Electrostatic Analysis of an Assembly

The following figure depicts four conductors on a ground plane. Conductors 1 and 2 are strips. Conductors 3 and 4 are solids. The structure has two substrate beds: Substrate 1 lies between the strip conductors and the ground plane. Substrate 2 lies between the strip conductors and the solid conductors.

Dimension Information

• The dimensions (in cm) in the X-Z plane are depicted in the figure.
• Depth in the Y direction = 1.00 cm.
• Relative permittivity of substrate 1 = er1 = 10.5 (Duroid 6010.2).
• Relative permittivity of substrate 2 = er2 = 2.33 (Cu Clad 233).

The structure is an open-region. Thus the air-region surrounding the structure must be meshed. Since it is an electrostatic problem, it is not necessary to apply any absorbing or asymptotic boundary condition on the outer boundary, i.e. the boundary condition is enforced in the weak sense.

Constructing the Model

COSMOSDesignSTAR supports many CAD systems. This model's geometry was created in SolidWorks. Since there are different materials involved, the problem must be modeled as an assembly. The assembly contains three components as follows:

• The first part is Epsilonr1, which is the lower substrate.
• The second part is Epsilonr2, which is the upper substrate.
• The third part is the air surrounding the structure.

The assembly was modeled to include 5.00 cm layers of air (from the upper conductors) in the X-direction and 10.00 cm (from the top edge) in the Z-direction. As a result, the dimensions of the surrounding box are 18.00 cm in the X-direction, 1.00 cm in the Y-direction, and 13.10 cm in the Z-direction.

Since the two strips and solids are perfect conductors, they are modeled as voids with a conducting boundary condition assigned to their boundaries.

EMS Results

• Electric Field Intensity

  

• Electric Field Section plot

  

• Displacement Field Intensity

  

• Capacitance Calculation