ALMA has four types of antennas (three types of 12-m antennas and one type of 7-m antenna), two of which (one 12-m and one 7-m) are developed and manufactured by Japan and the remaining two by Europe and North America.

Four antennas have a slightly different shape because they were designed separately by the three parties making the best use of their expertise to deliver superior performance. Although they are very similar, you can tell them apart easily by the form and position of the quadripod supporting the subreflector.

ALMA antennas developed and manufactured in various countries are sent to Chile and reassembled in the Site Erection Facility (SEF) area at the Operations Support Facility (OSF) at 2900 m asl. After going through rigorous mechanical/performance tests, approved antennas are carried one by one by the transporter to the Array Operations Site (AOS) at 5000 m asl.

The picture shows the four types of antennas during adjustment at the OSF. From right, Japanese 7-m, 12-m (at the back), European 12-m and North American 12-m antennas.
[Photographed by Norikazu Mizuno (NAOJ) ]