A Mathematical Model of a Rotational Frequency Translation Device

摘要

An analysis was made which provides a theoretical explanation of a unique radiation torque experiment performed by Allen, in which circularly polarized (cp) microwave power was used to impart continuous rotary motion to an object supported within a circular waveguide. Under the action of the cp wave, an oscillating current was set up in a rod dipole resulting in an oscillating dipole moment. Part of the energy scattered by the rotating dipole is frequency shifted. Torques arise from the interactions between the E-field of the wave and the induced dipole moment, and between the oscillating current in the dipole and the longitudinal H-field in the waveguide. The magnitudes of these torques were derived for two cases of interest; the open waveguide and the shorted waveguide. The magnitudes of the spectral components of the radiation scattered by the dipole were also derived along with their characteristic polarizations. A cursory analysis shows that photons are conserved in such an experiment. (Author)