MISMATCH Describes nonideal coupling between two circuits. Not all of the available signal is transferred, part of the signal is reflected at the connector, leading to a measurement error. The degree of mismatch is specified by the reflection coefficient and the standing wave ratio. The most critical point in spectrum analysis is the connection between the device under test and the input of the analyzer; in network analysis, the connection between the tracking generator output and the device under test is also important. By means of an external high-precision low-reflection attenuator mismatching errors can frequently be corrected to such an extent that the error contribution resulting from the mismatching can largely be ignored.
MIXER LEVEL Describes the input level to the 1st mixer of the analyzer. The mixer level is dependent on the input signal level (Lin), the setting of the input attenuator (ATTN) and the insertion loss (a0) of the input stage or external devices like attenuators:
Lmixer (dBm) = Lin (dBm) — ATTN (dB) — a0 (dB)
The mixer level influences the harmonic distortion, intermodulation, signal-to-noise ratio (noise floor) and dynamic range of the analyzer. It can be adjusted to optimize these various factors.
