The Transverse Electromagnetic (TEM) Wave

A solution to the wave equation is given by

The wave below is a TEM wave, the sort you might find in a coax cable from a signal generator to an oscilloscope. It could also be a radiowave or microwave.

Click on the start button to set the wave moving. The animation may take some time to load. the animation loops.

The wave propagates through our window of vision, toward the right. Notice that at the 'front' of the wave, there is always a point of constant phase.This applet can take 3 minutes to start, sorry !

This kind of wave is said to be Transverse Electromagnetic (TEM.) The E field and the H field are both at 90o to the direction of propagtion.

The wave is not just a line, but exists in an entire plane. The TEM Wave is a type of plane wave.

If the wave is propagating in a vacuum, the amplitude of the H-Field is related to the amplitude of the E-Field by the characteristic impedance of free space, zo. The propagation velocity in free space is c = 3 x 108 ms-1.

In text books, the TEM Wave is commonly shown as in the figure below. The arrows indicate whether the wave is approaching a maxima or minima and the seperation of the lines shows the field strength.

Page Last Revised : 15th March 1997
©1997 Mike Link
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