This program is an animation of the reflection and transmission of transverse electromagnetic waves at a general impedance discontinuity.

Consider two sections of coax or other TEM transmission line joined together. The left section is characterized by phase velocity Vo and impedance Zo. The right section is characterized by phase velocity Vl and impedance Zl. At the interface of the sections an impedance Zd is attached.

Let a wave be launched to the right in the left section. Application of boundary conditions at the interface yields the waveforms of current and voltage reflected at the interface, and the waveforms transmitted to the right section.

In composing a problem, the following variables are also required:

A: N:

After composition of a problem, the following quantities are displayed:

Fundamental: The phase velocity of the left section divided by its length. This is the frequency of a sine wave of period equal to the length of the left section.

Ao: Al: When setting the phase velocities and lengths of the system extensive use should be made of Zoom and the markers. The location of the discontinuity is always 0 on the x axis.

The lengths of sections one and two are proportional to their phase velocities, so that they have the same electrical length. The operator specifies the total length of the combined sections.

The distributed inductance in Henry/meter and the distributed capacitance in Farad/meter are computed from the phase velocity and characteristic impedance, and displayed for both sections of coax.

During the animation the time is displayed continuously.

The impedance attached at the discontinuity is to be expressed as a function of the Laplace transform variable s in the usual way.

A wide variety of waveforms may be launched. Characteristics of these waveforms may be controlled using parameters P1 and P2.

The spectra of these waveforms may be viewed in the spectrum window. This window presents incident, reflected, and transmitted power.

Ramp

P1: P2: Square

P1: P2: Sine

P1: P2: Pulse: P1: P2: Pulse1: P1: P2: Pulse2: P1: P2: Noise: P1: P2: Copyright 1998 DSBirkett

For upgrades and detail view of the HP VEE programs as well as teaching materials, contact David Birkett at [email protected] or call 617 497 0907.

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