The initial ALMA array is composed of 66 high-precision antennas, and operates at wavelengths of 0.32 to 3.6 millimeters (31 to 1000 GHz).
The array has much higher sensitivity and higher resolution than earlier submillimeter telescopes such as the single-dish James Clerk Maxwell Telescope or existing interferometer networks such as the Submillimeter Array or the Institut de Radio Astronomie Millimétrique (IRAM) Plateau de Bure facility.

The antennas can be moved across the desert plateau over distances from 150 m to 16 km, which will give ALMA a powerful variable "zoom", similar in its concept to that employed at the centimetre-wavelength Very Large Array (VLA) site in New Mexico, United States.

The high sensitivity is mainly achieved through the large numbers of antenna dishes that will make up the array.

The telescopes were provided by the European, North American and East Asian partners of ALMA.
The American and European partners each provided twenty-five 12-meter diameter antennas, that compose the main array.
The participating East Asian countries are contributing 16 antennas (four 12-meter diameter and twelve 7-meter diameter antennas) in the form of the Atacama Compact Array (ACA), which is part of the enhanced ALMA.

By using smaller antennas than the main ALMA array, larger fields of view can be imaged at a given frequency using ACA.
 Placing the antennas closer together enables the imaging of sources of larger angular extent.
The ACA works together with the main array in order to enhance the latter's wide-field imaging capability.
The initial ALMA array is composed of 66 high-precision antennas, and operates at wavelengths of 0.32 to 3.6 millimeters (31 to 1000 GHz). The array has much higher sensitivity and higher resolution than earlier submillimeter telescopes such as the single-dish James Clerk Maxwell Telescope or existing interferometer networks such as the Submillimeter Array or the Institut de Radio Astronomie Millimétrique (IRAM) Plateau de Bure facility.
The antennas can be moved across the desert plateau over distances from 150 m to 16 km, which will give ALMA a powerful variable "zoom", similar in its concept to that employed at the centimetre-wavelength Very Large Array (VLA) site in New Mexico, United States.
The high sensitivity is mainly achieved through the large numbers of antenna dishes that will make up the array.
The telescopes were provided by the European, North American and East Asian partners of ALMA. The American and European partners each provided twenty-five 12-meter diameter antennas, that compose the main array. The participating East Asian countries are contributing 16 antennas (four 12-meter diameter and twelve 7-meter diameter antennas) in the form of the Atacama Compact Array (ACA), which is part of the enhanced ALMA.
By using smaller antennas than the main ALMA array, larger fields of view can be imaged at a given frequency using ACA.  Placing the antennas closer together enables the imaging of sources of larger angular extent. The ACA works together with the main array in order to enhance the latter's wide-field imaging capability.
Atacama Large Millimeter Array