Attributes of Grids and Surfaces

The Attributes tab in the Draw dialog box allows you to define how a geometric shape (like a Plate, Disc, or Sphere) is mathematically represented in the simulation. While the shapes differ, they all share the same attribute logic.

Defining the Structure: Wire Grid vs. Solid Surface

The most critical choice is made in the Cross-Section field (Fig. 1). This setting determines whether the object has “holes” or is a continuous sheet of metal.

• Wire Grid: Select Circular cross-section and set a radius ($a > 0$). This creates a mesh of cylindrical wires with open gaps between them.
• Solid Surface: Select Flat or Rectangular cross-section. AN-SOF automatically adjusts the width of these “strip” wires so they touch edge-to-edge, covering the surface completely with no gaps.
  • Flat: Represents a surface with zero physical thickness.
  • Rectangular: Allows you to specify a physical thickness for the metal sheet.

Number of Facets

Facets are the “building blocks” of the grid or surface. They are typically quadrilaterals formed by four interconnected wires.

• Grid Arrangement: You define facets as a grid (e.g., $10 \times 10$ for a Plate or $6 \times 12$ for a Disk).
• Automatic Calculation (Patch only): Setting facets to 0x0 for a Patch allows AN-SOF to auto-calculate the density based on the highest frequency (targeting 10 segments per wavelength).

Segments per Wire

This defines how many computational segments exist on each individual wire that makes up the facets.

• Manual Control: Set a specific integer for custom precision.
• Automatic: Set to zero to let AN-SOF apply the 10-segments-per-wavelength rule.
• Note on Patches: The Patch tool does not have this option because its facets are always composed of single-segment wires.

Individual vs. Mass Editing

Once a grid or surface is created, you have two ways to modify it:

• Mass Edit: Refer to Modifying a Grid/Surface to change the attributes of the entire object at once (e.g., changing the radius of all wires in a mesh).
• Individual Edit: You can right-click any single wire within the mesh to change its specific properties or position without affecting the rest of the grid.