The High Frequency Active Auroral Research Program (HAARP) is an ionospheric research program jointly funded by the U.S. Air Force, the U.S. Navy, the University of Alaska[clarification needed], and the Defense Advanced Research Projects Agency (DARPA). Designed and built by BAE Advanced Technologies (BAEAT), its purpose is to analyze the ionosphere and investigate the potential for developing ionospheric enhancement technology for radio communications and surveillance. The HAARP program operates a major sub-arctic facility, named the HAARP Research Station, on an Air Force-owned site near Gakona, Alaska.
The most prominent instrument at the HAARP Station is the Ionospheric Research Instrument (IRI), a high-power radio frequency transmitter facility operating in the high frequency (HF) band. The IRI is used to temporarily excite a limited area of the ionosphere. Other instruments, such as a VHF and a UHF radar, a fluxgate magnetometer, a digisonde (an ionospheric sounding device), and an induction magnetometer, are used to study the physical processes that occur in the excited region.