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transmission line, reflection coefficient of both discontinuous points is 0.333.
During time domain Measure, if reflection coefficient of the first discontinuous point is about 0.333, this is the right case.
Response value of the second discontinuous point is not 0.333 and it can be found from
△
marker that there is an amplitude of
35mU between two responses, this is because that energy reflection caused by the first mismatch makes the incident pulse
amplitude of the second response smaller than unit value 1U.
Fig.8-13 Effect of Screening Caused by Energy Reflection toward Measure
8.5.1.2.
Screening caused by energy absorption
Screening caused by energy absorption happens when measuring loss circuit. In Measure below, an open-circuit device is
terminated to a cable and the Measure result displays the screening caused by energy absorption.
Fig.8-14 Effect of Screening Caused by Energy Absorption toward Measure Result
Marker 1 displays that return loss of open-circuit device is -2.5dB (observed in the format of logarithm amplitude).
Actual return loss of open-circuit device shall be 0dB.
Value of Marker 1 represents the sum of forward and backward pass losses.
8.5.2.
Reflection Measure in Band Pass Mode
Horizontal axis data:
It represents the time used when pulse is transmitted from measuring port and transferred to discontinuous point and then gets
back to measuring port.
Vertical axis data:
With format of logarithm amplitude, it represents return loss (dB).
With format of linear amplitude, it represents reflection coefficient.
