of antennas, is where the antennas should be placed relative to each other, in order to produce the best synthesized images. In 1996 Eric Keto studied this problem for the SMA. He found that the most uniform sampling of spatial frequencies, and thus the cleanest (lowest sidelobe) point spread function was obtained when the antennas were arranged in the shape of a Reuleaux triangle. Because of that study, pads upon which SMA antennas can be placed were arranged to form four Reuleaux trangles, with the easternmost pad forming a shared corner for all four triangles. However the SMA site is a lava field with many rocky ridges and depressions, so the pads could not be placed in exactly the optimal positions. In most cases all eight antennas are deployed on the pads forming one Reuleaux triangle, leading to four configurations named, in order of increasing size, subcompact, compact, extended and very extended. The schedule of antenna moves is determined by the requirements of the approved observing proposals, but tends to follow a roughly quarterly schedule. A custom-built transporter vehicle is used to lift an antenna off of a pad, drive it along one of the dirt access roads, and place it on a new pad while maintaining power to the cooling system for the cryogenic receivers. Each antenna pad has a conduit connecting it to the central building, through which AC power cables, and optical fibers are pulled. Multi-mode optical fibers are used for low bandwidth digital signals, such as ethernet and phone service. Sumitomo LTCD single-mode fiber optic cables are used for the reference signals to generate the LO for the heterodyne receivers and the return of the IF signal from the antenna. The Sumitomo fibers have an extremely low coefficient of thermal expansion, which is nearly zero at the typical temperature below the surface of Mauna Kea. This allows the array to operate without closed-loop delay measurements. Antennas Each of the eight antennas has a 6 meter diameter primary mirror made of 72 machined cast aluminum panels. Machined aluminum was chosen over the lighter carbon fiber alternative, because of concerns that heavy snow accumulation, or windblown volcanic dust, might damage fragile carbon fiber panels. The panels, each about 1 meter wide, were machined to an accuracy of 6 microns. They are supported by a carbon fiber tube backup structure, which is enclosed by aluminum panels to protect it