Maxwell SV Getting Started: A 2D Electrostatic Problem - LES

Getting Started: A 2D Electrostatic Problem
Create the Geometry
Now you are ready to draw the objects that make up the geometric model.
Keyboard Entry
In the following section, several of the points lie between grid points. You can position these points
in one of two ways:
• Change the grid spacing so that the object’s dimensions lie on grid points.
• Use “keyboard entry” — that is, enter the coordinates directly into the U and V fields in the
status bar.
If you change the grid spacing, the screen may become cluttered with too many tightly-spaced grid
points and make point selection difficult. Therefore, use keyboard entry to enter several of the
dimensions of the sample geometry.
Note To change the grid spacing, click the Window>Grid command.
To change the size of the problem region, click the Model>Drawing Size command.
Create the Substrate
The substrate consists of a simple rectangle on which the two rectangular microstrips will rest.
Draw a Rectangle
To create the rectangle to represent the substrate:
1. Click Object>Rectangle. After you do, the pointer changes to crosshairs.
2. Select the first corner of the substrate, the upper-left corner, as follows:
a. Move the crosshairs to the point on the grid where the u- and v- coordinates are (-20, 0).
Remember that the coordinates of the cursor’s current location are displayed in the U and
V fields in the status bar.
b. Click the point to select it.
3. To select the second corner of the substrate, use keyboard entry because -4, the v-coordinate,
lies between grid points. To specify the lower-right corner:
a. Double-click in the U field in the status bar.
b. Type 20, using the Backspace and Delete keys to correct typos.
c. Press Tab to move to the V field in the status bar. The value in the dU field changed. The
dU and dV fields display the values of the offset from the previous point.
d. Type –4.
4. To accept the point, press Return or click Enter in the status bar. After you do, the New
4-6 Creating the Model