Single‐ and double‐stub impedance matching on transmission‐line feeders are described. Formulae determining the position and the length of a single matching stub for any load impedance or any observed standing‐wave voltage distribution are derived, neglecting losses in the matching sections. Conditions for minimum length of stub and minimum distance between load and stub are specified. For the double‐stub arrangement, expressions for the lengths of and distance between stubs are derived for any possible combination of load and distance between stubs. A double‐stub tuner with any fixed distance between stubs cannot match all loads to the feeder, and the limits are specified. The optimum location on the feeder of the double‐stub tuner is discussed. A graphical method employing a circle diagram for computing the lengths and position of the stubs is explained. The graphical determination of the stub lengths of the double‐stub tuner is facilitated by auxiliary circular loci which also indicate the range of admittances over which an impedance match may be effected.
The American Institute of Physics