HP 85106D, Manual

Page: 68 / 244

HP 85106D mm-Wave System 2-23
Operation
1-Port Calibration
1-Port Calibration
The S
11
1-Port or S
22
1-Port calibration requires three standards to quantify
and remove the system frequency response, source match, and directivity
errors. These calibration types provide the best accuracy for reflection
measurements of 1-port devices. The standards used for this calibration are:
•
Flush short
•
Quarter-wave offset short
•
Z
o
termination
The three choices for Z
o
termination are:
•
Fixed load
•
Sliding load
•
Load/offset load combination
The load/offset load combination is preferred.
Choosing the Proper
Load Standard
In the 1-Port calibration a load termination is used to determine the system
directivity. (The error signal that appears in the reflected signal path and did
not reach the test port). This section describes the different load standards
that can be used with the HP 8510C.
A fixed load is the simplest load standard and provides adequate
performance for many applications. During the calibration that uses a fixed
load, the load is assumed to be perfect. The measured directivity is the
combination of the actual system directivity and the actual reflection
coefficient of the load. The effective system directivity is therefore
dependent on the reflection coefficient of the load element (see Figure 2-4a).