Air Defense: Ray Guns Versus Small Threats


July 17, 2019: The U.S. Air Force is testing two AUD (Anti UAV Defense) systems that use strong microwave electronic transmissions to disrupt the electronics in UAVs (Unmanned Aerial Vehicles) and cause them to crash. The air force has tested two such weapons which differ mainly in terms of range and price. The system closest to combat zone use is THOR (Tactical High Power Microwave Operational Responder), which is a $10 million system that is shipped in and used from a standard 40 foot shipping container. The container can be hauled around on a flatbed truck or placed on the ground. Inside the container is a microwave transmitter that looks like a large satellite dish mounted on a base that can quickly rotate the dish to face the threat and transmit a short burst of microwave energy. Range of THOR has not been revealed but based on work already done on “directed energy” systems and the fact that THOR is powered by a generator that is also in the shipping container, the effective range is probably not more than a few hundred meters. The microwave energy is sufficient to damage the electronics on commercial UAVs used by Islamic terrorists to carry “swarm attacks” on military bases in Syria. Such attacks have frequently been used against a Russian airbase in western Syria, near the Mediterranean coast. The U.S. Air Force fears its bases, especially temporary or permanent ones overseas, could be subject to similar attacks by commercial UAVs carrying small payloads of explosives and using GPS to guide the UAVs to a base where the explosives detonate and cause damage. Such attacks have been used successfully in Yemen by Shia rebels and in one case attacked a large military ceremony and caused a lot of casualties.

The air force also has a longer-range system called CHIMERA (Counter-Electronic High-Power Microwave Extended-Range Air Base Air Defense) that won’t be ready for realistic testing until 2020. THOR has already downed groups of UAVs in tests and the air force wants to buy many systems for base defense in areas threatened by swarm attacks.

The microwave energy systems used by THOR and CHIMERA are similar to the EMP (Electromagnetic Pulse) weapons developed since the 1990s to destroy electronics in general. Since the 1950s it was known that the powerful EMP put out by nuclear weapon detonations could damage or destroy solid-state (transistors and microelectronics) devices over a wide area. Since the 1990s, devices using high-powered microwave (HPM) devices have been developed to create focused EMP on demand without all the nuclear blast and radioactivity. The most commonly mentioned device to generate HPM is the AESA (Active Electronically Scanned Array) radars that are becoming standard equipment in modern warplanes. AESA is more reliable and, increasingly, no more expensive than the older mechanical (a small dish that moves around inside a dome) radar. AESA is also easier and cheaper to maintain, which makes a more expensive AESA cheaper, over its lifetime, than a cheaper (to buy) mechanically scanned radar. More and more nations (including China and Russia) are manufacturing AESA radars and equipping their ships and aircraft with this stuff. All these nations are also manufacturing or developing EMP “bombs” that could be used to sabotage military bases or civilian facilities. For a long time, EMP was believed to be an unlikely threat because you needed a nuclear war to create EMP. Naturally, the blast and radiation damage from the nukes was seen as more of a threat than EMP. But now that has changed.

There are other, cheaper and battle-tested AUD systems that will also deal with multiple UAV attacks. The Israeli Drone Dome systems cost $3.4 million each and consist of a 360 degree radar system, an electro-optical day/night surveillance unit and a wideband (most frequencies drones use) detector. With all this Drone Dome can reliably detect any small quadcopter or fixed-wing UAV within 3,500 meters. Most quadcopters and UAVs encountered are larger and these can be detected out to ten kilometers. Once spotted Drone Dome can use a focused jamming signal that will disrupt any radio control signals and force the drone to crash or operate erratically. Drone Dome has an optional laser gun that can be aimed by Drone Dome to destroy the drone at ranges up to 2,000 meters. In a combat zone, you can also employ machine-guns or snipers to bring down the drone. The same Israeli firm (Rafael) that developed the Iron Dome system (for effectively and economically destroying rockets and shells from mortar and artillery) in 2005 had, by 2017, developed a version optimized to detect and shoot down small UAVs. Drone Dome is a lot cheaper because it does not use $90,000 Tamir guided missiles to intercept rockets or shells headed for residential areas or military targets. Drone Dome uses a radar that can detect most small UAVs at ranges of up to 30 kilometers at altitudes of 10 meters (30 feet) to 10,000 meters. Drone Dome is not a radical development but part of a trend. Since 2010 Israeli firms have developed a growing number of AUD systems largely because Israel is a nation that is most often threatened by hostile use of UAVs, particularly small commercial ones increasingly used by Islamic terrorists and criminal gangs.

What makes Drone Dome different is its heavy use of electronic sensors to detect and jam the control signals used by UAVs, leaving the laser as a last resort. Several AUD systems are already in service and effective because they are good at detecting UAVs electronically and either jamming those control signals or taking over the control signals and capturing (by making it land) the UAV. Troops in Iraq and Syria were asking for AUD systems that used lasers and better UAV detection systems as well those with jammers to disable UAVs. There is a need for AUDs that can detect and destroy UAVs that do not use control signals and basically go on pre-programmed missions guided by GPS. This can be to take photos or deliver a small explosive. Usually, it is to take photos and return. Drone Dome is one of several AUD systems equipped to detect and locate UAVs operating in pre-programmed mode and destroy or disable them quietly with a vehicle-mounted laser.

AUDs similar to Drone Dome also use one or more radar systems and one or more sensor systems for detecting UAV control signals or visual images (that pattern recognition software can quickly identify what it is). While commercial UAVs are more common the basic design principles have not changed. AUDs are constantly evolving to better detect and disable or destroy unwanted UAVs. The best ones are recent models that tend to be very expensive and used only for extreme situations, like UAV defense in combat zones.

Airports, especially the large ones, will be driven by legal liability concerns to join the military is buying the latest AUDs, which at least lowers the AUD price and inspires even faster innovation and development. Commercial airports are increasingly having flight operations disrupted by the presence of commercial UAVs (usually cheap quadcopters). These UAVs are not terrorist weapons but used by someone making videos and unaware (or not caring) of the illegality of using a UAV close to an airport. AUDs for these situations must meet certain reliability, range and effectiveness goals in order to sell profitably. That is where military users will find another source for effective base defense systems.




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