2
Introduction
Designers and manufacturers of active devices
often need to control the power level at the test
port
1
of their power-sensitive devices, but find dif-
ficulty in overcoming insertion losses. The insertion
losses occur as a result of connecting components
in the measurement path between the source and
the DUT. The Agilent Technologies 8510C is a
microwave network analyzer
2
capable of setting
and controlling the power level at the test port.
This product note reviews the implementation
and operational considerations of the 8510C’s
test port power flatness-correction feature.
The 8510C performs a flatness-correction cali-
bration by measuring the test port power level
using an Agilent power meter and creates a table
of power corrections versus frequency. The
power meter then stores the table into an Agilent
8360 series synthesized sweeper.
3
When the test
port flatness correction is enabled, the source
will adjust its output power to compensate for
path losses at each measurement point in the
frequency span.
1. In this document, “test port” will refer to the point in the system where the test
device is connected. This may be port 1 or port 2 of any 8510 coaxial-based test
set or the end of a cable or adapter that is attached to the DUT.
2. 8510B network analyzers with revision B.06 or later may also be used to achieve
constant test port power levels. To obtain the latest firmware revision order the
11575F upgrade kit.
3. Any 8360 synthesized sweeper with firmware revision of September 25, 1990 or
earlier must be upgraded. To upgrade your 8360 to the latest firmware revision,
order part number 08360-60167.
Power flatness correction is useful for characteriz-
ing active devices by allowing measurements of
absolute power, gain versus input power, and
swept-frequency gain compression. Swept-power
gain compression measurements are possible in
the power domain with the flatness correction
enabled.
The 8510XF measurement system is capable of lev-
eling and controlling the test port power between
45 MHz and 110 GHz without requiring a power
calibration for each measurement. When power lev-
eling is enabled, the test port power variation is
typically less than ±1 dB over the full frequency
sweep, with 20 dB of adjustable power. For more
information regarding power leveling in the Agilent
8510XF, refer to product note 8510XF-1, literature
number 5968-5270E.
