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Example41 Frequency-Selective Reflector

General

  • Analyzed is a frequency-selective reflector that allows specific electromagnetic waves pass through.
     

  • The port size is large relative to the wavelength (about 10 times the wavelength).
     

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

Analysis Space

Item

Setting

Analysis Space

3D

Model Unit

mm

 

Analysis Condition

Item

Setting

Solver

Electromagnetic analysis [Hertz]

Analysis Type

Harmonic analysis

 

Tab

Setting Item

Setting

Mesh

Frequency-Dependent Meshing

Reference frequency: 77[GHz]

Select The conductor bodies thicker than the skin depth constitute the boundary condition

Harmonic Analysis

Sweep Type

Select “Linear step by division number”.

Sweep Setting

Minimum frequency: 40[GHz]

Maximum frequency: 90[GHz]

Division Number: 200

Frequency Sweep

Select Fast sweep

S-parameter tolerance: 1×10-3

 

Model

The model consists of a frequency-selective reflector and the air.

The dielectrics (Sub) are placed on the conductive plate (Metal) and encircled by curved slits.

 

 

Body Attributes and Materials

Body Number/Type

Body Attribute Name

Material Name

5, 30, 31, 32, 33, 34, 35, 36, 37/Solid

Sub

006_Glass_epoxy *

38/Solid

Air

000_Air *

39, 40, 41, 42, 43, 44, 45, 46, 47, 48/Solid

Metal

008_Cu (*)

* Available from the material DB

 

Boundary Condition

Boundary Condition Name/Topology

Tab

Boundary Condition Type

Setting

Port_001/Face

Electric

Port

Select Reference Impedance:
Use the characteristic impedance calculated from the port structure

 

Integral path

Set Path1

Port_002/Face

Electric

Port

Reference Impedance:
Select Use the characteristic impedance calculated from the port structure.

 

Integral path

Set Path1

EW/Face

Electric

Electric wall

 

Outer Boundary Condition

Electric

Magnetic wall

 

 

Set up Mesher/Solver

Setting Item

Setting

Frequency-Dependent Meshing

Reference frequency: 77[GHz]

Select The conductor bodies thicker than the skin depth constitute the boundary condition

 

Results

S-parameters are shown below. The transmission characteristic is observed at around 77GHz.

 

 

Shown below is the current density at 40GHz (transmission characteristic does not appear) and at 77GHz (transmission characteristic appears) on the frequency-selective reflector.

 

 

 

At 40GHz, the current is flowing in the entire area of the conductor whereas the current is concentrated near the slit at 77GHz.

Its value is large.

The electromagnetic field that causes the concentrated current near the slit is the resonant mode of the frequency-selective reflector. The resonant mode generates the transmission characteristic at a specific frequency.

 

The figures below show the electric fields at 40GHz and 77GHz. At 40GHz, the incident electromagnetic wave is blocked by the frequency-selective reflector and not transmitted.

At 77GHz, the electromagnetic wave is transmitted through the frequency-selective reflector.

For a clear comparison, the scale factor for drawing vectors is set to 10, and the maximum value is set to 3k[V/m].

 

 



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