Commit a4592ee3 authored by Claude Meny's avatar Claude Meny

Update textbook.fr.md

parent 5f077463
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...@@ -38,7 +38,7 @@ $`\left(\begin{array}{l} ...@@ -38,7 +38,7 @@ $`\left(\begin{array}{l}
<br> <br>
* Similarly for TM modes : * Similarly for TM modes (TM = transverse-magnetic) :
$`\overrightarrow{E}_{\parallel}=`$ $`\overrightarrow{E}_{\parallel}=`$
$`\left(\begin{array}{l} $`\left(\begin{array}{l}
...@@ -51,28 +51,11 @@ $`\overrightarrow{B}_{\parallel}=-2\,E_0\,\sin\,(k\; y\, \cos\theta) ...@@ -51,28 +51,11 @@ $`\overrightarrow{B}_{\parallel}=-2\,E_0\,\sin\,(k\; y\, \cos\theta)
\cdot \sin\big(k\;z\,\sin\,\theta -\omega t\big)\overrightarrow{e_z}`$ \cdot \sin\big(k\;z\,\sin\,\theta -\omega t\big)\overrightarrow{e_z}`$
![](media/image199.png)
![](media/image201.png){width="1.753584864391951in"
height="1.7708333333333333in"}
>
![](media/image202.png)![](media/image204.png)Figure 4.1:
[]{#_bookmark81 .anchor}TE and TM waves and their corresponding
standing wave be- haviour along the *y* axis.
---------->
* Similarly for TM modes (TM = transverse-magnetic)
_equations_
These results are dictated by the boundary conditions at the air-metal These results are dictated by the boundary conditions at the air-metal
interface which impose that for every point on the boundary surface interface which impose that for every point on the boundary surface
and for all times the tangential component of the electric field and for all times the tangential component of the electric field $`\overrightarrow{E}_{\parallel}`$
(incident + reflected) and the perpendicular component of the (incident + reflected) and the perpendicular component of the
induction field (incident + reflected) to be zero: induction field $`\overrightarrow{B}_{\perp}`$ (incident + reflected) to be zero:
$`\overrightarrow{E}_{\parallel}=0\quad\text{and}\quad\overrightarrow{B}_{\perp}=0`$. $`\overrightarrow{E}_{\parallel}=0\quad\text{and}\quad\overrightarrow{B}_{\perp}=0`$.
...@@ -80,31 +63,23 @@ $`\overrightarrow{E}_{\parallel}=0\quad\text{and}\quad\overrightarrow{B}_{\perp} ...@@ -80,31 +63,23 @@ $`\overrightarrow{E}_{\parallel}=0\quad\text{and}\quad\overrightarrow{B}_{\perp}
* For TE modes, * For TE modes,
this results in the fact that the total electric field this results in the fact that the total electric field
$`\overrightarrow{E}_{\perp}`$ (it is only tangential by definition) has nodes for $`\overrightarrow{E}_{\perp}`$ (it is only tangential by definition) has nodes for
$`y=\frac{}{}=\frac{}{}=\frac{}{}`$ where $`k_y=k\,\cos\theta`$ is the y component $`y=\frac{n\pi}{k\,\cos\theta}=\frac{n\pi}{k_y}=\frac{n\lambda}{2\cos\theta}`$ where
of the wavevector. $`k_y=k\,\cos\theta`$ is the y component of the wavevector.
* For TM modes, * For TM modes,
we have instead $`\overrightarrow{E}_{\parallel\,,z}=0`$ as the z component of the we have instead $`\overrightarrow{E}_{\parallel\,,z}=0`$ as the z component of the
total electric field represents the tangential component. total electric field represents the tangential component.
As the tangent component of the electric field is zero in the nodal planes, As the tangent component of the electric field is zero in the nodal planes,
$`y=dfrac{\pi}{k_y}=dfrac{\pi}{k_y}=dfrac{\pi}{k_y} $`y=frac{\pi}{k_y}=frac{2\pi}{k_y}=frac{3\pi}{k_y}=\dots`$
> for TE and TM modes, placing a new conducting plate at
*y* = *[π]{.underline} ,* [2*π*]{.underline} *,* [3*π*]{.underline}
>
. . . for TE and TM modes, placing a new conducting plate at
>
*ky ky ky*
>
the position of these planes would not disturb the total electric the position of these planes would not disturb the total electric
field. Let's for instance place a conductive plate at the position of field. Let's for instance place a conductive plate at the position of
the first node *y* = *b* = *[π]{.underline}* for a TE wave. We can see the first node $`y=b=\frac{\pi}{k_y}`$ for a TE wave. We can see
that the incident wave, after striking the first plate will be that the incident wave, after striking the first plate will be
reflected towards the second plate where now will replicate the same reflected towards the second plate where now will replicate the same
refection phenomenon with exactly the same incident angle and refection phenomenon with exactly the same incident angle and
automatically automatically satisfying the boundary conditions for the electric field: we have
>
satisfying the boundary conditions for the electric field: we have
obtained the confinement of the wave, i.e. the wave is guided. obtained the confinement of the wave, i.e. the wave is guided.
chap4 Rectangular waveguides chap4 Rectangular waveguides
......
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