Bird Technologies 5015 Series-Manual - Manual (Page 22)

10
Note:
If a source with a 1.30:1 VSWR was
used instead, the mismatch uncertainty would be:
Using a lower VSWR source can drastically reduce the
mismatch uncertainty. Keep in mind that the typical
VSWR of the Model 5011 is 1.03:1, which gives a much
lower mismatch uncertainty.
Example - With the 1.50:1 source, the mis-
match uncertainty would be:
To determine the total uncertainty of the measure-
ment, combine the RSS uncertainty with the mis-
match uncertainty using the RSS method. Square the
RSS uncertainty, add it to the square of the mismatch
uncertainty, and take the square root.
Using Example 1 in Table 3 with a source VSWR of
1.50 and a TPS VSWR of 1.20, the total uncertainty
would be:
For example 2, the total uncertainty would be 6.82 %.
ρ
s
1.30 1 –
( ) 1.30 1
+
( ) ⁄
0.130 = =
ρ
1
1.20 1 –
( ) 1.20 1
+
( ) ⁄
0.091 = =
MU 1 0.130 0.091
Ч
+
( ) 2
1 –
[ ] 100
2.39
±
=
Ч
=
ρ
s
1.50 1 –
( ) 1.50 1
+
( ) ⁄
0.200 = =
ρ
1
1.03 1 –
( ) 1.03 1
+
( ) ⁄
0.015 = =
MU 1 0.200 0.015
Ч
+
( ) 2
1 –
[ ] 100
0.59
±
=
Ч
=
5.00
2
3.67
2
+ 6.20 percent
( )
=