1. Solar radio emission is usually characterized only by the intensity, i.e. by a single value at a given frequency.

In polarization measurements the radio emission is characterized by four values (for example, by the unpolarized-component intensity and three components of the polarization ellipse).

Here we see that observations of solar radio emission with a polarimeter give us considerably more extensive information than the usual observations give. It is a very important fact that the polarization of the radio emission is determined by the strength and direction of the magnetic field of emitting regions. Thus, we connect the polarized radio emission with a magnetic field that is noticeably higher than the field in the region which we can study by optical methods.

It should also be noticed that one of the most interesting unsolved problems is establishing the nature of the disturbed solar radio emission. It is clear that new information on the polarization of radio emission will contribute to the solution of this problem; but in spite of its importance and urgency, investigations to solve it are being carried on only in a small number of observatories. The observations in Australia and the work in Japan may be mentioned.