04680538 is referenced by 75 patents.
A vector network analyzer system for measuring the complex impedance of devices and components at millimeter wavelengths is disclosed. A pair of directional couplers provide samples of the signal incident on and reflected from the element under test through reference and test channels, respectively. A 180.degree. hybrid, or magic tee, device receives the samples, mixes them vectorially, and produces outputs to two power detectors which provide amplitude and phase information about the complex reflection coefficient. Similar measurements are obtained for the complex transmission coefficient. A 90.degree. phase shifter consisting of a second magic tee and a PIN diode is connected in the reference channel to eliminate a phase measurement ambiguity. A computer processes the power detector output to determine the value of the unknown impedence. An electronically swept signal source allows measurements to be made automatically over a wide frequency band.