Why is del(E_t) zero in TEM mode of transmission lines?

In summary, the conversation discusses the concept of taking the divergence of transverse electric field as zero in equations 7.1.37 and 7.1.38 on page 192 of MIT opencourseware. The question is raised regarding the validity of this assumption, as the field does create a surface charge density on the transmission line. The response clarifies that the divergence of E is zero between the conductors due to the absence of charge in that space, and the surface charge density is only used for boundary conditions in solving for the fields.
  • #1
Adit112
I was going through MIT opencourseware https://ocw.mit.edu/courses/electri...s-spring-2009/readings/MIT6_013S09_chap07.pdf and I didnt understand exactly why in equation 7.1.37 and 7.1.38 in page 192 the divergence of transverse electric field is taken as zero ? The only reason this would be true is if the region is source free but we clearly see that this field does setup a surface charge density on the surface of the transmission line so intuitively and mathematically why would the divergence of Et be zero? I can always construct a surface in the transverse plane to include the transmission line which has charge and so the del.Et should be equal to the surface charge density isn't?
 
Engineering news on Phys.org
  • #2
The divergence of E is zero in between the conductors because there is no charge in that space. The surface charge density is only used for boundary conditions when solving for the fields.
 

1. Why is del(E_t) zero in TEM mode of transmission lines?

Del(E_t) is the symbol for the tangential electric field component in the transverse electromagnetic (TEM) mode of transmission lines. In this mode, the electric and magnetic fields are both perpendicular to the direction of wave propagation. This results in a cancellation of the tangential electric field component, making it zero.

2. What is the significance of del(E_t) being zero in TEM mode of transmission lines?

The fact that del(E_t) is zero in TEM mode is important because it allows for the transmission of electromagnetic waves with minimal loss. This is because there is no energy dissipation from the tangential electric field component, leading to efficient transmission of power.

3. How does del(E_t) being zero affect the behavior of TEM mode in transmission lines?

Since del(E_t) is zero in TEM mode, the electric field is purely transverse to the direction of wave propagation. This results in a constant phase and amplitude of the electric field along the direction of the transmission line, leading to a uniform and stable transmission of waves.

4. Can del(E_t) ever be non-zero in TEM mode?

No, del(E_t) is always zero in TEM mode of transmission lines by definition. This is because TEM mode is characterized by the cancellation of the tangential electric field component, resulting in only transverse electric and magnetic fields.

5. How is del(E_t) related to the TEM mode dispersion equation?

The dispersion equation for TEM mode in transmission lines is derived by setting del(E_t) equal to zero. This is because the tangential electric field component is directly related to the propagation constant in the dispersion equation. By setting it to zero, we are able to solve for the characteristic impedance and wavelength of the TEM mode.

Similar threads

Current, B, E field directions on line in TEM mode
    • Electrical Engineering
Replies
1
Views
909
A Voltage and current waves in a transmission line
    • Electromagnetism
Replies
4
Views
970
Question on TEM mode transmission lines.
    • Electrical Engineering
Replies
18
Views
7K
What is the Truth About the Magnetic Field in TEM Mode in Transmission Lines?
    • Electrical Engineering
Replies
1
Views
2K
B A Magnetic Misconception on Divergence 0/Closed Field Lines?
    • Classical Physics
Replies
3
Views
408
A Relativistic conduction current density?
    • Special and General Relativity
Replies
3
Views
2K
How electric field lines going out from surface is zero?
    • Electromagnetism
Replies
4
Views
1K
Is the Total Charge of Polarization in a Non-Homogeneous Dielectric Zero?
    • Introductory Physics Homework Help
Replies
2
Views
1K
Conservative fields in a transverse plane of a transmission line
    • Advanced Physics Homework Help
Replies
1
Views
2K
I Why Do We Consider External Electric Fields in Gauss' Law Calculations?
    • Classical Physics
Replies
5
Views
2K

Hot Threads

Recent Insights

Back
Top