A time-domain reflectometer drives a line made of RG-58 (velocity

PHYSICS · Multi-part · Fermi University Physics · Electricity, Magnetism & Electromagnetism · Electromagnetic waves and their propagation · Electromagnetic waves and their propagation

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Problem

A time-domain reflectometer drives a

50\,\Omega

line made of RG-58 (velocity

v_p = 2.0\times10^8\,\mathrm{m\,s^{-1}}

, as used earlier for this cable) from a source whose output impedance equals

50\,\Omega

. Immediately after the step is launched the near-end voltage settles at

V_s/2

; then,

40\,\mathrm{ns}

after the step is launched, it falls to

V_s/6

and stays there. ((a)) Find the reflection coefficient

\Gamma

of the fault. ((b)) Find the load impedance

Z_L

that produces it. ((c)) Find the distance from the near end to the fault. ((d)) State the standing-wave ratio and the return loss that this fault would show on a network analyser at a frequency where the line looks purely resistive.

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