QUASI-OPTICAL VARIABLE BEAMSPLITTER

摘要

A variable beamsplitter (10) for use with quasi-optical millimeter-wave beams. The beamsplitter (10) consists of a circular metal plate (20) into which a periodic array (30) of rectangular slots is cut. The plate (20) is arranged so that the incident millimeter-wave beam is incident at an angle of 45 DEG relative to the surface of the plate (20). The polarization of the incident beam is parallel to the surface of the plate (20). When the orientation of the plate (20) is such that the electric field is perpendicular to the slots (i.e., the electric field is directed across the narrow dimension of the slots), the plate (20) transmits nearly 100% of the incident power. If the plate is rotated about its axis by 90 DEG (while maintaining a 45 DEG angle between the incident beam and the plate) so that the incident electric field is parallel to the slots, then the plate (20) transmits 0% and reflects nearly 100% of the incident power at an angle of 90 DEG relative to the incident beam. By varying the angle of rotation between 0 DEG and 90 DEG , both the reflected and transmitted power can be varied continuously between 0% and 100% of the incident power. The beamsplitter comprises a cooling system for removing heat absorbed from the electromagnetic waves from the edge of the metal plate (20).