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Two transmission lines each having an impedance of 200 ╬й is separated by a cable like, for zero reflection, the impedance of cable should be
100 ╬й
200 ╬й
400 ╬й
600 ╬й
200 ╬й
For zero reflection at an interface between two transmission lines, the characteristic impedance of the lines must be perfectly matched. When a cable is connected between two lines of the same impedance, it must have an identical characteristic impedance to ensure that the reflection coefficient becomes zero.
For zero reflection at an interface between two transmission lines, the characteristic impedance of the lines must be perfectly matched. When a cable is connected between two lines of the same impedance, it must have an identical characteristic impedance to ensure that the reflection coefficient becomes zero.
╬У=ZLтАЛ+Z0тАЛZLтАЛтИТZ0тАЛтАЛ тАФ Reflection Coefficient definition
Z0тАЛ=G+j╧ЙCR+j╧ЙLтАЛтАЛ тАФ Characteristic Impedance of a transmission line
The reflection coefficient (╬У) at the junction of two transmission lines with impedances Z1тАЛ and Z2тАЛ is given by ╬У=Z2тАЛ+Z1тАЛZ2тАЛтИТZ1тАЛтАЛ. For zero reflection (perfect impedance matching), ╬У must equal zero, which implies Z2тАЛ=Z1тАЛ.
Maximum power transfer occurs when source impedance equals load impedance (matched condition).
Reflection is caused by an impedance discontinuity along the transmission path.
A matched line (╬У=0) ensures that the entire incident wave is absorbed by the load.
Transmission line transients are minimized when surge impedance loading is maintained.
Eliminates standing waves on the line.
Prevents signal distortion and loss of energy due to reflections.
Hard to maintain perfectly in long-distance power systems due to varying load conditions.
Requires precise cable manufacturing tolerances.
High-voltage DC (HVDC) transmission links.
Telecommunication coaxial cable networks.
RF signal propagation in high-frequency circuits.
The surge impedance or characteristic impedance Z0тАЛ is purely resistive for lossless lines (R=0,G=0).
If ZcableтАЛюАа=200╬й, the reflection coefficient would be non-zero, resulting in traveling waves reflecting back toward the source.
B is correct тАФ For zero reflection at the junction, the characteristic impedance of the intervening cable must match the impedance of the connected transmission lines, which is 200 ╬й.
Always remember that in transient analysis, reflection occurs whenever there is a change in the medium's impedance; matching the impedance eliminates these reflections entirely.