Magnetic suspension for micro-actuators using microwave cavity resonators

A new levitation technique which harnesses the Lorentz forces acting on the walls of a metallic electromagnetic cavity resonator is described. Both disc-shaped or cylindrical 'floats' which form part of the wall of the cavity are described. If the frequency of operation is high enough (> 100 GHz) the dimensions of the system will be in the millimetre range. The technique requires that the cavity mode employed is relatively independent of the movement of the 'floating' wall. This basically means that the cavity wall currents must flow parallel to the edges of the floating wall, and that the wall is lifted from its contacting position by a distance of more than about 1% of the RF wavelength at the operating frequency. Experiments using a high-Q ting resonator, operating in a TM mode, show that substantial levitation forces are available at millimetre-wave frequencies, and that the system is intrinsically stable.