Quality assurance
in specifications
The following examples demonstrate
the reliability and comprehensive-
ness of specifications. Although
the absolute accuracy for a 3 dB
attenuator is specified as ±0.3 dB,
test data statistics indicate an
expected value of 3 dB ±0.20 dB
from dc to 18 GHz. Similarly a
30 dB attenuator is specified as
±1.0 dB, but typically is no worse
than 30 dB ±0.75 dB from dc to
18 GHz. The other attenuation
values are also specified as
conservatively.
In addition, Agilent precision
attenuators meet more comprehensive
performance standards. Linear
phase response is an example. Not
only is wide bandwidth significant,
but also linear phase response is
an important parameter for appli-
cations where pulse distortion
must be kept to a minimum. The
excellent linearity of the Aglilent
attenuators is typified in the
accompanying illustration of
an actual network analyzer
measurement.
Economy
Automated procedures have result-
ed in economies of scale in produc-
tion and testing. The automated
resistive film deposition process
permits high-volume manufacture
with excellent yield. Furthermore,
characteristics are consistently
uniform; hand “touch-up” is not
required to meet specifications.
Automatic testing means excep-
tionally thorough, high-accuracy
measurements can be performed
in appreciably shorter time than
could be done manually.
The overall result is outstanding
attenuator performance at attrac-
tive prices.
Calibration data
Optional calibration data
Use of calibration data has always
been an effective means of reduc-
ing measurement uncertainty at
RF and microwave frequencies.
This data is available for Agilent’s
fixed attenuators as Option 849xx-
UK6. Data which is generated by
an automatic network analyzer
provides a tabulated list of
attenuation and SWR’s at 26 to
67 frequencies (see table 2).
Measurements to 60 dB are
directly traceable to NBS standards
and feature very low measurement
uncertainties. Option 849xx-UK6
data is available when the attenua-
tors are first purchased and recali-
brations are available through
Agilent Customer Service Centers
around the world.
4
Center trace is phase response of 8491A –6 dB
attenuator from 1.0 to 2.0 GHz taken with Agilent
8410 network analyzer. Top and bottom traces are ±1°
calibration. Linear phase component has been
compensated for with a line stretcher. Response,
therefore, shows nonlinear phase deviation of
< ±1/2° over 1 to 2 GHz band.