gain is 3?

- a. 1250 W
- b. 2370 W
- c. 2130 W
- d. 2850 W

284. It is the ratio of the power radiated by an antenna to the sum of the power radiated and the power dissipated.

- a. radiation resistance
- b. coupling coefficient
- c. antenna efficiency
- d. antenna beamwidth

285. It is the ratio of the power radiated by the antenna to the total input power.

- a. antenna efficiency
- b. reflection coefficient
- c. standing wave ratio
- d. radiation resistance

286. If a 500 kHz transmitter of a constant power produces field strength of 100 uV/m at a distance of 100 mi from the transmitter, what would be the theoretical field strength at a distance of 200 mi from the transmitter?

- a. 45 uV/m
- b. 100 uV/m
- c. 50 uV/m
- d. 35 uV/m

287. An antenna that transmits or receives equally well in all directions is said to be _____.

- a. omnidirectional
- b. bidirectional
- c. unidirectional
- d. quasidirectional

288. It is the ratio of the power density radiated in a particular direction to the power density radiated to the same point by a reference antenna, assuming both antennas are radiating the same amount of power

- a. power gain
- b. directive gain
- c. total gain
- d. system gain

289. If the field intensity of 25 mV/m develops 2.7 V in a certain antenna, what is its effective height?

- a. 110 m
- b. 100 m
- c. 98 m
- d. 108 m

290. The magnetic field of an antenna is perpendicular to the earth. The antenna’s polarization ______.

- a. is vertical
- b. is horizontal
- c. is circular
- d. cannot be determined from the information given

291. If the power of a 500 kHz transmitter is increased from 150 W to 300 W, what would be the percentage change in field intensity at a given distance from the transmitter?

- a. 141%
- b. 150%
- c. 100%
- d. 133%

292. It is the same with directive gain except that the total power fed to the antenna is used and the antenna efficiency is taken into account.

- a. system gain
- b. power gain
- c. directive gain
- d. total gain

293. A hip-radio telephone transmitter operates on 2738 kHz. At a certain point distant from the transmitter, the 2738 kHz signal is measured field of 147 mV/m. The second harmonic field at the same point is measured as 405 uV/m. To the nearest whole unit in decibels, how much has the harmonic emission been attenuated below the 2738 kHz fundamental?

- a. 43.2 dB
- b. 51.2 dB
- c. 35.1 dB
- d. 25.1 dB

294. It is the equivalent power that an isotropic antenna would have to radiate to achieve the same power density in the chosen direction at a given point as another antenna.

- a. EIRP
- b. ERP
- c. IRL
- d. RSL

295. When the energy is applied to the antenna at a point of high – circulating current.

- a. voltage-fed antenna
- b. power-fed antenna
- c. current-fed antenna
- d. impedance-fed antenna

296. For a transmit antenna with a power gain of 10 and an input power of 100 W, determine the EIRP in watts.

- a. 30 dBW
- b. 40 dBW
- c. 50 dBW
- d. 20 dBW

297. If energy is applied at the geometrical center of antenna, the antenna is said to be _____.

- a. center-fed
- b. end-fed
- c. quarterwave-fed
- d. halfwave-fed

298. For a transmit antenna with a power gain of 10 and an input power of 100 W, determine the power density at a point 10 km from the transmit antenna

- a. 0.574 uW/m^2
- b. 0.796 uW/m^2
- c. 1.24 uW/m^2
- d. 0.981 uW/m^2

299. For a transmit antenna with a radiation resistance of 72 ohms, an effective antenna resistance of 8 ohms, a directive gain of 20 and an input power of 100 W, determine the antenna efficiency.

- a. 90%
- b. 96%
- c. 98%
- d. 96%

300. The fields surrounding the antenna do not collapse their energy back into the antenna but rather radiate it out in space.

- a. induction field
- b. near field
- c. radiation field
- d. magnetic field