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 ring resonator, operating in a TM mode, show that substantial levitation forces are available at millimetre-wave frequencies, and that the system is intrinsically stable