Why do TEM modes need two conductors to propagate?

In summary, TEM modes are electromagnetic waves that require two conductors and a dielectric medium to propagate. The interaction between the electric and magnetic fields in the space between the conductors is essential for the wave to carry energy. A system with only one conductor cannot support TEM modes, and the dielectric medium plays a crucial role in maintaining the separation between the conductors and affecting the characteristics of the mode. And finally, TEM modes can exist in systems with more than two conductors, but the mode structure and characteristics may vary.
  • #1
klawlor419
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Why do we need two conducting surfaces to allow TEM modes to propagate through a waveguide? Why can we not propagate TEM waves through a single conducting waveguide?
 
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  • #3
With only one conductor, the only solution that satisfies E_tangential at the conductor equal to zero is E=0 everywhere.
 

Related to Why do TEM modes need two conductors to propagate?

Question 1: What are TEM modes?

TEM modes, or transverse electromagnetic modes, are the electromagnetic waves that propagate in a system with two conductors separated by a dielectric medium. These modes are characterized by having both electric and magnetic fields perpendicular to the direction of propagation.

Question 2: Why do TEM modes need two conductors to propagate?

TEM modes require two conductors to propagate because they rely on the interaction between the electric and magnetic fields in the space between the conductors. This interaction is necessary for the wave to propagate and carry energy from one conductor to the other.

Question 3: Can TEM modes propagate in a system with only one conductor?

No, TEM modes cannot propagate in a system with only one conductor. As mentioned, these modes require the interaction between two conductors to propagate. In a system with only one conductor, there is no electric field to interact with and therefore no TEM mode can exist.

Question 4: What role does the dielectric medium play in TEM mode propagation?

The dielectric medium between the two conductors plays a crucial role in TEM mode propagation. It acts as an insulator and helps to maintain the separation between the two conductors, allowing for the electric and magnetic fields to interact and propagate the wave. The properties of the dielectric medium, such as its permittivity and permeability, also affect the speed and characteristics of the TEM mode.

Question 5: Can TEM modes exist in systems with more than two conductors?

Yes, TEM modes can exist in systems with more than two conductors. As long as there is a dielectric medium separating the conductors and the necessary electric and magnetic field interactions are present, TEM modes can propagate in systems with any number of conductors. However, the mode structure and characteristics may vary depending on the number and arrangement of the conductors.

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