1. Voltage measurement

At radio frequencies (frequencies above 100 kHz), voltage measurement poses a number of special problems: on the one hand, voltage amplitude varies periodically along a mismatched line, so voltage measurement only makes sense if you specify the plane in which it is performed; on the other hand, the notion of power becomes more important than that of voltage as frequency increases.

To carry out these voltage measurements, different devices are used, depending on the frequency of the signal to be measured.

• High-impedance measurements are carried out using voltmeters or oscilloscopes fitted with probes; voltmeters of similar design to those found at medium frequencies can measure signals up to frequencies of the order of 2 GHz to 3 GHz. Oscilloscopes (conventional or sampling), fitted with a high-impedance probe, can...