In both coaxial and waveguide system, HF scattering parameters (S-parameters, reflection and transmission coefficients) of passive one-port and two-port networks (reflection and transmission transfer standards) are measured by network analysers. The upper frequency limit is curently 50 GHz in coaxial lines and 40 GHz for waveguides. The characteristic impedance for the line system used is traced back to the units of length and time. As impedance and phase standards, waveguide and coaxial line sections of known length are used, manufactured with highest precision, without dielectric beads and with a characteristic impedance calculated from the cross section data (so-called "air lines"). With respect to the measurand attenuation (magnitude of the transmission factor) the network analyser has been traced to the attenuation standard measuring set-ups.

Impedance standards (air lines) and test devices in 3.5 mm and 2.92 mm coaxial technique