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# Example37Electromagnetic Field Correction

General

• The electromagnetic field of a minute dipole antenna is corrected by the function of ”Correct errors of the electromagnetic field originated in the open boundary”

• Unless specified in the list below, the default conditions will be applied.

### Analysis Condition

 Item Setting Solver Electromagnetic waves analysis [Hertz] Analysis Space 3D Analysis Type Harmonic analysis Unit mm Options Select Correct errors of the electromagnetic field originated in the open boundary

Harmonic Analysis tab and Open Boundary tab are set as follows.

 Tab Setting Item Setting Harmonic Analysis Sweep Type Single frequency Frequency 3×10^6[Hz] Sweep Setting Discrete sweep Input 1.0[W] Open Boundary Type Absorbing boundary Order of Absorbing Boundary 1st degree

### Graphical Object

A minute dipole antenna consists of PEC and port. It is surrounded by an ambient air. A body named “Correction” is a domain for correcting the electromagnetic field. To shorten the calculation time, the domain for correction is limited.

There is another air box surrounding the ambient air. When an open boundary condition is set on the outermost area of the analysis domain, the accuracy of the electromagnetic field near the open boundary condition tends to be degraded. Therefore, for the better look, another air box is created to hide the area with low accuracy.

Whole model Antenna

Model viewed from X axis direction

### Body Attributes and Materials

 Body Number/Type Body Attribute Name Material Name 45,46,69,71,75,76/Solid PEC PEC 78,79,81/Sheet AIR AIR 80/Solid Correction AIR 47,70,77/Sheet Imprinting body

* Available from the Material DB

 Body Number/Type Body Attribute Name Material Name Mesh Size 45,46,69,71,75,76/Solid PEC PEC 0.5 47,70,77/Sheet Imprinting body 0.5

 Body Attribute Name Analysis Domain Correction Select “Correct errors of the electromagnetic field originated in the open boundary”

• Correction is executed only for the bodies with this option selected.

### Boundary Condition

 Boundary Condition Name/Topology Tab Boundary Condition Type Setting PORT/Face Electric Port Current port Outer Boundary Condition Electric Open Boundary Select on the open boundary tab of the analysis condition setting.

### Set up Mesher/Solver

 Setting Item Setting Frequency-Dependent Meshing Reference frequency: 300×10^6[Hz] Select “The conductor bodies thicker than the skin depth constitute the boundary condition.”

### Results

You can view the results fields.

Go to Results tab > Display > Solver, and select “Electromagnetic waves correction field”

The field types are as follows.

 Electric field [V/m] original Electric field before correction. It is the same electric field as displayed in the electromagnetic waves analysis. Depending on the display method, they don’t necessarily match. Electric field [V/m] data for correction Electric field for correction. The larger the value, the greater the reflection on the open boundary. Electric field [V/m] after correction Original data and corrected data of the electric field are added. Magnetic field [A/m] original Magnetic field before correction. It is the same magnetic field as displayed in the electromagnetic waves analysis. Depending on the display method, they don’t necessarily match. Magnetic field [A/m] data for correction Magnetic field field for correction. The larger the value, the greater the reflection on the open boundary. Magnetic field [A/m] after correction Original data and corrected data of the magnetic field are added.

The left diagram below is based on the conditions listed below. The gradation contour diagram is displayed with bodies “AIR” and “PEC” hidden because the corrected body in this example is body “Correction” only.

 Electromagnetic waves correction field 0.300000GHｚ Electric field [V/m] original Magnitude 270° Log

The right diagram below is obtained by changing “Electric field [V/m] original” to “Electric field [V/m] after correction”.

The color scale is set from 3ｘ105[V/m] to 3×104[V/m]. This setting is needed to draw the diagram representing overall distributions well.

While the lower left diagram shows the field pulled to the boundary unnaturally in the upper and lower areas of the dipole antenna, the lower right diagram shows the natural field after the correction. The influence of the boundary is not observed.

The correction has been successfully executed.

For your information, the diagrams at the top of this page are drawn with the section view and the line contour.

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