The Synthesis of Large Radio Telescopes

TLDR

Conventional radio astronomy is limited by the resolving power achievable with standard aerial construction. The method synthesizes a large equivalent aerial by moving two antennas across the area of a larger aperture and mathematically combining the data, allowing phase‑shifted scans over a wide solid angle without extra observing time. An interferometric system for radio stars was built with an equivalent resolving area of 8.10^5 sq ft and a pencil‑beam system with 3.10^6 sq ft, both achieving a collecting area of about 2.10^5 sq ft.

Abstract

Many investigations in radio astronomy are limited by the resolving power which can be achieved by conventional methods of aerial construction. A new method of obtaining increased resolving power has been developed, which has been applied to the construction of both “pencil-beam” systems and interferometers. In this method two aerials are arranged so that their relative position may be altered to occupy successively the whole area of a much larger equivalent aerial. By combining mathematically the information derived from these different positions, it is possible to obtain a resolving power equal to that of the large equivalent aerial. Since the combination of the individual records may be done with different phase relationships, it is possible, without extra observations, to “scan” the synthesized aerial over an appreciable solid angle; because of this the total observing time of a synthesized instrument is of the same order as that of a conventional instrument. An interferometric system designed for the study of radio stars has been built which has an equivalent area for resolution of 8.10 5 sq. ft as well as a “pencil-beam” system with an equivalent area of 3.10 6 sq.ft. The sensitivity of both systems corresponds to a “collecting area” of about 2.10 5 sq. ft.