Results
Magnetic Flux Density
Again check the default plot for any modeling errors. Note that the magnetic flux density inside the copper winding is not computed as this domain was excluded.
Plot the surface current distribution at the lowest frequency solved for. This frequency is below resonance and the device is of an inductive nature.
Datasets
1
In the Model Builder under Results > Datasets, right-click Study 2/Solution 3  and choose Duplicate .
2
Right-click Study 2/Solution 3 (6) and choose Selection.
3
Go to the Settings window for Selection. Under Geometric Entity Selection from the Geometric entity level list, choose Boundary.
4
From the Selection list, choose Conductor Boundaries.
Surface Current Density
1
In the Results toolbar click 3D Plot Group . In the Settings window, type Surface Current Density in the Label text field.
2
Go to the Settings window for 3D Plot Group. Under Data from the Dataset list, choose Study 2/Solution 3 (6).
3
From the Parameter value (freq (MHz)) list, choose 1.
4
Right-click Surface Current Density and choose Surface .
5
Go to the Settings window for Surface. In the upper-right corner of the Expression section, click Replace Expression .
6
From the menu, choose Model > Component 1 > Magnetic Fields > Currents and charge > mf.normJs - Surface current density norm (when you know the variable name, as in this exercise, you can also enter mf.normJs directly in the Expression text field).
7
Click the Plot button.
The plot shows the surface current distribution and should match this figure.
Change to the highest frequency solved for and compare the results. Finish the modeling session by plotting the real and imaginary parts of the coil impedance.
Coil Impedance
1
In the Results toolbar click 1D Plot Group .
2
In the Settings window for 1D Plot Group, type Coil Impedance in the Label text field.
3
Locate the Data section, select Study 2/Solution 3 (5) from the Dataset list.
4
Locate the Plot Settings section, select the Two y-axes checkbox.
5
Right-click Coil Impedance and choose Global .
6
Go to the Settings window for Global. Under y-Axis Data in the Expression column, enter real(mf.Zport_1). In the Description column, enter Real part of impedance.
Note: In general, you can click the Replace Expression to see what variables are available in the predefined lists. In this case, you can enter the information directly into the table.
7
Right-click Coil Impedance and choose Global again to add a plot for the imaginary part of impedance. Alternatively you can duplicate the previous node.
8
Go to the Settings window for Global. Under y-Axis, select the Plot on secondary y axis checkbox.
9
Under y-Axis Data in the Expression column, enter imag(mf.Zport_1). In the Description column, enter Imaginary part of impedance.
10
Click the Plot button.
The real (resistive) part of the coil impedance peaks when passing through the resonance frequency. The imaginary (reactive) part of the coil impedance changes sign when passing through the resonance frequency, going from inductive to capacitive.
The resistive part of the coil impedance peaks at the resonance frequency. The reactive part of the coil impedance approaches the one given by the static inductance value at low frequency. With increasing frequency, the quantity increases and then changes sign at the resonance. This happens since the inductor is entering a capacitive regime where the net current is dominated by displacement currents flowing perpendicularly to the coil windings.
As a final step, pick one of the plots to use as a model thumbnail. This selects a nice-looking 3D figure for the graphics window.
1
In the Model Builder under Results click |B| and Coil Direction .
2
Click the Root node (the first node in the model tree). In the Settings window for Root under Presentation > Thumbnail, click Set from Graphics Window.
Make adjustments to the image in the Graphics window using the toolbar buttons until the image is one that is suitable to your purposes.