Recall that a current will reflect when there are changes in the electrical properties of the material. In order to efficiently send the signal into the transmission line, it is important that the transmission line has the same impedance as the elements, otherwise some of the signal will be reflected back into the antenna. This leads to the concept of impedance matching, the design of the overall system of antenna and transmission line so the impedance is as close as possible, thereby reducing these losses. Impedance matching between antennas and transmission lines is commonly handled through the use of a balun, although other solutions are also used in certain roles. An important measure of this basic concept is the standing wave ratio, which measures the magnitude of the reflected signal. COUNT 4
QSN1 What sort of changes in material would a current reflect? ANS1 electrical QSN2  What must match between the transmission line and elements? ANS2 impedance QSN3 What technique is used to prevent unintentional decrease in signal? ANS3 Impedance matching QSN4 How is this process usually used for transmission lines and antennas? ANS4 balun