A method for compensating for the Doppler effect in a communication system where messages are transmitted at a low data rate to a user terminal that is inside a building. The invention further relates to methods employing such compositions, and methods of making these compositions. The rotor has axially aligned rotation shafts respectively and rotatably received in holes defined in the casing for rotatably supporting the rotor inside the casing. Two of these projections have an interspacing of at least half the length of the member.