MCQs in Antennas Part IV

This is the Multiples Choice Questions Part 4 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

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

PART 9: MCQs from Number 401 – 450                 Answer key: PART IX

PART 10: MCQs from Number 451 – 500                 Answer key: PART X

SEE: More Questions and Answers in Antennas

Continue Practice Exam Test Questions Part IV of the Series

151. A discone antenna is a radiator whose impedance can be directly matched to what type of coaxial transmission line?

• a. 70 ohm line
• b. 30 ohm line
• c. 300 ohm line
• d. 50 ohm line

152. In order to increase the gain of Yagi-Uda arrays, what element are added?

• a. Using many director
• b. Using many dipole
• c. Using many reflector
• d. All of these

153. It is a measure of how much the antenna concentrates its transmitted microwave power in a given direction

• a. Beamwidth
• b. Polarization
• c. Bandwidth
• d. Gain

154. The angle where the transmitted power has dropped by from the maximum power in the direction at which the antenna is pointing.

• a. Bandwidth
• b. Polarization
• c. Beamwidth
• d. None of these

155. Orientation of the electric field signal propagated from the antenna.

• a. Directivity
• b. Polarization
• c. Sidelobes
• d. Gain

156. Is not included in the group.

• a. Slot
• b. Horn
• c. Helix
• d. Marconi

157. Radiation from an antenna at other angles than the desired direction.

• a. Antenna direction
• b. Field strength
• c. Sidelobe
• d. Directivity

158. If the antenna is not in the exact dimension/measurement, the impedance of the antenna turns to be:

• a. Capacitive
• b. Resistive
• c. Inductive
• d. a or c

159. Impedance for free space is _______.

• a. 120(pi)
• b. 30(pi)
• c. 180(pi)
• d. None of these

160. An antenna is formed of four array antenna, each of which has a gain of _____ if the total gain of these antenna arrays is 30 dB.

• a. 12 dB
• b. 13 dB
• c. 14 dB
• d. 15 dB

161. ______ of the antenna is the ratio of the radiation resistance to the total resistance of the system.

• a. Gain
• b. Directivity
• c. Efficiency
• d. None of these

162. The major lobes of the directive pattern are those in which the radiation is _______.

• a. Minimum
• b. Maximum
• c. Same
• d. None of these

163. Is one supplied power from the transmitter, usually through a transmission line.

• a. Parasitic element
• b. Driven element
• c. Director element
• d. Reflector element

164. Is one which the principal direction of the radiation is perpendicular to the axis of array.

• a. Broadside array
• b. End-fire array
• c. Phased array
• d. Array antenna

165. Front-to-back ratio is the ratio of the forward power and the ________.

• a. Maximum power
• b. Optimum power
• c. Minimum power
• d. Backward power

166. ________ is elective means to generate circular polarization.

• a. Folded antenna
• b. Marconi antenna
• c. Helix antenna
• d. Any antenna

167. Ranges of frequencies the antenna will radiate effectively.

• a. Beamwidth
• b. Bandwidth
• c. Gain
• d. Directivity

168. Is used to increase the current at the base of the antenna, and also to make the current distribution more uniform.

• a. Amplifier
• b. Top loading
• c. Booster
• d. None of these

169. _________ is a network composed of reactances and transformers, which provide impedance matching.

• a. Circulator
• b. Antenna coupler
• c. Matching section
• d. None of these

170. Consisting of grouped radiations or elements.

• a. Turnstile antenna
• b. Antenna array
• c. Phase array
• d. Half-wave dipole

171. The design ratio of the log-periodic antenna must be _____.

• a. Equal to zero
• b. Greater than 1
• c. Less than 1
• d. Unity

172. For low and medium frequency antennas which are mounted vertically from the earth’s surface, the effective length is referred to as __________.

• a. Actual length
• b. Effective height
• c. Actual height
• d. None of these

173. The main difference between half-wave and folded dipole is the __________.

• a. Length
• b. Radiation resistance
• c. Transmission line
• d. None of these

174. A wire several wavelengths in length that is suspended at some height above the earth.

• a. Wire antennas
• b. Long wire antennas
• c. Short wire antennas
• d. Rhombic antennas

175. Consist of two half-wave dipoles placed at right angles to each other and fed 90^o out of phase with each other.

• a. Long wire antennas
• b. Turnstile antennas
• c. Vertical antennas
• d. Rhombic antennas

176. Directivity higher than that obtained with uniform phase.

• a. Super gain
• b. High gain
• c. Medium gain
• d. Low gain

177. A parabolic dish antenna has a diameter of 3m and operates at 46 Hz. Calculate the aperture.

• a. 3.5 square meters
• b. 4.59 square meters
• c. 2.7 square meters
• d. 1.2 square meters

178. If the radiation resistance is 36 ohms, what must be the antenna length?

• a. Half-wavelength long
• b. One wavelength long
• c. Quarter-wavelength long
• d. Any of these

179. If the antenna is receiving of 10^-12 v/m of electric field, magnetic field of 3.2 x 10^-3 A/m at a 5 sq. m absorbing area, what is the power received?

• a. 0.2561 pW
• b. 0.72 pW
• c. 0.016 pW
• d. 0.0012 pW

180. The case where the electric field lies in a plane parallel to the earth surface.

• a. Vertical polarization
• b. Horizontal polarization
• c. Circular polarization
• d. None o f these

181. It is known as a single directive antenna.

• a. Corner director
• b. Corner dipole
• c. Corner reflector
• d. Yagi antenna

182. The presence of dielectric other than air ________ the velocity of light.

• a. Increase
• b. Decrease
• c. Same
• d. Secret

183. The fact that the second wire of the folded dipole is folded makes the current on the two conductors of the antenna flow in the _______ direction.

• a. Same
• b. Opposite
• c. No
• d. None of these

184. A closed circuit antenna is also called __________.

• a. Helix antenna
• b. Discone antenna
• c. Loop antenna
• d. None of these

185. The omega match is slightly modified from the ___________.

• a. T match
• b. Gamma match
• c. Delta match
• d. None of these

186. A dish antenna has a diameter of 2m and operates at 46 Hz, find the antenna gain at 65% efficiency.

• a. 3422.6
• b. 3.26 dB
• c. 12.3 dB
• d. 4266.67

187. What is the approximate effective length of an antenna at 10 MHz

• a. 2.65 m
• b. 9.55 m
• c. 4.62 m
• d. 8.6 m

188. Calculate effective absorbing area operating at 106 Hz for a standard half-wave dipole.

• a. 0.265 mm²
• b. 0.1175 mm²
• c. 1.26 mm²
• d. 2.3 mm²

189. The variation of the slot antenna is _________.

• a. Isotropic antenna
• b. Notch antenna
• c. Lenz antenna
• d. Horn antenna

190. A point where the power field strength is zero.

• a. Minimum
• b. Maximum
• c. Lobe
• d. Null

191. An area of radiation which exist between adjacent nulls.

• a. Minimum
• b. Maximum
• c. Lobe
• d. Nulls

192. The property of an antenna that causes it to receive signal better from one direction than from another.

• a. Gain
• b. Directivity
• c. Dipole
• d. Reflector

193. The 70.7% point on the polar graph is known as the _________ point and represent the point of maximum width of the lobe

• a. Full power
• b. Half-power
• c. Quarter point
• d. Maximum point

194. A transmitting antenna has a gain of 10 and a power input of 60 watts. What is the effective radiated power?

• a. 6 kW
• b. 60 kW
• c. 0.6 kW
• d. 600 kW

195. Marconi antenna is used in many types of mobile communications unit because it allows transmission and receptions in _________.

• a. One direction
• b. Two direction
• c. More direction
• d. All direction

196. Used only to a small degree in the VHF band because of its large size requirements

• a. Vee antenna
• b. Long antenna
• c. Rhombic antenna
• d. Marconi antenna

197. A resistance which accounts for the energy dissipated in the form of heat

• a. Ohmic resistance
• b. Surge resistance
• c. Radiation resistance
• d. None of these

198. Antenna array having one active dipole element and two or more parasitic element is known as _______.

• a. Marconi
• b. Horizontal antenna
• c. Ground antenna
• d. Yagi-Uda antenna

199. This antenna is a monopole in that it uses a half-wavelength radiator, but is fed at a voltage node rather than current node.

• a. Voltage antenna
• b. Zepp antenna
• c. Quartz antenna
• d. Xylene antenna

200. Vertical antenna like those used in the AM broadcast and lower frequency armature band rely heavily upon a good __________ for maximum coverage.

• a. Insulation
• b. Ground system
• c. Gain
• d. Directivity

Complete List of MCQs in Communications Engineering per topic

Series of Multiple Choice Questions in Electronics Systems and Technologies

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