Online Questions and Answers Topic Outline
- MCQs in Transmission System
- MCQs in Transmission Medium
- MCQs in Velocity and Line Wavelength
- MCQs in Characteristics Impedance
- MCQs in Primary Line Constants and Propagation Constants
- MCQs in Standing Waves
- MCQs in Voltage Standing Wave Ratio
- MCQs in Telephone Lines and Cables
- MCQs in Wave Guides
- MCQs in Balanced and Unbalanced Lines
- MCQs in Twisted pair wire, Coaxial Cable
- MCQs in Decibel
- MCQs in Signal and Noise Fundamentals
MCQs in Transmission Fundamentals Series
Following is the list of multiple choice questions in this brand new series:
Continue Practice Exam Test Questions Part III of the Series
101. The frequency range over which a rectangular waveguide is excited in the dominant mode is limited to
- a. the difference between the frequency for which the reflection angle is 90o and the frequency for which angle is zero
- b. the difference between the frequency for which the free-space wavelength is equal to the cutoff value and the frequency for which the free-space wavelength is equal to the guide wavelength
- c. the difference between the frequency at which the cutoff wavelength is twice the narrow dimension
- d. none of these
102. If a rectangular waveguide is to be excited in the dominant mode, the E-probe should be inserted
- a. at the sealed end
- b. at a distance of one quarter –wavelength from the sealed end
- c. at a distance of one-half wavelength from the sealed end
- d. at a distance of three-quarters of a wavelength from the sealed end
103. A quarter-wave line is connected to an RF generator and is shorted out at the far end. What is the input impedance to the line generator?
- a. A low value of resistance
- b. A high value of resistance
- c. A capacitive resistance which is equal in the value to the line’s surge impedance
- d. An inductive resistance which is equal to the value to the line’s surge impedance
104. If the SWR on a transmission line has a high value, the reason could be
- a. an impedance mismatch between the line and the load
- b. that the line is non-resonant
- c. a reflection coefficient of zero at the load
- d. that the load is matched to the line
105. If a quarter-wave transmission line is shorted at one end
- a. there is minimum current at the shorted end
- b. the line behaves as a parallel-tuned circuit in relation to the generator
- c. the line behaves as a series-tuned circuit in relation to the generator
- d. there is a minimum voltage at the shorted end
106. A 50-ohm transmission line is feeding an antenna which represents a 50 ohm resistive load. To shorten the line, the length must be
- a. any convenient value
- b. an odd multiple of three quarters of a wavelength
- c. an odd multiple of half a wavelength
- d. an even multiple of a quarter of a wavelength
107. The outer conductor of the coaxial cable is usually grounded
- a. at the beginning and at the end of the cable
- b. only at the beginning of the cable and only at the end of the cable
- c. only at the end of the cable
- d. at the middle of the cable
108. A feature of an infinite transmission line is that
- a. its input impedance at the generator is equal to the line’s surge impedance
- b. its phase velocity is greater than the velocity of light
- c. no RF current will be drawn from the generator
- d. the impedance varies at different positions on the line
109. When the surge impedance of a line is matched to a load, the line will
- a. transfer maximum current to the load
- b. transfer maximum voltage to the load
- c. transfer maximum power to the load
- d. have a VSWR equal to zero
110. A lossless line is terminated by a resistive load which is not equal to the surge impedance. If the value of the reflection coefficient is 0.5, the VSWR is
- a. 2
- b. 3
- c. 4
- d. 15
111. Ratio of the mismatch between the antenna and the transmitter power.
- a. Standing wave pattern
- b. Reflection coefficient
- c. SWR
- d. Index of refraction
112. Emission designation for a facsimile.
- a. H3E and A4E
- b. R3E and A4E
- c. F4E and J3E
- d. F3C and A3E
113. Commonly used telephone wire.
- a. AWG #19
- b. AWG #18
- c. AWG #30
- d. AWG #33
114. What is the distance traveled by a wave in the time of one cycle?
- a. Frequency
- b. Hop
- c. Wavelength
- d. Crest
115. The velocity factor is inversely proportional with respect to the _______.
- a. square of the dielectric constant
- b. square root of the dielectric constant
- c. dielectric current
- d. square root of refractive index
116. ________ is a hollow structure that has no center conductor but allows waves to propagate down its length.
- a. Waveguide
- b. Hybrid
- c. Pipe
- d. Directional coupler
117. To connect a coaxial line to a parallel wire line, _______ is used.
- a. hybrid circuit
- b. balun
- c. directional coupler
- d. quarter-wave transformer matching circuit
118. What length for which the input power has been halved for a transmission line with an attenuation of 6 dB/km?
- a. 1.5 km
- b. 0.5 km
- c. 63 km
- d. 2 km
119. Ina waveguide, _______ is a specific configuration of electric and magnetic fields that allows a wave to propagate.
- a. set-up
- b. coupler
- c. channel
- d. mode
120. A rectangular waveguide has dimensions of 3 cm x 5 cm. What is the dominant mode cut-off frequency?
- a. 2 GHz
- b. 3 GHz
- c. 2.5 GHz
- d. 3.5 GHZ
121. ________ are transmission lines which can convey electromagnetic waves only in higher order modes?
- a. Coaxial cables
- b. Twisted pairs of telephone wire
- c. Power cables
- d. Waveguides
122. The amount of uncertainty in a system of symbols is also called
- a. bandwidth
- b. loss
- c. entropy
- d. quantum
123. The twists in twisted wire pairs
- a. reduced electromagnetic interference
- b. occur at a 30-degree angle
- c. eliminate loading
- d. were removed due to cost
124. An example of a bounded medium is
- a. coaxial cable
- b. waveguide
- c. fiber-optic cable
- d. all of the above
125. Loading means the addition of
- a. resistor
- b. capacitor
- c. bullet
- d. inductance
126. What is the most commonly used transmission line for high frequency application?
- a. Two-wire balance line
- b. Single wire
- c. Three-wire line
- d. Coaxial
127. The characteristic impedance of a transmission line does not depend upon its
- a. length
- b. conductor diameter
- c. conductor spacing
- d. dielectric material
128. One of the following is not a common transmission line impedance.
- a. 50 ohms
- b. 75 ohms
- c. 120 ohms
- d. 300 ohms
129. For maximum absorption of power at the antenna, the relationship between the characteristic impedance of the line Zoand the load impedance ZL should be
- a. Zo = ZL
- b. Zo > ZL
- c. Zo < ZL
- d. Zo = 0
130. The mismatch between antenna and transmission line impedance cannot be corrected for by
- a. using LC matcging network
- b. adjusting antenna length
- c. using a balun
- d. adjusting the length of transmission line
131. ________ is a pattern of voltage and current variations along a transmission line not terminated in its characteristic impedance.
- a. An electric field
- b. Radio waves
- c. Standing waves
- d. A magnetic field
132. Which is the desirable SWR on a transmission line?
- a. 0
- b. 1
- c. 2
- d. Infinity
133. A 50ohm coax is connected to a 73-ohm antenna. What is the SWR?
- a. 0.685
- b. 1
- c. 1.46
- d. 2.92
134. What is the most desirable reflection coefficient?
- a. 0
- b. 0.5
- c. 1
- d. Infinity
135. What is the ratio expressing the percentage of incident voltage reflected on a transmission line?
- a. Velocity factor
- b. Standing-wave ratio
- c. Reflection coefficient
- d. Line efficiency
136. The minimum voltage along a transmission line is 260 V, while the maximum is 390 V, the SWR is
- a. 0.67
- b. 1.0
- c. 1.2
- d. 1.5
137. One meter is one wavelength at a frequency of
- a. 150 MHz
- b. 164 MHz
- c. 300 MHz
- d. 328 MHz
138. At very high frequencies, transmission lines act as
- a. Tuned circuits
- b. Antennas
- c. Insulators
- d. Resistors
139. A shorted quarter-wave line at the operating frequency acts like a/an
- a. Capacitor
- b. Inductor
- c. Series resonant circuit
- d. Parallel resonant circuit
140. A shorted half-wave line at the operating frequency acts like a/an
- a. Capacitor
- b. Inductor
- c. Series resonant circuit
- d. Parallel resonant circuit
141. A medium least susceptible to noise?
- a. Shielded pair
- b. Twisted pair
- c. Fiber-optic
- d. Coaxial
142. A medium most widely used in LANs?
- a. Parallel-wire line
- b. Twisted pair
- c. Fiber-optic cable
- d. Coaxial
143. The most commonly used transmission line in television system.
- a. Parallel-wire line
- b. Coaxial cable
- c. Waveguide
- d. Open-wire ceramic supports
144. The impedance of a TV transmission line depends on several factors. Which is not one of those factors?
- a. Diameter
- b. Length of the wire
- c. Dielectric material
- d. Separation between conductors
145. DC blocks are used in coaxial transmission line for the purpose of
- a. passing DC while blocking AC
- b. passing AC voltage but prevent DC
- c. preventing AC voltage from reaching the pre-amplifier
- d. preventing AC power supply voltage from being shorted by a balun or band splitter
146. _______ is a type of interference caused by off-air TV channels 2 and 4, plus a satellite dish operating on channel 3.
- a. Adjacent channel interference
- b. Ghost
- c. Co-channel interference
- d. Crosstalk
147. Dithering (in TVRO communication) is a process of
- a. Reducing the effect of noise on the TVRO video signal
- b. Centering the video fine tuning on TVRO channels
- c. Moving the feedhorn rotor to the precise angle
- d. Moving the actuator exactly onto the desired satellite beam
148. A network that has an input of 75dB and an output of 35dB. The loss of the network is
- a. -40db
- b. 40db
- c. 40dBm
- d. -4dBm
149. Important useful quantities describing waveforms.
- a. Time and frequency
- b. Voltage and current
- c. Frequency and voltage
- d. Power and frequency
150. Halving the power means
- a. 6-dB gain
- b. 3-dB loss
- c. 3-dB gain
- d. 6-dB loss
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