In this equation is the total voltage anywhere on the line (at any point z), is the total current anywhere on the line (at any point z), and are the phasors of forward and reflected voltage waves at the load (where z=0), and and are the phasors of forward and reflected current wave at the load (where z=0).These voltages and currents are also phasors and have a constant magnitude and phase in a specific circuit, for example , and . We can get the time-domain expression for the current and voltage on the transmission line by multiplying the phasor of the voltage and current with and taking the real part of it.

If the signs of the and terms are oposite the wave moves in the forward direction. If the signs of and are the same, the wave moves in the direction.

In the next several sections, we will look at how to find the constants , , , , . In order to find the constants, we will introduce the concepts of transmission line impedance , reflection coefficient , input impedance .

In the following simulation, we have three waves as a function of distance z. One is fixed with a constant phase of , and for the other two signals the phase can be changed manually by changing the slider t that represents time. In the simulation, and . This simulation is realistic only if time moves forward from 0 to 5. Observe how phase change as the time increases from 0 to 5, then answer the question below.

The sign in front of and is opposite for the forward going wave.

True False