Transmission Line Parameters
If we consider an infinite lossless transmission line, we can determine the inductance L and capacitance C per unit length from geometric field considerations. The three physical embodiments that are of interest are the two-wire transmission line, the coaxial transmission and the microstrip transmission line (a simple parallel-plate approximation).
Transmission Line Discontinuities and Load Impedances
If the wave on a transmission line of characteristic impedance Zo arrives at a boundary with different Zo, or at a discontinuity, lumped load or termination of Z ? Zo, the single wave moving in the +z direction cannot simultaneously satisfy the boundary conditions relating V(z) to I(z) on both sides of the boundary. On one side of the boundary V(z)/I(z) = V+/I+ = Zo and on the other side V(z)/I(z) = (V++V-)/(I+-I-) = ZL.
Visualization of Standing Waves
The following set of graphs show the development of the reflected wave, beginning with an initially advancing incident wave moving to the reader's right, which is just about to reach the load point of reflection. For these graphs, Zo=50? and ZL=100? .
I
n the next graph, the incident wave has reached the point of reflection, and the reflected wave can be seen to be moving back to the reader's left. In this picture, the waveforms add to a greater magnitude.
DOWNLOAD THE WHOLE DOCUMENT HERE
If we consider an infinite lossless transmission line, we can determine the inductance L and capacitance C per unit length from geometric field considerations. The three physical embodiments that are of interest are the two-wire transmission line, the coaxial transmission and the microstrip transmission line (a simple parallel-plate approximation).
Transmission Line Discontinuities and Load Impedances
If the wave on a transmission line of characteristic impedance Zo arrives at a boundary with different Zo, or at a discontinuity, lumped load or termination of Z ? Zo, the single wave moving in the +z direction cannot simultaneously satisfy the boundary conditions relating V(z) to I(z) on both sides of the boundary. On one side of the boundary V(z)/I(z) = V+/I+ = Zo and on the other side V(z)/I(z) = (V++V-)/(I+-I-) = ZL.
Visualization of Standing Waves
The following set of graphs show the development of the reflected wave, beginning with an initially advancing incident wave moving to the reader's right, which is just about to reach the load point of reflection. For these graphs, Zo=50? and ZL=100? .
I
n the next graph, the incident wave has reached the point of reflection, and the reflected wave can be seen to be moving back to the reader's left. In this picture, the waveforms add to a greater magnitude.
DOWNLOAD THE WHOLE DOCUMENT HERE
No comments:
Post a Comment