Ground mode vs air mode

[Mike(Mont)]

Dell Winders said air more goes farther than ground mode. Any gap in the ground will stop a ground signal. But ground signal is more accurate for pinpointing. I cam upon an interesting article on VLF ground radio. The guy calls it utilities assisted ground mode, meaning the signal follows buried pipelines, etc. Without that, the signal does not travel very far at all. I can't seem to get the link posted so you'll have to do a search Sub 9kHz Amateur Radio. Left column click on VLF Using Earth Mode