4. Error settings

4.1 Systematic errors

There are four types of errors: directivity errors, mismatch errors, frequency response errors, and isolation errors.

Directivity errors are caused by the fact that, when using couplers (or bridges) in a reflection setup, unwanted directivity signals are superimposed on the signal reflected by the device under test, thereby causing measurement errors in reflection. The more directional the coupler, the lower the directivity errors. The main cause is non-infinite directivity, defined by the ratio between the isolated (loaded) channel and the coupled channel of the coupler (or bridge) used.

Mismatch errors cover all the different impedance mismatches relative to the reference impedance (mismatch of the generator, couplers,...