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# MCQ in Microwave Communications Part 3 | ECE Board Exam

This is the Multiples Choice Questions Part 3 of the Series in Microwave Communications 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 Basic Principles of Microwave Communications
• MCQ in Electro-Optics
• MCQ in Photonics
• MCQ in Optoelectronics
• MCQ in Electromagnetics
• MCQ in Avionics, Aerospace, Navigational and Military Applications
• MCQ in Medical Electronics
• MCQ in Cybernetics
• MCQ in Biometrics

#### Continue Practice Exam Test Questions Part 3 of the Series

101. The free space attenuation between two microwave antennas 40 km apart operating at 8 GHz is

A. 146.7 dB

B. 142.55 dB

C. 82.5 dB

D. 86.7 dB

Solution:

102. An active microwave radio repeater that can provide drops and inserts.

B. Baseband repeater

C. IF repeater

D. RF repeater

Solution:

103. If the correction factor k equals 4/3 of the earthโs curvature, the microwave beam would have a curvature that is ___________ than that of the earth.

A. More

B. Less

C. Equal

D. Not related

Solution:

104. The optimum clearance from an obstacle in an microwave system is accepted as __________ of the first fresnel zone radius.

A. 0.6

B. 0.5

C. 0.9

D. 1.5

Solution:

105. The microwave beam curves the same than that of the earth when the value of the correction factor k equals

A. 0

B. 4/3

C. 2/3

D. Infinity

Solution:

106. The time from the transmission of a radar pulse to its reception is 0.12 ms. The distance to the target is how many nautical miles?

A. 4.85 nmi

B. 9.7 nmi

C. 11.2 nmi

D. 18.4 nmi

Solution:

107. The ability of a radar to determine the bearing to a target depends upon the

A. Antenna directivity

B. Speed of light

C. Speed of the target

D. Frequency of the signal

Solution:

108. The pulse duration of a radar signal is 699ns. The PRF is 185 pulses per second. The duty cycle is

A. 0.216 %

B. 0.130 %

C. 0.013 %

D. 0.407 %

Solution:

109. The Doppler effect allows which characteristics of a target to be measured?

A. Distance

B. Azimuth

C. Altitude

D. Speed

Solution:

110. The Doppler effect is a change in what signal characteristics produced by relative motion between the radar set and a target?

A. Amplitude

B. Phase

C. Frequency

D. Duty cycle

Solution:

111. The most widely used radar transmitter component is a

A. Klystron

B. Magnetron

C. TWT

D. Power transistor

Solution:

A. GaAs FET

B. Magnetron

C. Gunn diode

D. Klystron

Solution:

113. What component in a duplexer protects the receiver from the higher transmitter output?

A. Waveguide

B. Bandpass filter

C. Notch filter

D. Spark gap

Solution:

114. Most radar antennas use a

A. Dipole

C. Horn and parabolic reflector

D. Collinear array

Solution:

115. The most common radar display is the

A. A scan

B. Color CRT

C. LCD

D. PPI

Solution:

116. A radar antenna using multiple diploes or slot antennas in a matrix with variable phase shifters is called a/an

A. A scan

B. Phased array

D. Circulator polarized array

Solution:

117. Which of the following is a typical radar operating frequency?

A. 60 MHz

B. 450 MHz

C. 900 MHz

D. 10 GHz

Solution:

118. A microwave system requires the use of repeaters when

A. The intervening terrain is favorable

B. The distances involve are grater

C. The required reliability is meet

Solution:

119. Are transmission lines which convey electromagnetic waves in highest frequencies

A. Twister pair of telephone wires

B. Waveguides

C. Power lines

D. Coaxial cables

Solution:

120. A microwave band of 10.9 to 36. GHz is considered as

A. C-band

B. X-band

C. Q-band

D. K-band

Solution:

121. A microwave communications system space loss calculation formula.

A. 94.2 + 20 log f + 20 log d

B. 92.4 + 20 log f + 20 log d

C. 94.2 + 10 log f + 20 log d

D. 92.3 + 10 log f + 20 log d

Solution:

122. A waveguide is also a

A. Low pass filter

B. High pass filter

C. Band pass filter

D. Band stop filter

Solution:

123. A method of diversity reception where the signal is transmitted on two difference frequencies over the same path

A. Space diversity

B. Frequency diversity

C. Polarization diversity

D. Wavelength diversity

Solution:

124. A wire used to reduce the skin effect

A. AWG # 14

B. AWG # 15

C. Copper wire

D. Litz wire

Solution:

125. Space diversity transmission means transmitting and receiving on two or more.

A. Different frequencies

B. Antennas operating on two different frequencies

C. Antennas operating on the same frequencies

D. Identical frequencies

Solution:

126. The best system configuration to overcome multipath fading of microwave system over the water

A. Space diversity

B. Frequency diversity

C. Polarization diversity

D. Wavelength diversity

Solution:

127. When the value of k increases, the effective result is _______ of the equivalent curvature

A. Flattening

B. Bulging

C. Sharp curvature

D. All of these

Solution:

128. A traveling wave tube consists of

A. Electron gun, helix and repeller

B. Electron gun, helix and collector

C. Electron gun, repeller and collector

D. Buncher cavity and catcher cavity

Solution:

129. Advantage of periscope antenna in microwave

A. Reduce tower height

B. Minimize interference to and from other neighboring stations

C. Shorten waveguide length

D. Easy to install

Solution:

130. What is the cut-off frequency of a waveguide?

A. The highest frequency the waveguide operates

B. The lowest frequency the waveguide operates

C. The same as the operating frequency

D. The only frequency the waveguide operates.

Solution:

131. When the clearance above the obstruction is equal to the radii of even fresnel zones at the point of reflection. The RSL is

A. Increased

B. Decreased

C. Constant

D. Above threshold

Solution:

132. What is the wavelength of a wave in a waveguide?

A. Greater than in free space

B. Depends only on the waveguide dimensions and the free-space wavelength

C. Inversely proportional to the phase velocity

D. Inversely proportional to the group velocity

Solution:

133. The CCIR hypothetical reference circuit covering a distance of 25000 km consists of a total of how many hops?

A. 5

B. 10

C. 24

D. 54

Solution:

134. Water causes more attenuation particularly on what frequency?

A. 20 GHz

B. 63 GHz

C. 183 GHz

D. 202 GHz

Solution:

135. At what frequency does oxygen cause excessive attenuation?

A. 60 GHz

B. 50 GHz

C. 40 GHz

D. 30 GHz

Solution:

136. Which of the following is an atmospheric attenuation?

A. Attenuation due to water vapor and oxygen

B. Attenuation due to mist and fog

C. Attenuation due to other gases

D. Attenuation due to rain.

Solution:

137. A microwave system operating at the 6 GHz band is carrying 600 voice channels. What is the noise loading power in dBmO?

A. 12.78

B. 26.78

C. 27.78

D. 10.25

Solution:

138. _________ is a microwave link between the down-town terminal and another out of town terminal.

A. STL

D. Terrestrial

Solution:

139. Attenuator is used in the traveling wave tube to

A. Prevent oscillation

B. Increase gain

C. Prevent saturation

D. All of these

Solution:

140. Is a method of diversity reception applied to reflective path to reduce fading.

A. Frequency diversity

B. Space diversity

C. Polarization diversity

D. Wavelength diversity

Solution:

141. What is the effective earthโs radius used in communications design?

A. 4000 miles

B. K x 4000 miles

C. 5000 miles

D. K x 5280 miles

Solution:

142. IF bandwidth of a radar system is inversely proportional to

A. Pulse width

B. Pulse interval

C. Peak transmit power

D. All of these

Solution:

A. Electronic Air Data Indicator

B. Electronic Altitude and Distance Indicator

C. Electronic Altitude and Director Indicator

D. Electronic Air and Distance Indicator

Solution:

144. Which aircraft navigational system determines the time to station (TTS) or time to go (TTG)?

B. DME

C. Timer

D. ATC

Solution:

145. What frequency does a radio altimeter operate?

A. 33500 kHz

B. 43000 kHz

C. 33500 MHz

D. 43500 MHz

Solution:

146. What inflight system allows passengers to make telephone calls, send faxes, and computer data shop and play computer games, etc.?

A. Inflight Satellite System

B. Terrestrial Flight Telephone System

C. World Airline Entertainment System

D. Satellite Phone

Solution:

A. Audio Direction Findings

B. Automatic Direction Finder

C. Alternate Direction Finder

D. Automatic Distance Finder

Solution:

148. RF carrier of the middle marker is modulated at ____ Hz.

A. 1300

B. 1400

C. 1500

D. 1600

Solution:

149. Which of the following is considered as the major advantage of using a helix traveling wave tube?

A. Cheaper

B. Less noise

C. High power

D. Wide bandwidth

Solution:

Solution:

#### Questions and Answers in Microwave Communications and Principles Series

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

MCQ in Microwave Communications
PART 1: MCQ from Number 1 โ 50                        Answer key: PART 1
PART 2: MCQ from Number 51 โ 100                   Answer key: PART 2
PART 3: MCQ from Number 101 โ 150                 Answer key: PART 3
PART 4: MCQ from Number 151 โ 200                 Answer key: PART 4
PART 5: MCQ from Number 201 โ 250                 Answer key: PART 5
PART 6: MCQ from Number 251 โ 300                 Answer key: PART 6
PART 7: MCQ from Number 301 โ 350                 Answer key: PART 7
PART 8: MCQ from Number 351 โ 400                 Answer key: PART 8
PART 9: MCQs from Number 401 โ 450                 Answer key: PART 9
PART 10: MCQs from Number 451 โ 500                 Answer key: PART 10

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

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