not every one will agree w/me on this but I'll put it out there anyway. in my 30 yrs of doing RF I have found that grounding an antenna just makes it a better "target". I have 6 major sites in NYC all above 400' asl none have any real antenna grounding system and I can count on one hand how many times I have had to replace an antenna from a hit. on the other hand there is a customers site that was properly grounded and every 2-3yrs i have to go change an exploded cigar, not too fun. now towers are a completely different animal altogether. again this has been my experience in the north east, where you are in FL is probably a completely different matter. for a control station w/antenna 15' above the roof line I wouldn't sweat it too much. what in the immediate area will be higher than that,light pole ,phone pole,ect..... you get where I'm goin' w/this. some things to look at. https://www.tessco.com/products/displayProductInfo.do?sku=68433&eventPage=1 I may have some of these around, if you want one let me know I'll send one down. you can pick up an 8' ground rod at home depot.