The basic theory of radio broadcasting is discussed from an experimental point of view. First, concepts like wave modulation and tuning are explained with the use of instruments in the physics laboratory. Then, a very basic radio receiver is described and assembled, whose most important feature, like in the old "crystal radios", is the absence of a power supply. Even if the underlying general concepts are usually described in general physics classes at high school and university, for students this setup is a practical example of the application of electromagnetic waves. (Contains 8 figures and 12 footnotes.)