Measurements of Standing Waves

At radio frequencies where slotted waveguide or transmission line sections would be excessively long, probe measurements of the relative current (or relative voltage) amplitudes at discrete sampling points along the waveguide provide a convenient and practical technique for measuring the complex impedance and related parameters. The SMITH CHART is useful for interpreting and evaluating data obtained from such measurements as will be described herein. The principle is made use of in the SMITH CHART plotting board shown.