[duckwheat]

That is a really good idea. My first thought was basically start with the tree, a drone's natural enemy, and amplify the stuff that makes it so dangerous to a drone - tiny sticks that are hard to see. Fishing line would pretty much accomplish that.

[JackFr]

https://en.m.wikipedia.org/wiki/Barrage_balloon

[King-Aaron]

I was thinking along these lines, but with more of a BallonFest '89 flavour to it

https://en.wikipedia.org/wiki/Balloonfest_%2786

[Animats]

Military bases in hostile territory may have to be surrounded and covered over by chain-link fence material on telephone poles.

[ridgeguy]

Kevlar thread. Less frequent replacement needed.