The ground system is a fundamental part of HF vertical antennas. because of this the design of ground systems have been a hot topic for the last 80 years or more. Unfortunately despite the intense interest a lot of very useful information has not found its way into amateur literature. The articles attached to this post are intended to help. The first article gives a good overview of the basics and reflects the accepted wisdom from BC antenna work, Ground system basics , 275 kb, QST July 2000. More posts on ground system design will be added shortly.