There are many published resources about the design and performance of NVIS antennas. Here are a few that we discussed recently on the air:
- The Cloud Warmer NVIS Beam - A nice article found by kb4xx.
- A Short Study of NVIS - A concise presentation of the design and performance. Includes antenna radiation patterns to show effects of various design choices.
- Some Notes on NVIS Antennas - This is a link to several very detailed articles by L. B. Cebik. A free web account provides access to a treasure trove of antenna articles by this author.