Description : A coaxial cable has 7dB of reflected power when the input is 5 watts. What is the output of the transmission line? A. 5 watts B. 2.5 watts C. 1.25 watts D. 1 watt
Last Answer : D. 1 watt
Description : A transmission line of unknown impedance is terminated with two different resistances, and an SWR is measured each time. With a 75 Ω termination, the SWR measures 1.5. With a 300 Ω termination, it measures 2.67. What is the impedance of the line? A. 100 Ω B. 212 Ω C. 300 Ω D. 112 Ω
Last Answer : D. 112 Ω
Description : What type of balun (balanced-to-unbalanced) is used in high frequency applications? A. Transformer type balun B. A specially configured coaxial transmission line C. A specially configured parallel-wire line D. A λ/2 transformer balun
Last Answer : B. A specially configured coaxial transmission line
Description : What is the characteristic impedance of a coaxial line with the following data: inner diameter = 0.2 in., center conductor diameter = 0.06 in., insulation = Teflon. A. 200Ω B. 75Ω C. 50Ω D. 150Ω
Last Answer : C. 50Ω
Description : Termination means A. result of disconnecting a line from a transmitter B. result of cutting both ends of a conductor C. looking back impedance of a line with no load D. load connected to the output end of a transmission line
Last Answer : D. load connected to the output end of a transmission line
Description : Which of the following is considered the most frequently used transmission line? A. Two-wire open line B. Twin lead C. Rigid coaxial line D. Flexible coaxial line
Last Answer : D. Flexible coaxial line
Description : What would be the physical length of a tpical coaxial transmission line that is electrically one-quarter wavelength long at 14.1 MHz? A. 20 meters B. 3.51 meters C. 2.33 meters D. 0.25 meter
Last Answer : B. 3.51 meters
Description : Why is the physical length of a coaxial cable transmission line shorter than its electrical length? A. Skin effect is less pronounced in the coaxial cable B. RF energy moves slower along the ... higher in the parallel feed line D. The characteristic impedance is higher in the parallel feed line
Last Answer : B. RF energy moves slower along the coaxial cable
Description : What is the meaning of the term velocity factor of a transmission line? A. The ratio of the characteristic impedance of the line to the terminating impedance B. The index of shielding for coaxial ... The velocity of the wave on the transmission line divided by the velocity of light in a vacuum.
Last Answer : D. The velocity of the wave on the transmission line divided by the velocity of light in a vacuum.
Description : A transmission line consisting of two conductors that have equal resistance per unit length. A. Unbalanced line B. Open-wire line C. Balanced line D. Coaxial line
Last Answer : C. Balanced line
Description : What is the meaning of the term velocity factor of a transmission line? A. The index of shielding for coaxial cable B. The velocity of the wave on the transmission line multiplied by the velocity of ... The velocity of the wave on the transmission line divided by the velocity of light in a vacuum
Last Answer : D. The velocity of the wave on the transmission line divided by the velocity of light in a vacuum
Description : Best choice of transmission line component to couple a coaxial line to a parallel-wire line A. Shorting B. Balun C. Slotted line D. Directional coupler
Last Answer : B. Balun
Description : Characteristics impedance of a transmission line is the impedance measured at the ___________ when its length is infinite. A. input B. shorted end of the line C. output D. midsection
Last Answer : A. input
Description : When a transmission line uses ground return, it is called a/an __________ line. A. ungrounded B. balanced C. unbalanced D. grounded
Last Answer : C. unbalanced
Description : What material is most often used for the outer covering of coaxial cables? A. PVC B. Teflon C. PE D. Polystyrene
Last Answer : A. PVC
Description : A current `i` ampere flows along the inner conductor of a coaxial cable and returns along the outer conductor fo the cable, then the magnetic inductio
Last Answer : A current `i` ampere flows along the inner conductor of a coaxial cable and returns along the outer conductor fo the ... D. `(mu_(0))/(2pi)(2pii)/(r)`
Description : In a coaxial, straight cable, the central conductor and the outer conductor carry equal currents in opposite directions. The magnetic field is zero.
Last Answer : In a coaxial, straight cable, the central conductor and the outer conductor carry equal currents ... outer conductor D. in between the two conductors
Description : What is the major factor that makes coaxial cable less susceptible to noisethan twisted-pair cable? A) inner conductor B) diameterof cable C) outer conductor D) insulating material
Last Answer : outer conductor
Description : Which of the following best describes a dip-meter? A. An SWR meter B. A counter C. A variable LC oscillator with metered feedback current D. A field strength meter
Last Answer : C. A variable LC oscillator with metered feedback current
Description : Best described a dip-meter. A. A variable LC oscillator with metered feedback current B. An SWR meter C. A counter D. A field strength meter
Last Answer : A. A variable LC oscillator with metered feedback current
Description : Which tester is used to measure SWR? A. Spectrum analyzer B. Multimeter C. Reflectometer D. Oscilloscope
Last Answer : C. Reflectometer
Description : The presence of standing waves on a transmission line is the result of A. a high level of attenuation on the line. B. terminating the line by a resistive load equal in value to the surge impedance ... input power to below its critical level. D. an impedance mismatch between the load and the line.
Last Answer : D. an impedance mismatch between the load and the line.
Description : What is the input impedance of a transmission line if its characteristic impedance is 300 Ω and the load is 600 Ω? Assume a quarter wavelength section only. A. 150 kΩ B. 150 mΩ C. 150 Ω D. 2 Ω
Last Answer : C. 150 Ω
Description : The minimum impedance of a 75 ohm transmission line with a SWR of 2.5 is a) 100 b) 50 c) 25 d) 30
Last Answer : d) 30
Description : The maximum impedance of a 50 ohm transmission line with SWR of 3 is a) 50/3 b) 3/50 c) 150 d) 450
Last Answer : c) 150
Description : A load of 200 ohm is used to match 300 ohm transmission line to achieve SWR=1. Find out the required characteristic impedance of a quarter of a quarter wave transformer connected directly to the load.
Last Answer : Solution :
Description : a) For a transmission line, Find SWR and reflection coefficient R if, i. There is no reflected voltage. ii. Reflected voltage and incident voltage is equal. iii. If reflected voltage=20V and incident voltage=10V. iv. If reflected voltage=10V and incident voltage =20V.
Last Answer : reflection coefficient R=Vr/Vi i. There is no reflected voltage. i.e,Vr=0 R=0 SWR= 1+R/1-R=1 ii. Reflected voltage and incident voltage is equal. Vr=Vi; R=1 SWR= 1+R/1-R=1+1/1-1=infinity iii. If reflected ... and incident voltage =20V. Vr=10 and Vi=20 R=10/20=0.5 SWR= 1+R/1-R=1+.5/1-.5=3
Description : For a transmission line, the incident voltage. Ei = 6V and Er =2V ,Calculate: (i) Reflection Coefficient (ii) SWR
Last Answer : Reflection Coefficient(K) = Er / Ei = 2V / 6V K = 0.333 SWR = 1+K / 1- K = 1+0.333 / 1-0.333 = 1.333 / 0.667 SWR= 1.998
Description : What determines the velocity factor in a transmission line? A. The termination impedance B. The line length C. Dielectrics in the line D. The center conductor resistivity
Last Answer : C. Dielectrics in the line
Description : What determines the velocity factor in transmission line? A. The center conductor resistivity B. Dielectrics in the line C. The termination impedance D. The line length
Last Answer : B. Dielectrics in the line
Description : ECE Board Exam March 1996 The characteristics impedance of a transmission line does not depend upon its ________. A. conductor spacing B. conductor diameter C. length D. conductor radius
Last Answer : C. length
Description : Which of the following characterizes a properly terminated transmission line? A. The line loss is minimum. B. The standing wave ratio is minimum. C. The input impedance is twice the load impedance. D. The standing wave ratio is one.
Last Answer : D. The standing wave ratio is one.
Description : What do you call a cable consisting of twisted pairs of conductors, each separately insulated? A. Microstrip line B. Strip line C. Quad D. Coaxial cable
Last Answer : C. Quad
Description : Which of the following is not a bounded medium? A. Coaxial line B. Two-wire line C. Waveguide D. Free space
Last Answer : D. Free space
Description : What medium is used by IBM token ring network that operates at either 4 Mbps or 16 Mbps? A. Twisted pair B. Coaxial cable C. Fiber-optic D. Parallel-wire line
Last Answer : A. Twisted pair
Description : What line has a typical velocity factor of about 0.8? A. Shielded pair B. Flexible coaxial C. Twin-lead D. Open-wire line
Last Answer : C. Twin-lead
Description : To couple a coaxial line to parallel line, it is better to use a ______. A. Slotted line B. Quarter-wave transformer C. Directional Coupler D. Balun
Last Answer : D. Balun
Description : To connect coaxial line to a parallel-wire _________ is the best to use. A. directional coupler B. quarter-wave transformer C. balun D. slotted line
Last Answer : C. balun
Description : What is meant by antenna gain? A. The final amplifier gain minus the transmission line losses (including any phasing lines present) B. The ratio of the amount of power produced by the antenna ... D. The numeric ratio relating the radiated signal strength of an antenna to that of another antenna
Last Answer : D. The numeric ratio relating the radiated signal strength of an antenna to that of another antenna
Description : ECE Board Exam March 1996 What is the transmission rate of a system for transmitting the output of a microcomputer to a line printer operating at a speed of 30 lines/minute? Assume that the line printer has 8 bits ... and prints out 80 characters/line. A. 800 bps B. 400 bps C. 320 bps D. 640 bps
Last Answer : C. 320 bps
Description : What is driven element? A. Always the rearmost element B. Always the forward most element C. The element fed by the transmission line D. The element connected to the rotator
Last Answer : C. The element fed by the transmission line
Description : What is a driven element of an antenna? A. Always the rearmost element B. Always the forwardmost element C. The element fed by the transmission line D. The element connected to the rotator
Description : What causes the current-carrying area at the center conductor of a coaxial line to be restricted to a small layer at the surface?
Last Answer : Skin effect.
Description : Transmission lines are either balanced or unbalanced with respect to _________. A. negative terminal B. input C. ground D. positive terminal
Last Answer : C. ground
Description : ____ system transmits frequency-division-multiplexed voice band signals over a coaxial cable for distances up to 4000 miles. A. T carrier B. X carrier C. L carrier D. F carrier
Last Answer : C. L carrier
Description : What is the velocity factor for non-foam dielectric 50 or 75 ohm flexible coaxial cable such as RG 8, 11, 58 and 59? A. 2.70 B. 0.66 C. 0.30 D. 0.10
Last Answer : B. 0.66
Description : An RG-11/U foam coaxial cable has a maximum voltage standing wave of 52 V and a minimum voltage of 17 V. Find the value of the resistive load. A. 24.59Ω B. Either A or C C. 228.75Ω D. Neither A nor C
Last Answer : B. Either A or C
Description : What is the time delay introduced by a 75-ft coaxial cable with a dielectric constant of 2.3? A. 1.54 ns B. 11.5 ns C. 115.6 ns D. 1156 ns
Last Answer : C. 115.6 ns
Description : What is the velocity factor of coaxial cable with a characteristic impedance of 50Ω and capacitance of 30pF/ft and inductance of 75 nH/ft? A. 0.58 B.0.68 C. 0.98 D. 0.81
Last Answer : B.0.68
Description : What is the typical velocity factor of coaxial cables? A. 0.6 to 0.8 B. 0.3 to 0.5 C. 0.5 to 0.9 D. 0.4 to 0.6
Last Answer : A. 0.6 to 0.8