Chapter 2 187
Performance Verification Tests
24. Frequency Response, Agilent E4404B, E4405B, E4407B, and E4408B

24. Frequency Response, Agilent E4404B,

E4405B, E4407B, and E4408B
This test measures the amplitude error of the analyzer as a function of
frequency. To measure frequencies of 100 kHz and greater, the output of
a source is fed through a power splitter to a power sensor and the
analyzer. A function generator is used as the source from 100 kHz to
10 MHz, and a synthesized sweeper at 10 MHz and greater. To measure
frequencies below 100 kHz, a DVM with a 50 Ω load replaces the power
sensor.
For improved amplitude accuracy the power splitter is characterized
using a “reference” sensor connected to one power splitter output port.
The other power splitter output port connects to the “buried” sensor; it
is not removed from the power splitter. Once the characterization is
done, the reference sensor is removed and replaced by the analyzer.
Measurements are made at the same frequencies used in the
characterization. The analyzer marker amplitude measurements are
corrected using the characterization data to determine the absolute
flatness error and the flatness error relative to 50 MHz.
To measure frequencies greater than 3 GHz, the source power level is
adjusted at 50 MHz to place the displayed signal at the analyzer center
horizontal graticule line. The power meter is then set to measure dB
relative to the power at 50 MHz. At each new source frequency and
analyzer center frequency, the source power level is adjusted to place
the signal at the center horizontal graticule line. The power meter
displays the inverse of the frequency response relative to 50 MHz.
This procedure does not test frequency response with the optional
preamplifier (Option 1DS) turned on. If the analyzer is equipped with a
preamplifier, also perform the “Frequency Response, Preamp On”
procedure. Analyzers with Option UKB are tested down to 100 Hz in dc
coupled mode. In ac coupled mode, Agilent E4404B and E4405B
analyzers are tested down to 100 kHz. Agilent E4407B analyzers with
Option UKB are tested down to 10 MHz in ac coupled mode.
The related adjustment for this performance test is “Frequency
Response.”
Equipment Required
Synthesized sweeper
Function generator
Power meter
RF Power sensor (2 required)
Microwave power sensor
Microwave power splitter
Digital multimeter