Specifications

Reflection measurements

The uncertainty of a reflection measurement such

as return loss, SWR, reflection coefficient and

impedance is affected by directivity, source match,

load match, and reflection tracking of the test sys-

tem. With a full two-port calibration, the effects of

these factors are minimized. A one-port calibration

can provide equivalent results if the amplifier has

sufficient isolation to reduce the effects of the load

match.

Nonlinear measurements

For absolute power measurements, a frequency

response calibration is used. Because the power

calibration is made relative to 50 Ω, inaccuracies

due to mismatch will occur when a device is

attached that is not exactly 50 Ω. Since the power

meter calibration feature is not a true leveling fea-

ture, it cannot correct for mismatches that occur

between the test port and the AUT. Mismatch can

be reduced by using attenuators at the input or

output of the AUT.

For a gain compression measurement a response

calibration reduces the frequency response errors.

A gain compression measurement requires the

power level to be changed after a calibration. The

Agilent 8360 Series sources, used with the 8510C

are specified to have a source linearity of ±.5 dB,

typically less then ±.2 dB. Source linearity uncer-

tainty can be reduced by performing a power flat-

ness correction at the input of the AUT. This pre-

cisely sets the power level incident to the AUT by

compensating the source power for any nonlinear-

ities in the source or test setup.