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Important features of Transverse ElectroMagnetic Mode |
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For TEM mode the electric field, the magnetic field and the direction of modal propagation are perpendicular to each other. |
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This mode is similar to the TEM wave in an unbound medium. |
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The ratio of  to  is equal to the intrinsic impedence of the medium |
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 -------- (6.16) |
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The field orientation of this mode will be as shown in the figure |
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Since the modal field for TEM mode is identical to that in the unbound medium one would ask a question whether the wave guide boundaries play any role in propagation of the TEM mode? |
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If we look at the fields of the TEM mode we note that electric field is perpendicular to the wave guide walls and magnetic field is parallel to the wave guide walls. Since neither normal components of electric field nor tangential component of electric field has boundary conditions the fields are not altered by the presence of the wave guide wall. The conducting waves are therefore transparent to the waves and the wave propagates as if it is propagating in an unbound media. |
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The face constant of the mode is equal to the face constant of uniform plane wave in the medium. |
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In most of the two conductor system(Transmission Lines) like the parallel wire line, co-axial cable etc., the propagation of electromagnetic energy takes place through this mode. |
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