
- •Advanced chapters of theoretical electroengineering.
- •Lecture 4
- •Image method for the flat boundary between dielectrics.
- •Image method for the flat boundary between dielectrics.
- •Image method for the flat boundary between dielectrics.
- •Image method for the flat boundary between dielectrics.
- •Image method for the flat boundary between dielectrics.
- •Equivalent charge density.
- •Method of images for cylindrical boundaries between dielectrics.
- •Problem formulation
- •The inverse point
- •Normal component of the field intensity
- •Normal component of the field intensity
- •Geometrical relations
- •Angles
- •Geometrical relations
- •Geometrical relations
- •Trigonometric relations
- •Trigonometric relations
- •Geometrical relations
- •Field induced by the line sources
- •Geometrical relations
- •The field sources for the external domain
- •The field sources for the internal domain
- •Application of the Images Method for calculating magnetic fields in the presence of
- •Image method for the flat boundary between magnetic media.
- •Equivalent magnetic charge density.
- •The field in the presence of a cylindrical magnetic object
- •The field sources for the magnetic field intensity in the external domain
- •The field sources for the magnetic field intensity in the internal domain
- •Images of a two-wire transmission line (external domain)
- •Dependence of the field intensity on the coordinate
- •Inductance of the two-wire transmission line per unit length
- •External fluxes
- •Total inductance
- •Forces. The first line.
- •Forces. The second line.

Field induced by the line sources
The normal component of |
|
|
|
|
|
||
the field intensity induced |
|
|
P |
|
|
||
by the charged line in the |
|
|
|
||||
cylinder center |
|
b |
|
|
|
||
|
|
|
|
||||
|
C |
1 |
|
|
a |
C |
|
EnC |
|
|
|||||
|
|
|
|
|
B |
|
|
2 0 |
r |
A |
|
|
|
||
|
|
|
|
The normal component of the field intensity induced by the charged line in the inverse point:
EnB |
B |
1 |
cos |
2 0 |
a |
21

Geometrical relations
The normal component of |
|
|
|
|
|
|
|
P |
|
|
|||||
|
|
|
|
|
b |
|
|
|
|||||||
the field intensity induced |
|
|
|
|
|
|
a |
|
|||||||
by the surface charges |
|
|
|
|
|
|
C |
||||||||
|
|
|
|
|
|
||||||||||
may be expressed as |
|
|
A |
|
|
|
|
|
B |
|
|||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
||
|
|
|
2 |
1 |
|
|
|
|
|
2 |
1 |
|
1 |
|
|
E |
|
cos( ) |
|
|
|
|
|
||||||||
|
|
|
|
|
|
|
|
|
|||||||
n |
2 0 |
|
2 |
|
|
a |
|
2 0 |
|
2 |
|
|
|
|
|
|
|
1 |
|
|
1 r |
|
|
The first term corresponds to field induced by the charged line in the inverse point. The second term corresponds to field induced by the charged line in the central point.
|
|
|
|
|
2 |
1 |
|
|
|
|
|
|
2 |
1 |
|
|
|
B |
|
|
|
|
C |
|
|
|
|||||||
|
|
|
|
|
|
|||||||||||
|
|
2 0 |
|
2 |
|
|
|
|
2 0 |
|
2 |
|
|
|||
|
|
|
|
1 |
|
|
|
|
1 |
22

The field sources for the external domain
0 |
r |
0 |
|
|
A B C
00
|
0 |
|
0 |
||
|
23

The field sources for the internal domain
0 |
r |
0 |
|
|
A C
2 0 0
24
Application of the Images Method for calculating magnetic fields in the presence of cylindrical objects
25

Image method for the flat boundary between magnetic media.
|
|
|
|
|
H (1) |
|
H |
(2) |
|||
|
|
|
Boundary conditions: |
1 |
n |
|
2 |
|
n |
||
|
|
|
|
|
|
|
|
|
|
||
|
i |
y |
|
|
|
H (1) |
H (2) |
|
|||
|
|
|
|
|
|
|
|
|
|
|
|
1 |
h |
r |
x |
For the chosen coordinate system: |
|||||||
|
|
|
|||||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
H |
(1) |
|
H |
(2) |
|
||
|
|
2 |
|
1 |
y |
|
2 |
|
y |
|
|
|
|
|
|
H x(1) |
H x(2) |
|
|||||
|
|
|
|
|
|
26

Equivalent magnetic charge density.
Assuming the same magnetic permeability in the whole space: |
1 |
i y
1 |
h |
r |
x |
|
|
|
|
|
|
|
|
|
|
1 |
|
|
|
Charge density H y(1) |
|
m |
|||
H y2 |
|
||||
|
|
|
|
1 |
|
|
(x) 2 |
1 2B(ext) |
||
|
m |
|
1 |
|
n |
|
|
|
2 |
(1) |
(ext) |
|
|
m |
|||
Hn |
Hn |
|
|
|
|
||
2 1 |
|||||||
|
|
|
|
||||
(2) |
(ext) |
|
|
m |
|||
Hn |
Hn |
|
|
|
|
|
|
|
|
2 1 |
|||||
|
|
|
|
|
27

The field in the presence of a cylindrical magnetic object
0 |
r |
|
i |
|
A C
28

The field sources for the magnetic field intensity in the external domain
0 r 0
A B C
i
i 0
0
i 00
29

The field sources for the magnetic field intensity in the internal domain
0 r 0
A C
i 2 0
0
30