Chapter 8: Magnetic Field Stream Lines

Illustration 1

Observe the magnetic field stream lines in the following structures in DC mode.

Figures (click to enlarge)
single wire
loop
coil
two-wire line
(co-parallel currents)
two-wire line
(anti-parallel currents)
parallel-plate line
(anti-parallel currents)
coaxial line
(anti-parallel currents)
microstrip line
(anti-parallel currents)

 

Figure 1: The magnetic (H-field) streamlines of a single wire.

 

Figure 2: The magnetic (H-field) streamlines of a loop. The plot is in the   plane in a cylindrical coordinate system since the structure is rotationally symmetrical with respect to the z-axis. Thus, the plot shows only one-half of the loop's cross-section.

 

Figure 3: The magnetic (H-field) streamlines of an air-core coil. The plot is in the  plane in a cylindrical coordinate system since the structure is rotationally symmetrical with respect to the z-axis. Thus, the plot shows only one-half of the coil's cross-section.

 

Figure 4: The magnetic (H-field) streamlines of a two-wire line with currents flowing in the same direction.

 

Figure 5: The magnetic (H-field) streamlines of a two-wire line with currents flowing in opposite directions.

 

Figure 6: The magnetic (H-field) streamlines in the cross-section of a parallel-plate line.

 

Figure 7: The magnetic (H-field) streamlines in the cross-section of a coaxial line. The current in the shield is opposite to the current in the central wire.

 

Figure 8: The magnetic (H-field) streamlines in the cross-section of a microstrip line. The current in the strip is opposite to the current in the ground plate.