Generation of the NEC2 input file

• Fixed length data fields. All numbers are separated by spaces, where all integers occupy fields three to five characters long, and floating point numbers occupy 10 character long fields. This is the format documented in the user guide [#NEC2-user##1###].
• Variable length data fields. All numbers are separated by commas. A number of newer versions of NEC2 also support this format.

WIREGRID also provides for the generation of control statements which allow maximum coupling computation between voltage sources, and radiation pattern generation at specified frequencies. Only wire segments belonging to major elements defined by <#253#>two<#253#> nodes may be excited for this purpose. (Of course, the experienced user can edit the NEC2 data file created by WIREGRID to define more complex antennas). Furthermore, the radiation pattern cards generated are only for cross sections defined by angles of constant azimuth or elevation angles of the full three dimensional patterns. Since it is fairly easy to enter the control statements into the NEC2 input file by hand, only these very common type of requests are catered for by WIREGRID.

Any additional command lines or alterations to the geometry data may be added afterwards, with the user's editor of choice. For this purpose, the following information on the structure of the geometry data section is important:

• Each tag number in the file refers to the number of the major element wherein the wire segment is located. This means that wire segments belonging to major elements defined by more than two major nodes do not have unique tag numbers, and cannot be referred to by the control statements at the end of the file, unless the tag number is changed by the user afterwards. This is also the reason why WIREGRID only allows excitation of segments in two-node major elements in its control statement generation options.

• Geometry data for the polygonal boundaries (yellow²) between the major elements are entered first into the file, starting with the boundaries of major element number 0, and then the two node elements are added.

• This is followed by data statements describing the internal meshes (where relevant). These statements are divided into sets for each polygonal major element, starting with the element with the lowest tag number. In addition, the internal mesh data statements for each polygonal major element are subdivided into a subset of statements describing long, straight, segmented wire sections (red), and a subset describing short, single segment wire sections (blue).