Giga-tronics 8003 - Figure 1-4: Reflection Uncertainty Relative to Directivity; Figure 1-5: Reflection Uncertainty Relative to Source Match; Reflection Measurements

8003 Precision Scalar Analyzer
1-10 Manual 20791, Rev. C, June 2001
1.3.2.2 Reflection Measurements
When measuring devices with high return loss (>10 dB), reflection accuracy is typically dominated by
the effective system directivity, instrument linearity errors, and noise uncertainty. With low return loss
devices (<10 dB), reflection accuracy is typically dominated by source match. Calibration with an open
and short effectively removes uncertainties due to frequency response of the source, sensors, and signal
splitting device.
Reflection Accuracy = Scalar Accuracy+ Reflection Bridge Accuracy
Figure 1-4: Reflection Uncertainty Relative to Directivity
Figure 1-5: Reflection Uncertainty Relative to Source Match
010203040
5
4
3
2
1
0
-1
-2
-3
-5
-4
Maximum Error (dB)
Directivity = 30 dB
Directivity = 30 dB
Directivity = 35 dB
Directivity = 35 dB
Directivity = 40 dB
Directivity = 40 dB
0
10 20 30 40
2
1
0
-1
-2
-3
-4
DUT Return Loss (dB)
Maximum Error (dB)
VSWR = 2
VSWR = 2
VSWR = 1.5
VSWR = 1.5
VSWR = 1.25
VSWR = 1.25