My company has just obtained the 8753D network analyzer, and I am still new at it.
I am attempting to test for insertion loss.
Test Requirements:
Insertion loss per 100ft
N-type to N-type
Frequency Range: 1GHz
Max Loss: 14dB
Network Analyzer Set up:
Measure: S21 Transmit
Format: Log Mag
Scale Ref: Auto Scale
Center: 1GHz
Span: 500MHz
Marker: 1GHz
AVG: Averaging ON Smoothing ON
Problem: Most cables I test result in a -dB value which I am assuming is LOSS. However, when testing a shorter cable, e.g. 18inches,the result is a positive value(e.g. .2378dB). Why is this ? am I interpreting this incorrectly or am I setting something up wrong?
I am attempting to test for insertion loss.
Test Requirements:
Insertion loss per 100ft
N-type to N-type
Frequency Range: 1GHz
Max Loss: 14dB
Network Analyzer Set up:
Measure: S21 Transmit
Format: Log Mag
Scale Ref: Auto Scale
Center: 1GHz
Span: 500MHz
Marker: 1GHz
AVG: Averaging ON Smoothing ON
Problem: Most cables I test result in a -dB value which I am assuming is LOSS. However, when testing a shorter cable, e.g. 18inches,the result is a positive value(e.g. .2378dB). Why is this ? am I interpreting this incorrectly or am I setting something up wrong?
You want to be sure to perform a calibration, a normalization or thru cal at a minimum. A two-port cal would be even better, especially if your cable has poor match.
Also, reduce the IFBW to reduce the trace noise, or use averaging. A positive value could simply be noise, or measurement error, but 0.23 is not that small.
Afsi