Rainfall estimated using radar relies heavily on the knowledge of the microstructure of rain. Because little is known about this, it is a challenge to use radar for applications where quantitative rainfall data of high accuracy is needed. There are two ways to solve this problem. One is to make the radar rainfall estimation less dependent on the knowledge of the microstructure of the rain. The other way is to gain a better understanding of this microstructure. The first solution can be implemented when using radar that has a sufficiently small measurement volume, and the second solution can be implemented in radars that have larger measurement volumes. Results from experimental work carried out using the high-resolution (~3 m) TARA (Transportable Atmospheric Research Radar) radar at Cabauw, The Netherlands and computer simulations are used to analyze the information that can be obtained about the microstructure of rain and the rainfall rate from the raw radar data.