Agilent Technologies E4418B Service Manual page 144

Measurement Uncertainty Analysis – Power Reference Level Test
Measurement Introduction
Consider the model below:
An estimate of the moduli of Pd and Ps are each less than a specified value. Ps and Pd
each lie within a circle of radius P. Assuming Pd and Ps have equal probability of
lying anywhere within the circle the standard uncertainty of Mismatch becomes
(
u Ms
Ps is the reflection coefficient of the source, which is specified as less than 1.05.
The reference is designed to have a VSWR of less than 1.05.
Hence,
( ) (
Ps max Pd max
=
B-6
P
⋅
maxP s maxP d
) ±
------------------------------------------- -
=
2
<
VSWR 1.05
<
VSWR 1.05
VSWR 1 1.05 1
–
)
= ---------------------------- - = --------------------- -
VSWR + 1 1.05
Agilent E4416A/E4417A Service Guide
–
0.0244
=
+ 1