Rotation and dichroism associated with microwave propagation in chiral composite samples

In this paper we present experimental results on the angle of rotation and the axial ratio (dichroism) associated with the propagation of microwave waves in chiral composite samples (a phenomenon akin to optical rotation and optical dichroism). In our experiments the chiral composite samples tested were made in the form of planar slabs and consisted of low loss dielectric matrix materials in which miniature copper springs of left only, right only, or an equal mixture of left and right handedness were randomly distributed and oriented. The normally incident wave was linearly polarized. In the chiral sample the linearly polarized wave decomposes into left and right circularly polarized waves which propagate with different speeds and different attenuations leading to an elliptically polarized transmitted wave whose orientation ( electromagnetic rotation ) and axial ratio ( dichroism ) are proportional to the concentration of springs. Rotation and dichroism are shown to be zero in the equichiral samples.