Electromagnetically induced torque on a large ring in the microwave range.

We report on the exchange of orbital angular momentum between an electromagnetic wave and a 30 cm diameter ring. Using a turnstile antenna in the GHz range, we induce a torque on a suspended copper strip of the order of 10(-8)  N m. Rotations of a few degrees and accelerations up to 4×10(-4) °/s2 are observed.