A multi-threaded EM tool based on NEC2 to model antenna radiation patterns

Xnec2c is a high-performance multi-threaded electromagnetic simulation package to model antenna near- and far-field radiation patterns for Linux and UNIX operating systems.
The original FORTRAN version of NEC2 was ported to C by Neoklis Kyriazis, 5B4AZ and released as nec2c.
Later he wrote xnec2c, a graphical interface for ease of use with many more features.