Measurement errors
Measurement errors in network analysis can be separated into two categories: random
and systematic errors. Both random and systematic errors are vector quantities. Random
errors are non-repeatable measurement variations and are usually unpredictable.
Systematic errors are repeatable measurement variations in the test setup.
Systematic errors include impedance mismatch, system frequency response and leakage
signals in the test setup. In most microwave measurements, systematic errors are the
most significant source of measurement uncertainty. The source of these errors can be
attributed to the signal separation scheme used.
Numerous publications are available on vector network analyzer (VNA) calibration
techniques. References [1], [2], [3], [4], [5], [6], [7] and [8] are just some of the pub-
lished work. Agilent’s application notes: 1287-1, 1287-2 and 1287-3 also provide insights
on VNAs and VNA error correction. It is recommended that a user be familiar with these
calibration techniques and terminologies to get the maximum understanding from this
application note.