Since we cannot change our ground conductivity, is there a number on the chart where it's not worth installing a typical 80m 4 square (with buried radials)? It looks like many of the big New England contest stations are in the 1-2 millimhos/meter zone. John KK9A/4 Brian Beezley k6sti wrote: Try this: http://ham-radio.com/k6sti/FCCMapArticle.pdf Brian