[1][2] The array is situated at the Hat Creek Radio Observatory in Shasta County, 290 miles (470 km) northeast of San Francisco, California.

The project was originally developed as a joint effort between the SETI Institute and the Radio Astronomy Laboratory (RAL) at the University of California, Berkeley (UC Berkeley), with funds obtained from an initial US$12.5 million donation by the Paul G. Allen Family Foundation and Nathan Myhrvold.

In August 2014, the installation was threatened by a forest fire in the area and was briefly forced to shut down, but ultimately emerged largely unscathed.

In March 2004, following the successful completion of a three-year research and development phase, the SETI Institute unveiled a three-tier construction plan for the telescope.

The ATA has four primary technical capabilities that make it well suited for a range of scientific investigations: a very wide field of view (2.45° at λ = 21 cm, the wavelength of the hydrogen line), complete instantaneous frequency coverage from 0.5 to 11.2 gigahertz (GHz), multiple simultaneous backends, and active interference mitigation.

The instantaneous frequency coverage of more than four octaves is unprecedented in radio astronomy, and is the result of a unique feed, input amplifier and signal path design.

All-sky surveys are an important part of the science program,[clarification needed] and the ATA will have increased efficiency through its ability to conduct extraterrestrial intelligence searches (SETI) and other radio astronomy observations simultaneously.

Simultaneous observations are possible because for SETI, wherever the telescope is pointed, several target stars will lie within the large field of view afforded by the 6 m dishes.

The ATA is planned to comprise 350 6 m dishes and will make possible large, deep radio surveys that were not previously feasible.

The telescope design incorporates many new features, including hydroformed antenna surfaces, a log-periodic feed covering the entire range of frequencies from 500 megahertz (MHz) to 11.2 GHz, and low-noise, wide-band amplifiers with a flat response over the entire band, thus making it possible to amplify the sky signal directly.

This amplified signal, containing the entire received bandwidth, is brought from each antenna to the processing room via optical fiber cables.

This means that as electronics improve and wider bandwidths are obtainable, only the central processor needs to change, and not the antennas or feeds.

The panel for the Astronomy and Astrophysics Decadal Survey in its fifth report, Astronomy and Astrophysics in the New Millennium (2001), endorsed SETI and recognized the ATA (then called the 1-Hectare Telescope) as an important stepping stone towards the building of the Square Kilometer Array telescope (SKA).

Although cost estimates of unbuilt projects are always dubious, and the specifications are not identical (conventional telescopes have lower noise temperature, but the ATA has a larger field of view, for example), the ATA has potential promise as a much cheaper radio telescope technology for a given effective aperture.

For example, the amount spent on the first ATA-42 phase, including technology development, is roughly one third of the cost of a new copy of a Deep Space Network 34 m antenna of similar collecting area.

[4] This is about two times cheaper than the $85 million cost of the last large radio astronomy antenna built in the US, the Green Bank Telescope, of similar collecting area.

[15] The ATA aspires to be among the world's largest and fastest observing instruments, and to permit astronomers to search many different target stars simultaneously.

Since its inception, the ATA has been a development tool[clarification needed] for astronomical interferometer technology (specifically, for the Square Kilometer Array).

[4] Funding for building additional antennas is currently being sought by the SETI Institute from various sources, including the United States Navy, Defense Advanced Research Projects Agency (DARPA), National Science Foundation (NSF) and private donors.

[18][19][20][21] Three phased array beamformers[22] utilizing the Berkeley Emulation Engine 2 (BEE2) were deployed in June 2007 and have been integrated into the system to allow for simultaneous astronomical and SETI observations.

[30] In 2012, the ATA was funded by a $3.6 million philanthropic donation by Franklin Antonio, cofounder and Chief Scientist of Qualcomm Incorporated.

[32][needs update] In November 2015, the ATA studied the anomalous star KIC 8462852,[33][34] and in autumn 2017 the Allen Telescope Array examined the interstellar asteroid 'Oumuamua for signs of technology, but detected no unusual radio emissions.

For example, the Allen Telescope Array has offered to provide the mooncast data downlink for any contestants in the Google Lunar X Prize.

Following this suggestion, Andrew Siemion and an international team of astronomers and engineers developed an instrument called "Fly's Eye" that allowed the ATA to search for bright radio transients, and observations were carried out between February and April 2008.

The time required for mapping a large area to a given sensitivity is proportional to (ND)2, where N is the number of elements and D is the diameter of the dish.

For point source surveys, the ATA-42 is comparable in speed to Arecibo and the Green Bank Telescope (GBT), but three times slower than the Very Large Array (VLA).

The unique interior frame rim-supported compact mount allows excellent performance at low cost.

Each Programmable Detection Module (one of 28 PCs) can analyze 2 MHz of dual-polarization input data to generate spectra with spectral resolution of 0.7 Hz and time samples of 1.4 seconds.