I have tested several vertical antennas, feed against buried radials 0.1 lambda long. The wire vertical component or stacked pipes or even the real tower on the hill...
I have tested also very tall (>100 ft) tree at the edge of my property vertical with moderate results on Top Band. I’m thinking of using the tree to support the vertical component, and going to an elevated radial system.
Also the grounded half loop with 30/20m vertical sections and 80m phasing elements i tested for several years including the 16x 0.1 lambda long radials laying on the ground.
This is an interesting read about elevated radials:
(Thanks to Rudy, N6LF for that article...)
73 - Petr, OK1RP