One-Step Construction of Complicated Structures
Some pre-defined structures are built into the MGRID. All these pre-defined structures are created by selecting the menu items in Entity menu on MGRID. The pre-defined structures are discussed in this appendix. Shown in the figures are the meanings of the parameters. Please compare the figures to the dialog for better understanding of the parameters. We welcome suggestions on building the Entity library.
1. Rectangle:
The last entered vertex, if there is any, will be set as the reference point. The reference point can be chosen as the center, lower left corner, lower right corner, upper left corner or upper right corner. Please be careful that the actual reference point location, the length and the width are related to the rotation angle. If the rotation angle is 90 degrees, the Length will become Width, and the lower left corner of the 90 degree rotation is the lower right corner of the 0 degree rotation.
Figure I.1 The Rectangle entity and its parameters.
2. Symmetrical T-Junction:
The last entered vertex, if there is any, will be set as the center. A user can change the Vertical Arm’s Length and Width, Horizontal Arm’s Length and Width. The Chamfer Size takes the value between [0,1).
Figure I.2 The Symmetrical T-Junction entity and its parameters.
3. Symmetrical Y-Junction:
The last entered vertex, if there is any, will be set as the center. A user can choose the Arm Length from Center and Arm Width. The Start Angle defines the angle of the 1starm.
Figure I.3 The Symmetrical Y-Junction entity and its parameters.
4. Symmetrical Step:
The last entered vertex, if there is any, will be set as the center.
Figure I.4 The Symmetrical Step entity and its parameters.
5. Chamfered Bend:
The last entered vertex, if there is any, will be set as the center, or the inner corner of the bend. A user can define the length and width of the arms. The Rotation Angle defines the 1st arm’s angle. The Chamfer Size takes value from 0 to 1. When it is 0, there is not chamfer. When it is 1, the smallest width for the bend is 0.
Figure I.5 The Chamfered Bend entity and its parameters.
6. Circle:
The last entered vertex, if there is any, will be set as the center. The starting point is not measured in degrees. It is measured in segments. For example, if we choose the Number of Segments for Circle = 16, each segment corresponds to 90/4 = 22.5 degrees. If we specify the starting point as 1.5, then the actual angle is 22.5 by 3 / 2 = 33.75 degrees.
Figure I.6 The Circle entity and its parameters.
7. Circular Sector:
The last entered vertex, if there is any, will be set as the center of a corresponding circle.
Figure I.7 The Circular Sector entity and its parameters
8. Ring:
The last entered vertex, if there is any, will be set as the center of a corresponding circle. Also there are options for slightly different shapes.
Figure I.8 The Ring entity and its parameters.
9. Annular Sector:
The last entered vertex, if there is any, will be set as the center of a corresponding circle.
Figure I.9 The Annular Sector entity and its parameters.
10. Conical Tube:
The center parameters in the dialog are the parameters of the center of the initial point. The cross-section of the initial point is a circle and the starting point is of the same definition of the circle entity.
Figure I.10 Conical Tube entity and its parameters.
11. Tube Bend:
Following are the definitions of the parameters:
Segments for Tube Circle: The number of segments for the tube only. It is not for the bend.
Tube Radius: The radius of the tube.
Starting Point: The starting point of the tube.
Center Coordinates: That is the center of the bend.
Section Index: The location of the 90-degree bend in the quadrant. Section Index = 0 means it is in the first quadrant, and so on.
Segments for Bend: The number of segments for the 90-degree bend.
Bend Radius: The radius of the tube bend.
Figure I.11 The Tube Bend and its parameters.
12. Sphere:
The Starting Point is for the horizontal segments only. For the other direction, the segment always starts from the axis direction.
Figure I.12 Sphere entity and its parameters.
13. Cylindrical Helix:
There are 2 dialogs for it. The first dialog is for the wire parameters: the segments for the wire circle and the radius of the wire. The center coordinates are for the starting point.
The second dialog is for the helix parameters: the segments for each turn, the total segments, helix length, helix radius, start vertical wire length, end vertical wire length, and start angle. The start angle is for the connection between the end of the start vertical wire and the start of the first segment of the helix. The angle of the connection is the start angle.
It should be pointed out that the total segments could take negative number. If it is a positive integer, the helix turns in the counter clockwise direction. If it is a negative integer, the helix turns in the clockwise direction.
Figure I.13 Cylindrical Helix entity and its parameters.
14. Conical Helix:
There are 2 dialogs for it. The first dialog is for the wire parameters: the segments for the wire circle and the radius of the wire. The center coordinates are for the starting point.
The second dialog is for the helix parameters: the segments for each turn, the total segments, exponential constant, initial radius, conical angle, feed line length and start angle.
The cylindrical radius at each angle is R = R0 EXP[ A (j - j0)], where R0 is the initial radius, A is the exponential constant, j is the angle in gradient, j0 is the start angle in gradient.
The start angle is for the connection between the end of the feed line and the start of the first segment of the helix. The angle of the connection is the start angle.
The total segments can take negative number. If it is a positive integer, the helix turns in the counter clockwise direction. If it is a negative integer, the helix turns in the clockwise direction.
Figure I.14 Conical helix and its parameters.
15. Circular Hole in Square:
The Circular Hole in Square does not dig a circular hole on a polygon. It just builds the shape of a circular hole in a square. To build a circular or arbitrary hole on an existing polygon, you need to use the Dig Hole from Selected Polygons in Adv Editmenu.
The last entered vertex, if there is any, will be set as the center of the circle.
Figure I.15 Circular Hole in Square entity and its parameters.
16. Circular Hole in Rectangle:
The Circular Hole in Rectangle also does not dig a circular hole on a polygon. It just builds the shape of a circular hole in a rectangle. To build a circular or arbitrary hole on an existing polygon, you need to use the Dig Hole from Selected Polygons in Adv Edit menu.
The last entered vertex, if there is any, will be set as the center of the circle. The parameters are similar to the circle. The circle and the rectangle are always co-centered. The additional parameters are the rectangle length and width.
Figure I.16 The Circular Hole in Rectangle entity and its parameters.
17. Rectangular Spiral:
Each quarter is a rectangular corner. 4 quarters form a turn. Starting point index is to identify where the starting point is. When the starting point index is 0, the starting angle is at j = 0 degree. When the starting point index is 1, the starting angle is at j = 90 degrees. The Number of Quarters can take negative value for opposite turning direction.
Figure I.17 Rectangular Spiral entity with starting point index of 1, and 18 quarters.
18. Octagonal Spiral:
The last entered vertex, if there is any, will be set as the center. The size of the spiral is decided by the number of quarters. The starting point is similarly defined as the rectangular spiral.
Figure I.18 The Octagonal Spiral entity and its parameters.
19. Circular Spiral:
There are a few options for the circular spiral. The starting point can be From Inner Radius or From Outer Radius. The corner style can be smooth change or abrupt change. The last option is whether you want to guarantee the trace width or the vertex location. Because we approximate the circular spiral with segments, we can guarantee either the trace and gap widths or that the locations of the vertices are on the spiral.
Smooth Change Corner Style Abrupt Change Corner Style
Figure I.19 Circular Spiral entity and its parameters.
20. Interdigital Capacitor:
The last entered vertex, if there is any, will be set as the center.
Figure I.20 The Interdigital Capacitor entity and its parameters.
21. MIM Capacitor:
The last entered vertex, if there is any, will be set as the center. The meshing between the top and bottom plates is aligned. Also, the user has the option to create a circular or rectangular via on the bottom plate.
Figure I.21 The MIM Capacitor entity and its parameters.
22. Probe-Feed to Patch:
It is an automatic way to build a Vertical Localized port. It is very useful for constructing probe-fed patch antennas. However, its application is more than probe-fed patch antennas. The probe will be modeled at least as a rectangular tube (with Number of Segments for Quarter = 1). You should make sure there is metal on the start z-coordinate and the end z-coordinate. Metal means that it must be some polygons representing metallic structures or a ground plane defined as substrate. The Positive Level and the Negative Level can be at the start z-coordinate or end z-coordinate. The Positive Level should be different from the Negative Level. However, the difference should be very small compared to the waveguide wavelength. For probe-fed patch antenna, it is suggested that the Negative Level should be located at the Start Z-coordinate and the difference between the Positive Level and Negative Level should be about 1% of the probe length. The Positive Level can also be smaller than the Negative Level.
The last entered vertex, if there is any, will be set as the location of the probe.
Figure I. 22 Probe-Feed to Patch entity and its parameters.
23. Conical Via:
The Conical Via is similar to the Conical Tube entity. The difference is that Conical Via will make the electrical connection between the conical tube and the metal at the Start Z-Coordinate and End Z-Coordinate, if there is any, as it does for the Probe-Feed to Patch entity.
If you enter 1 vertex before you select the Conical Via menu item, the location of the vertex will be used for the center of the conical via end. If you entered more than 1 vertex before you select the Conical Via menu item, the location of the second last vertex will be used for the default center of the conical via end. The distance between the second last vertex and the first last vertex will be used for the default value of the radius.
Figure I. 23 The Conical Via entity and its parameters.
Many of the entities can be constructed in either of the x, y and z-direction. It should be pointed out that the there may not be an overlapping checking for the pre-defined structures. Please perform an overlapping checking or cutting overlapping polygons.
Documented in this appendix may not a complete list of the entity objects in the software. If you have any suggestion on any entity you would like to build into MGRID, please feel free to report to us. We will try our best to construct it for your convenience.
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