Wire structures are made of linear PEC elements. These may consist of actual physical wires such as a dipole or loop antenna or a wireframe representation of a surface or solid object. In a wire structure, the unknown electric currents are one-dimensional. The integral equation is derived by forcing the tangential component of the electric field to vanish on the surface of the wire. This leads to the following simpler integral equation:
[[File:14_pocklingtons_tn.gif]][[files/images/manuals/emagware/emcube/modules/mom3d/an-overview-of-3-d-method-of-moments/pocklingtons-integral-equation-for-wire-structures/14_pocklingtons.gif|files/images/manuals/emagware/emcube/modules/mom3d/an-overview-of-3-d-method-of-moments/pocklingtons-integral-equation-for-wire-structures/14_pocklingtons.gif]]
where [[File:15_pocklingtons_tn.gif]][[files/images/manuals/emagware/emcube/modules/mom3d/an-overview-of-3-d-method-of-moments/pocklingtons-integral-equation-for-wire-structures/15_pocklingtons.gif|files/images/manuals/emagware/emcube/modules/mom3d/an-overview-of-3-d-method-of-moments/pocklingtons-integral-equation-for-wire-structures/15_pocklingtons.gif]] is the free space Green’s function, I(l) is the unknown linear current in the wire and C is the contour of the wire. [[File:16_pocklingtons_tn.gif]][[files/images/manuals/emagware/emcube/modules/mom3d/an-overview-of-3-d-method-of-moments/pocklingtons-integral-equation-for-wire-structures/16_pocklingtons.gif|files/images/manuals/emagware/emcube/modules/mom3d/an-overview-of-3-d-method-of-moments/pocklingtons-integral-equation-for-wire-structures/16_pocklingtons.gif]] and [[File:17_pocklingtons_tn.gif]][[files/images/manuals/emagware/emcube/modules/mom3d/an-overview-of-3-d-method-of-moments/pocklingtons-integral-equation-for-wire-structures/17_pocklingtons.gif|files/images/manuals/emagware/emcube/modules/mom3d/an-overview-of-3-d-method-of-moments/pocklingtons-integral-equation-for-wire-structures/17_pocklingtons.gif]] are the unit vectors along the wire contour. Note that [[File:15_pocklingtons_tn.gif]][[files/images/manuals/emagware/emcube/modules/mom3d/an-overview-of-3-d-method-of-moments/pocklingtons-integral-equation-for-wire-structures/15_pocklingtons.gif|files/images/manuals/emagware/emcube/modules/mom3d/an-overview-of-3-d-method-of-moments/pocklingtons-integral-equation-for-wire-structures/15_pocklingtons.gif]] has a singularity when r = r’, which must be either removed or avoided as will be explained later.
=== Discretization Of Wire Structures ===
You can connect a line object to a touching surface. To connect lines to surfaces and allow for current continuity, you must make sure that the box labeled '''Connect Lines to Touching Surfaces''' is checked in the '''Mesh Settings Dialog'''. If the end of a line lies on a flat surface, EM.CUBE will detect that and create the connection automatically. However, this may not always be the case if the surface is not flat and has curvature. In such cases, you have to specifically instruct EM.CUBE to enforce the connection. An example of this case is shown in the figure below.
[[File:wire_pic7_tn.png]][[files/images/manuals/emagware/emcube/modules/mom3d/mesh-generation/mesh-of-connected-objects/wire_pic7.png|files/images/manuals/emagware/emcube/modules/mom3d/mesh-generation/mesh-of-connected-objects/wire_pic7.png]] [[File:wire_pic8_tn.png]][[files/images/manuals/emagware/emcube/modules/mom3d/mesh-generation/mesh-of-connected-objects/wire_pic8.png|files/images/manuals/emagware/emcube/modules/mom3d/mesh-generation/mesh-of-connected-objects/wire_pic8.png]] [[File:wire_pic9_tn.png]][[files/images/manuals/emagware/emcube/modules/mom3d/mesh-generation/mesh-of-connected-objects/wire_pic9.png|files/images/manuals/emagware/emcube/modules/mom3d/mesh-generation/mesh-of-connected-objects/wire_pic9.png]]
The line object at the top of a PEC sphere and the structure's mesh without and with proximity mesh connection enforced.
NOTE: Computing the 3-D mono-static RCS may take an enormous amount of computation time.
[[File:wire_pic49.png]] [[File:wire_pic50_tn.png]][[files/images/manuals/emagware/emcube/modules/mom3d/visualizing-simulation-data/radar-cross-section/wire_pic50.png|files/images/manuals/emagware/emcube/modules/mom3d/visualizing-simulation-data/radar-cross-section/wire_pic50.png]]
The [[MoM3D Module]]'s RCS dialog and a half-wave wire connected to a metal plate illuminated by an obliquely incident plane wave.
[[File:wire_pic51_tn.png]][[files/images/manuals/emagware/emcube/modules/mom3d/visualizing-simulation-data/radar-cross-section/wire_pic51.png|files/images/manuals/emagware/emcube/modules/mom3d/visualizing-simulation-data/radar-cross-section/wire_pic51.png]] [[File:wire_pic52_tn.png]][[files/images/manuals/emagware/emcube/modules/mom3d/visualizing-simulation-data/radar-cross-section/wire_pic52.png|files/images/manuals/emagware/emcube/modules/mom3d/visualizing-simulation-data/radar-cross-section/wire_pic52.png]] [[File:wire_pic53_tn.png]][[files/images/manuals/emagware/emcube/modules/mom3d/visualizing-simulation-data/radar-cross-section/wire_pic53.png|files/images/manuals/emagware/emcube/modules/mom3d/visualizing-simulation-data/radar-cross-section/wire_pic53.png]]
The RCS of the wire-plate structure: (Left) σ<sub>θ</sub>, (Center) σ<sub>φ</sub> and (Right) total RCS..