A Swept-Frequency Interferometer for the Study of High-Intensity Solar Radiation at Meter Wavelengths

The paper describes an interferometer which has been constructed for studying the various spectral types of solar activity at meter wavelengths. The instrument is a "swept-frequency" interferometer and is capable of measuring the one-dimensional position and angular size of a transient source on the sun's disk, and of determining the polarization and intensity of the received radiation. All these characteristics are determined as a function of frequency in the range 40-70 mc. Independent position measurements are made at one-second intervals, and source-size measurements at two-second intervals. Polarization measurements are made as an alternative at chosen times. The two antennas of the main interferometer are spaced 1 km apart on an east-west line. The two antennas of the polarization system are erected on a common axis maintained in the direction of the sun. Some preliminary observations have given an indication of the spectrum of source size for activity of spectral Types I and III. In both cases the angular size is found to decrease from about 10 minutes of arc at 45 mc to about 6 minutes of arc at 65 mc.