High-time-resolution swept-frequency microwave polarimeter

The instrument, which was built for the study of solar radiation in the band 2¿4 GHz, is capable of measuring the intensity and state of polarisation of the received energy as a function of time and frequency. Energy is received by a 6ft-diameter, paraboloid reflector with a broad band feed. The receiving system consists of four superheterodyne receivers, from which the desired outputs are generated by crosscorrelation processes. Correlation is performed at the intermediate frequency of 30MHz using a type of diode-ring multiplier. The system has a gain stability of ±2% and adequate incremental sensitivity. The paper discusses the general requirements of a solar polarimeter and describes the design and construction of the instrument. Difficulties caused by r.f. coupling between the receiver inputs are discussed, and some preliminary results are given.