The link below leads to NEC-4 plots of the r-f losses for three configurations of buried conductors used in Part 15 AM antenna systems, for various earth conductivities at the antenna site.
The link below leads to NEC-4 plots of the r-f losses for three configurations of buried conductors used in Part 15 AM antenna systems, for various earth conductivities at the antenna site.
This post was prompted by PhilB's comments in the Part15us thread "RF Current Transformer for Antenna Tuning."
From those images we learn that an 8-foot ground rod is better than no ground at all, but that more than 8x 6-meter radials gets better and better, the more there are.
On this subject of ground connectivity/conductivity loss I have a few additional questions:
Does the "topping" make a difference in the result? Topping is the surface layer, be it grass, gravel, blacktop, etc.
Can additives be mixed with the dirt, be they chemical, biological, mineral, in order to improve the local ground conductivity?
Utility companies use a chemical to improve the ground conductivity, just not sure what it's called because you can get it at any hardware store.
But even simple watering of the area where your ground system is will vastly improve the ground conductivity.
As to "toppings", never seen an MW site sitting on a blacktop. Always been an open field and firmly planted into dirt with nothing but dirt and grass/weeds/brush growing here and there. Maybe a rabbit or two, desert rat and a few rattlers. But blacktop...that's a new one for me.
RFB