What are Anti Drone Systems?

Two IED blasts shook the IAF (Indian Air Force) base in Jammu in the early hours of 27^th June, when two drones dropped high-grade explosives which damaged a building's roof and also injured two IAF soldiers.
This is the first drone-based terror strike on Indian soil, and it portends a dark future in which Unmanned Aerial Systems (UAS), autonomous weapons systems, and robotic warriors will be used as new forms of sabotage and violence.
In 2018, Syrian rebels used homemade drones to target Russian military positions in Syria, and Venezuelan President Nicolas Maduro narrowly evaded an assassination attempt by a GPS-guided drone attack the same year. It gained even more traction in 2019 after Houthi rebels in Yemen claimed responsibility for targeting two important Saudi oil facilities.

Unwanted drones and unmanned aerial vehicles are detected and/or intercepted using anti-drone devices (UAVs). The development of low-cost UAVs has led to an increase in occurrences using hostile drones, which may be used to lay bombs, smuggle contraband, or gather intelligence on sensitive assets.
Anti-drone equipment is used to defend airports, important infrastructure, big public spaces like stadiums, as well as military installations, and war sites.

UAVs can also be detected using radar detection. Traditional military and aviation radar systems, which are built to detect large aircraft, may struggle to detect or discriminate smaller drones from other objects, such as birds. They might also have trouble dealing with drones that move slowly or hover.
Depending on the range, size of the protective zone, number of simultaneous targets to track, and ability to deal with the ambient interference, modern anti-drone radar systems may use a variety of radar technologies, such as ESA (i.e. Electronically Scanned Array), Staring radar, and Micro-Doppler. They provide 3D airspace tracking & use advanced signal processing techniques in order to detect and identify drones with pinpoint accuracy.
Multi-sensor anti-drone systems will combine several sensor types with sensor fusion algorithms to create a complete integrated solution, as each detection method has advantages and disadvantages.

The first step in preventing a drone attack is to install monitoring technology that can detect and distinguish drones from other things like birds and aeroplanes, as well as identify a specific type of drone and inform security officials to deploy countermeasures.
By sending out the radio signals & listening for the echo, a radar system can determine the position and direction of flying objects. Although, traditional systems are not designed to identify small flying objects, and even if they are, they may easily confuse a bird with the smaller drones. A micro-doppler radar, on the other hand, can detect speed changes within the moving objects, making identification simple.
Another option is radio frequency (RF) analyzers, which can detect radio communication between a drone and its controller but are worthless against autonomous drones. To capture photographs of the drone and its payload, security experts have looked at optical cameras with infrared or thermal imaging capabilities.