t of the incident energy would be absorbed and there would be little V1,i, rebounce or reflected energy (T 0). Finally if the Reflected wave wall was made of air, the ball will simply go through Fig. 2.2-12 Incident and reflected waves on a transmission line. the air wall and carry all its incident power with it (T = 0). There will be no reflected energy because back towards the source If the source impedance (Zs) is the incident energy would simply be expended in equal to Zo, the reflected wave from the load will be carrying the ball further. Note in this case that the absorbed in the source and no further reflections will transmission medium resistance is air, and it is the occur. If Zs is not equal to Zo, a portion of the reflected same as the air wall resistance which is the load and wave from the load is re-reflected from the source back we simply say that the load is matched to the toward the load and the entire process repeats itself until transmission medium. all the energy is dissipated. The degree of mismatch By measuring the angle of the re-bounce relative to between Z and ZL or Zs determines the amount of the the incident direction, it is possible to tell whether incident wave that is reflected. the wall is vertical and facing the thrower or whether By definition it is at an angle (phase) to the face-on position. Hence we can determine the direction of the wall. voltage reflection coefficient = Ureflected = Vincident The path through which the ball travels is called the transmission path. (2.2.23) Last but not least, you need not even physically touch the wall to find out some of its characteristics. In other words, measurement is indirect. This is useful current reflection coefficient = `reflected TiLA in the measurement of transistors where the ele- ments cannot be directly touched. It is also very (2.2.24) useful when you want to measure the impedance of an aerial on top of a high transmitting tower when your measuring equipment is at ground level. The From inspection of the circuit of Figure 2.2-1