HP HP 8712ET, User Manual, Page: 224 / 480

5-18 ET User’s Guide
Optimizing Measurements
Compensating for Phase Shift in Measurement Setups
To use the port extension feature, press ,
. When port extension is
turned on, you can add delay independently to both the reflection port
and the transmission port.
To add delay between the REFLECTION RF OUT port and your DUT,
press
, and enter the delay value.
To add delay between the TRANSMISSION RF IN port and your DUT,
press
, and enter the delay value.
TIP
A good way to know when you have added enough delay is to connect a
short in place of the DUT. Adjust the port extension until the phase
response is flat. (Remember that most short-circuit standards have a
nonzero delay, so adjusting delay using this method will result in a delay
error equal to two times the short delay.)
The delay values that you enter will be automatically applied
appropriately to both transmission and reflection measurements. When
measuring reflection, the reflection port extension delay is applied twice.
When measuring transmission, the reflection port extension delay and
the transmission port extension delay are each applied once.
Electrical Delay
Another type of reference plane extension is ,
accessible from the key. Electrical delay lets you add delay to
your current measurement to compensate for phase shift. To flatten the
phase response at a certain frequency, use
. This automatically
adjusts the electrical delay to compensate for the phase slope at the
active marker position.
Electrical delay is commonly used in transmission measurements to
measure a device’s electrical length, or to remove phase slope to measure
deviation from linear phase.
Unlike port extension, electrical delay does not automatically adjust the
applied delay when you switch between transmission and reflection
measurements. For this reason, port extensions are preferred over
electrical delay for fixture compensation or when measuring one-port
devices.
NOTE Reference plane extension only affects measurements using the
narrowband detectors.
CAL
More Cal
Port Extensions Port Ext's on OFF
Refl Port Extension
Trans Port Extension
Electrical Delay
SCALE
MARKER
Marker Functions Marker -> Elec Delay