frequency (or wavelength): the higher the frequency the higher the resolution.

diameter of the telescope: the bigger the mirror, the higher the resolution.

For a millimeter-wave radio telescope to achieve the same resulution as from a typical optical telescope, the radio telescope must be approximately 1 kilometer in diameter!

Since we cannot make single-dish telescopes that big, we use another trick: break the telescope into pieces and seperate them by a kilometer.

A view of the BIMA site from the end of the north runway looking south. One can see six of the nine working antennas, along with the new control building to the left of the runway.
Signals from the dishes are combined pair-wise, resulting in the raw data. A computer is used to turn the raw data into viewable images.
Creating and processing radio images can be computationally intensive. With larger observing projects, a supercomputer is necessary to process the data in a reasonable amount of time.

Information provided by: http://astro.uchicago.edu