EZNEC is a popular antenna modelling program created by W7EL which is based on the "Numerical Electromagnetics Code" or NEC. With a NEC based antenna modelling program it is possible to design antennas by modelling their geometry and connections, and then simulating parameters like radiation pattern gain and VSWR. You can also determine the effects of height, roof angles, nearby objects and more.
Originally the pricing was $99 for EZNEC, $149 for EZNEC+, $525 for EZNEC Pro/2 and $675 for EZNEC Pro/4. W7EL is retiring and from Jan 1 2022 EZNEC Pro/2 and EZNEC+ will be made free, and EZNEC Pro/4 will be discontinued. The source code will not be released, and no support will be provided.
If you're after a free NEC based antenna modeler today, 4NEC2 is a similar program that is already free. There is also the recently released and more modern CENOS, which is free for hobbyist use.
4NEC2 is a freeware antenna simulation software program. The program can be used to model an antenna, and then determine through simulation properties such as the radiation pattern and SWR of the modelled antenna. It is very useful for those designing home made antennas for their RTL-SDR or other radio, or for those just trying to understand how antennas work.
4NEC2 can be a complicated piece of software and to get the most out of it a guide is needed. We’ve recently been informed that Mark Schoonover KA6WKE, is writing an eBook guide on this topic. His guide is currently only 20% complete, but a free sample of his book in its current state can be downloaded from leanpub. The guide already shows what the main windows of 4NEC2 do, and shows you how to model and simulate a simple dipole antenna.