TABLE OF CONTENTS As discussed in previous chapters, a mismatch between the load impedance and the characteristic impedance (or between the load admittance and the characteristic admittance) of a waveguide or transmission line causes a reflection loss at the load and increased dissipative losses along the entire length of the line. Also, a mismatch termination causes the transmission phase to vary nonlinearly with changes in frequency or line length, and increases the tendency of the waveguide or line to overheat and arc over at the current and voltage maximum points, respectively, when operating under high power.
Several commonly used devices for obtaining a match at the load end of a transmission line will be described in this chapter. These include the single and the dual matching stub [65], and the single and the dual matching slug transformers. Matching stubs or building-out sections, as they are sometimes called, are sections of transmission line, frequently of the same characteristic impedance (or characteristic admittance) as that of the main line, and either open- or short-circuited at their far end, connected in shunt with the main line at any one of several permissible positions in the general location where it is desired to provide the match. Slug transformers, on the other hand, are sections of line of appropriate characteristic impedance (or characteristic admittance) and length connected in series with, and forming a continuation of, the main line.
These devices are described in some detail herein since it is...
