You can get a demo copy of EZNEC from the author's website ( Google W7EL). It it quite sufficient for basic antennas. The ARRL also has a version on CD with their 22 edition of the ARRL Antenna book. If you have never modelled antennas before, I highly recommend the beginners program that is offered from the ARRL, I cannot make a copy of my EZNEC programs as they are copyrighted. There are other antenna modelling software programs besides EZNEC, MMANA is one, free for the download and it will even convert EZ files so the model will run on MMANA......I hope you like coordinate geometry !!!!