基于ADS的微带天线的设计与仿真(10)

Defining Mesh Parameters for a Layout Layer

You can define mesh parameters that affect the objects on a single layout layer. If you have global parameters set, they will not be used where mesh parameters are defined for a layout layer. To set up layout layer parameters: 1. Choose Momentum > Mesh > Setup. 2. Click the Layer tab.

3. From the Layout Layer list, select the metallization layer that you want to specify mesh parameters for.

4. Enter the Mesh Density - cells/wavelength. This value, along with the wavelength of the frequency specified in the Frequency field, will be used to determine the density of the mesh. (Recall that the frequency is a global parameter).

The relationship between wavelength and cells per wavelength is best described by example. If the portion of the circuit on this layer is 2 wavelengths long and the number of cells per wavelength is 20, the length of the circuit on this layer will be divided into 40 cells. For more information, refer to Adjusting Mesh Density.

5. Enable Edge Mesh to add a relatively dense mesh along the edges of the objects on this layer. Since most current flows along the edges of objects, the edge mesh can improve the accuracy and speed of a simulation.

If want the edge mesh to be sized automatically, leave the Edge Width field blank. Otherwise, specify the edge width and select the units. For more information about the edge mesh, refer to About the Edge Mesh.

6. Enable Transmission Line Mesh to specify the number of cells along the width of the geometry on this layer. It is most useful for circuits with straight-line geometry.

Enter the number of cells that the width will be divided into in the Number of Cells Wide field. This will be the total number of cells along the width of the circuit on this layer. For more information about the transmission mesh, refer to About the Transmission Line Mesh. 7. If you want to change the settings for the selected layer, click Reset to return to default values or Clear to erase your settings.

8. Select another layer and repeat these steps for setting the mesh parameters. 9. Click OK to accept the mesh parameters for the layers.

Defining Mesh Parameters for an Object

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You can define mesh parameters that affect a single object. If you have global or layout layer parameters set, they will not be used where mesh parameters are defined for an object.

To set up object parameters:

1. Choose Momentum > Mesh > Setup. 2. Click the Primitive tab.

3. In the Layout window, select the object that you want to specify mesh parameters for. 4. Enter the Mesh Density - cells/wavelength. This value, along with the wavelength of the frequency specified in the Frequency field, will be used to determine the density of the mesh. (Recall that the frequency is a global parameter).

The relationship between wavelength and cells per wavelength is best described by example. If the object is 1/2 wavelengths long and the number of cells per wavelength is 20, the length of the object will be divided into 10 cells. For more information, refer to Adjusting Mesh Density.

5. Enable Edge Mesh to add a relatively dense mesh along the edges of the object. Since most current flows along the edges of objects, the edge mesh can improve the accuracy and speed of a simulation.

If want the edge mesh to be sized automatically, leave the Edge Width field blank. Otherwise, specify the edge width and select the units. For more information about the edge mesh, refer to About the Edge Mesh.

6. Enable Transmission Line Mesh to specify the number of cells along the width of the object. It is most useful for circuits with straight-line geometry.

Enter the number of cells that the width will be divided into in the Number of Cells Wide field. This will be the total number of cells along the width of the object. For more information about the transmission mesh, refer to About the Transmission Line Mesh. 7. If you want to change the settings for the selected object, click Reset to return to default values or Clear to erase your settings.

8. Select another object and repeat these steps for setting the mesh parameters.

9.

Click OK to accept the mesh parameters for the objects.

Seeding an Object

For the majority of circuits, it is not necessary to seed an object, and it is not recommended because all internal mesh processes will be skipped. If an object is seeded incorrectly, an inefficient

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mesh will result, affecting simulation speed and accuracy. You should have a good understanding of electromagnetics and computational geometry to be able to use this meshing feature efficiently.

Primitive seeding enables you to specify the exact number of cells to be applied to a geometry:

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Horizontally, across the o,u-axis Vertically, from point V to the o,u-axis

The example below illustrates the position of the o,u-axis and the position of point V

with respect to OU on a simple shape. Regardless of the object seeding is applied to, OV must be perpendicular to OU in order to create a correct mesh. This mesh was defined to be three cells wide along the o,u-axis, and five cells high.

To seed a primitive:

1. Determine the method for entering mesh coordinates. You can:

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Type coordinates directly into the Coordinate Entry dialog box Select coordinates by clicking on objects in the Layout window

If you choose select coordinates on the object, make sure that the vertex snap mode is on, and check your other snap modes to make sure that you can completely align the mesh with the structure. If snap modes are on when you select a coordinate, the system will snap to the nearest point that satisfies an enabled snap mod …… 此处隐藏：6446字，全部文档内容请下载后查看。喜欢就下载吧 ……