I’ve been working on a golang wrapper library for libnecpp from nec++, a C library interface for a C++ rewrite of nec2c, which is a C rewrite of the original FORTRAN NEC2. That wrapper is in a pretty good state (although like so many projects not “done”, as such), and you can find it on github at https://github.com/ctdk/go-libnecpp. There are godocs for the library as well. Areas for future work include:
As a little learning exercise, I’ve written a calculator for Moxon antennas in Java as a command-line utility called moxoncalc. Given a frequency in megahertz and a wire size, moxoncalc will spit back to you the dimensions of a Moxon antenna designed to work at that frequency. By default it includes a diagram of what a Moxon looks like, but there are also optional formats with a short display that merely lists the dimensions of the sides and elements and a JSON rendering of the short display.