(interferometry to simulate a larger aperture telescope)
Aperture synthesis (synthesis imaging)
is a method of using an interferometer incorporating
an array of telescopes,
to produce an image with the angular resolution
like that provided by a single aperture
as wide as the array's baseline length.
The method is used in optical,
infrared, microwave, and radio astronomy.
The term synthetic aperture telescope (SAT) refers
to a telescope-array set up to do this,
the term most often used when the telescopes are optical.
Any interferometer array of two ore more telescopes (e.g., multiple
radio-telescope dishes) is intended to produce the high angular
resolution associated with their baselines, and it would
seem the term aperture synthesis applies to any of them.
But I suspect the term is often meant specifically to indicate
post-calculations that generate an image.
Phase data can be used in such calculations, and sometimes it is
said that aperture syntheses requires it.
However, I've seen reference to aperture syntheses without phase
data and I presume methods of image-production without phase data
exist but are inferior.