The U.S. Defense Department has revealed high-powered microwave (HPM) systems for air defense applications to shoot down everything from shoulder-launched surface-to-air (SAM) missiles (like the U.S. Stinger and Russian-made SA-7/16/18) to inbound cruise missiles. Ground-based and airborne systems would be built around Active Electronically Scanned Array (AESA) radar technology, using the ability of the radar to focus a concentrated beam of radio energy onto a missile and scramble its electronic seeker.
The Air Force is outlining the capability of an advanced radar onboard the proposed E-10 a follow-on to the E-8 JointStars aircraft to find and track stealthy cruise missile targets at ranges up to 370 kilometers and be able to "scramble" onboard electronics with a burst of energy at ranges of up to 180 kilometers. At ranges of 18 kilometers, it has the capability to destroy those electronics. Since everything from targeting sensors to engine control on a modern cruise missile requires computer control, the radar would give the Air Force a long-range "soft kill" capability against such threats. The E-10 radar is 1.2 meters tall by 6 meters long and would be flown on a wide-boded aircraft such as the Boeing 767.
Interesting, the same airborne AESA technology can be found in a smaller form on the Global Hawk UAV, some models of F-15 and F/A-18 fighters, and on the F/A-22 and F-35 fighters. In theory, smaller radars most likely the F/A-22 have a shorter range capability to scramble and destroy missile electronics of any sort, either cruise missiles and/or higher-performance air-to-air missiles. While some types of cruise missiles around the world designed in part to deliver nuclear weapons incorporate shielded electronics against EMP that may provide some protection, air-to-air missiles would be highly vulnerable to HPM attack.
On the ground, Raytheon has prototyped a HPM designed to kill shoulder launched SAMs and is proposing to build a variant called Vigilant Eagle to protect civilian aircraft against SAM attacks. The system would combine a ring of infrared sensors around the area to be protected, a command center, and two billboard-size radar emitters. The company intends to build a full-site version using their own money within two years for a full-scale demonstration at an airport.
Vigilant Eagle would cost around $25 million per airport, so if the U.S.'s 31 biggest airports were protected the cost would be less than a billion cheap, compared to the $6-12 billion it might cost to put SAM countermeasures on 6,000 U.S. commercial aircraft. The system could also be packaged in a mobile configuration for use against anything that had an electronics package, ranging from sophisticated cruise missiles to smart bombs and even rocket and artillery fuzes.
Most of the recent hype in HPM weapons has focused around one-shot devices carried by cruise missiles to offensively attack SAM site electronics or a multi-shot weapon that could be carried by UAVs and manned aircraft. The challenge has been making a system powerful and compact enough to put on flying vehicle, a problem that is less of an issue with a ground-based installation.