ON6ND's water analogy of LF antenna operation.
A coil can be represented a spring and a capacitor by a plate .
Fig 1 models a 1/4 wave antenna . The force input by the man is converted into a high velocity at V, by the L C line, made up of springs and plates, 500 metres long . When the man moves his arm up and down , the water will start waving .
Fig 2 models the short antenna as used by ON6ND. It is only 25 meters long but with a good coupling to the water because of the large plate, here brought to resonance by the spring L . The man applies force and the water will start waving .
Fig 3 short wire antenna with no top capacity. To have grip to the water we have long springs at the end ( top-cap of long wires ) brought to resonance by the spring L . But the springs are hanging in the mud and will act as a resistor, damping the resonance. The man is happy as he feels more power but the power is lost in the mud. If the mud was a steel plate the springs at the end would go in and out without loss of power. Spring L would need to be changed for resonance.
But no ground is perfect . So I think, if we have poor ground and a lot of trees in the neighbourhood, we are better with a smaller and higher top-cap, compensated with an extra coil ( coil close to the top-cap ) , instead of long wires pointed close to the ground. Keeping in mind that an LW antenna 25 meter high, is only 80 cm high if it was made for the 80 meter band . It is a miracle that we can hear each other. These are only ideas from a non-theoretical OM.... so don't believe me! But here it works.
This is Werner's high top capacity vertical.