There are drones that are powered with power tether from the ground station, and such drones can be airborne 24/7, not only 20 minutes when using batteries.
I'm very interested to reverse-engineer how such power tethers could be constructed. Such system needs to usually be able to transfer around 500 W and 30 meters (100 feet) in length.
Main restriction for designing such system is weight of tether cable which should be as light as possible, ideally less then 1 kg (2.2 pounds).
Which approach is better - high-voltage DC voltage or high-voltage AC?
Also by using high voltage we have two drawbacks - operator safety and cable insulation weight increase.
When using AC we can also choose to go with very high frequencies, is there any benefit in using high frequency and get better power transfer?
So what would be ideal combination of voltage to transfer high power on light and thin cable?
is there any special type of cable that would allow for high power transfer but keep weight low?
Example of such system: https://www.youtube.com/watch?v=VHwEb86s2SI