When small UAV pilots fly in accordance with FAA regulations, they should never have to worry about the technologies in this article. That said, a number of methods have been developed to help the military and law enforcement engage drones that are perceived as a threat. Among them are the technologies stated below. There are probably other technologies as well . . .

As mentioned in my last blog, Remote Identification of Aerial Drones, the FAA will soon require all drones in the U.S. airspace to implement new technologies that will enable identification of the drone and its owner/pilot.

Counter-Drone Technologies Include:

DroneShield offers several models that employ electronic countermeasures (radio frequency methods) to down aerial drones at ranges up to 1.25 miles.
https://www.droneshield.com/

The Dutch firm Delft Dynamics has developed an anti-drone drone called the DroneCatcher. Their medium-sized drone can lock onto a smaller UAV in the air and take it down with a net.
https://dronecatcher.nl/

A ground-based netting system has been developed by the UK firm Open Works that employs a bazooka-like gun to take down a small UAV at ranges up to 330 feet.
https://openworksengineering.com/skywall-patrol/

Lockheed-Martin developed their Athena laser-based air defense system for small targets, which can destroy small aerial drones in flight. Built for military applications, variations of this technology could find their way into domestic law enforcement.
https://www.lockheedmartin.com/en-us/products/athena.html

Drone Defense, a UK company, offers their RF-based system called the Paladyne E1000MP, which disables drone communications. Based on its description on the company’s web site, the targeted drone is kept out of a sensitive area but not taken down.
https://www.dronedefence.co.uk/

Conclusion

The popularity of aerial drones continues to grow, and with it comes the possibility of their unlawful usage. As a result, counter-drone technologies are quickly developing. For now, it seems these technologies are not available to the general public, but are almost certainly finding their way into military installations, prisons, critical infrastructure, and other controlled airspace. Small UAV pilots should be aware of them if their operations take place in or near sensitive areas.