High Frequency Active Auroral Research Program
origional source wikipedia, but edited by me to make it to the point:


The High Frequency Active Auroral Research Program (HAARP) is an ionospheric research program jointly funded by the US Air Force, the US Navy, the University of Alaska and the Defense Advanced Research Projects Agency (DARPA). Its purpose is to analyze the ionosphere and investigate the potential for developing ionospheric enhancement technology for radio communications and surveillance purposes. The HAARP program operates a major Arctic facility, known as 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 and an induction magnetometer, are used to study the physical processes that occur in the excited region.

Work on the HAARP Station began in 1993. The current working IRI was completed in 2007, and its prime contractor was BAE Advanced Technologies.

As of 2008, HAARP had incurred around $250 million in tax-funded construction and operating costs. HAARP has also been blamed by conspiracy theorists for a range of events, including numerous natural disasters.
The HAARP project aims to direct a 3.6 MW signal, in the 2.8–10 MHz region of the HF [High Frequency] band, into the ionosphere. The signal may be pulsed or continuous. Then, effects of the transmission and any recovery period can be examined using associated instrumentation, including VHF and UHF radars, HF receivers, and optical cameras. According to the HAARP team, this will advance the study of basic natural processes that occur in the ionosphere under the natural but much stronger influence of solar interaction, as well as how the natural ionosphere affects radio signals.

This will enable scientists to develop techniques to mitigate these effects in order to improve the reliability and/or performance of communication and navigation systems, which would have a wide range of applications in both the civilian and military sectors, such as an increased accuracy of GPS navigation, and advancements in underwater and underground research and applications. This may lead to improved methods for submarine communication and the ability to remotely sense the mineral content of the terrestrial subsurface, among other things. One application would be to map out the underground complexes of countries. The current facility lacks the range to reach these countries, but the research could be used to develop a mobile platform.

The HAARP program began in 1990. The project is funded by the Office of Naval Research and jointly managed by the ONR and Air Force Research Laboratory, with the principal involvement of the University of Alaska. Many other universities and educational institutions have been involved in the development of the project and its instruments, namely the University of Alaska (Fairbanks), Stanford University, Penn State University (ARL), Boston College, UCLA, Clemson University, Dartmouth College, Cornell University, Johns Hopkins University, University of Maryland, College Park, University of Massachusetts, MIT, Polytechnic Institute of New York University, and the University of Tulsa. The project's specifications were developed by the universities, which are continuing to play a major role in the design of future research efforts.

According to HAARP's management, the project strives for openness and all activities are logged and publicly available. Scientists without security clearances, even foreign nationals, are routinely allowed on site. The HAARP facility regularly (once a year on most years according to the HAARP home page) hosts open houses, during which time any civilian may tour the entire facility. In addition, scientific results obtained with HAARP are routinely published in major research journals (such as Geophysical Research Letters, or Journal of Geophysical Research), written both by university scientists (American and foreign) or by US Department of Defense research lab scientists. Each summer, the HAARP holds a summer-school for visiting students, including foreign nationals, giving them an opportunity to do research with one of the world's foremost research instruments.
HAARP's main goal is basic science research of the uppermost portion of the atmosphere, known as the ionosphere. Essentially a transition between the atmosphere and the magnetosphere, the ionosphere is where the atmosphere is thin enough that the sun's x-rays and UV rays can reach it, but thick enough that there are still enough molecules present to absorb those rays. Consequently, the ionosphere consists of a rapid increase in density of free electrons, beginning at ~70 km, reaching a peak at ~300 km, and then falling off again as the atmosphere disappears entirely by ~1000 km. Various aspects of HAARP can study all of the main layers of the ionosphere.

The profile of the ionosphere, however, is highly variable, showing minute-to-minute changes, daily changes, seasonal changes, and year-to-year changes. This becomes particularly complicated near the Earth's poles, where a host of physical processes (like auroral lights) are unlocked by the fact that the alignment of the Earth's magnetic field is nearly vertical.

On the other hand, the ionosphere is traditionally very difficult to measure. Balloons cannot reach it because the air is too thin, but satellites cannot orbit there because the air is still too thick. Hence, most experiments on the ionosphere give only small pieces of information. HAARP approaches the study of the ionosphere by following in the footsteps of an ionospheric heater called EISCAT near Tromsø, Norway. There, scientists pioneered exploration of the ionosphere by perturbing it with radio waves in the 2–10 MHz range, and studying how the ionosphere reacts. HAARP performs the same functions but with more power, and a more flexible and agile HF beam.
The main instrument at HAARP Station is the Ionospheric Research Instrument (IRI). This is a high power, high-frequency phased array radio transmitter with a set of 180 antennas, disposed in an array of 12x15 units that occupy a rectangle of about 33 acres (13 hectares). The IRI is used to temporarily energize a small portion of the ionosphere. The study of these disturbed volumes yields important information for understanding natural ionospheric processes.

During active ionospheric research, the signal generated by the transmitter system is delivered to the antenna array and transmitted in an upward direction. At an altitude between 70 km (43 mi) to 350 km (217 mi) (depending on operating frequency), the signal is partially absorbed in a small volume several tens of kilometers in diameter and a few meters thick over the IRI. The intensity of the HF signal in the ionosphere is less than 3 µW/cm², tens of thousands of times less than the Sun's natural electromagnetic radiation reaching the earth and hundreds of times less than even the normal random variations in intensity of the Sun's natural ultraviolet (UV) energy which creates the ionosphere. The small effects that are produced, however, can be observed with the sensitive scientific instruments installed at the HAARP Station, and these observations can provide information about the dynamics of plasmas and insight into the processes of solar-terrestrial interactions.

Each antenna element consists of a crossed dipole that can be polarized for linear, ordinary mode (O-mode), or extraordinary mode (X-mode) transmission and reception.[8][9] Each part of the two section crossed dipoles are individually fed from a custom built transmitter, that has been specially designed with very low distortion. The Effective Radiated Power (ERP) of the IRI is limited by more than a factor of 10 at its lower operating frequencies. Much of this is due to higher antenna losses and a less efficient antenna pattern.

The IRI can transmit between 2.7 and 10 MHz, a frequency range that lies above the AM radio broadcast band and well below Citizens' Band frequency allocations. The HAARP Station is licensed to transmit only in certain segments of this frequency range, however. When the IRI is transmitting, the bandwidth of the transmitted signal is 100 kHz or less. The IRI can transmit in continuous waves (CW) or in pulses as short as 10 microseconds (µs). CW transmission is generally used for ionospheric modification, while transmission in short pulses frequently repeated is used as a radar system. Researchers can run experiments that use both modes of transmission, first modifying the ionosphere for a predetermined amount of time, then measuring the decay of modification effects with pulsed transmissions.