NEC File Import
Custom antennas can be imported as NEC decks, the standard text format used by antenna modelling tools such as 4nec2 and EZNEC. The Import NEC... button in the Antenna section loads a deck; Use built-in reverts to the selected built-in type.
Supported format
Plain NEC-2 style cards, coordinates in meters. Accepted file extensions: .nec, .ez, .txt.
| Card | Support |
|---|---|
| GW | Wire definition (tag, segments, endpoints, radius). A radius of 0 defaults to 1 mm. |
| GS | Scale factor, applied to all coordinates and radii. |
| GE | Geometry end; its ground flag is honoured. |
| GN | Ground description; mapped to the nearest of the simulator's ground categories (perfect, salt water, fresh water, good, average, very poor). |
| EX | Excitation; used to locate the feedpoint on the tagged wire. |
| FR | Design frequency. |
| EN | End of deck. |
| CM, CE | Comments, ignored. |
Not supported: lumped loads (LD), transmission line cards (TL) and other advanced cards are ignored. Antennas that depend on loading coils or line matching will therefore solve differently than in a full NEC package. A deck with no GW card is rejected.
Tips
- Model in a dedicated NEC tool, verify the pattern and impedance there, then export and import the deck.
- Keep the geometry moderate in size; extremely finely segmented models gain nothing and solve slowly.
- If no excitation card is present the feed defaults to the center of the first wire.