Patent attributes
A rotary signal coupler for providing signal coupling to a Surface Acoustic Wave (SAW) device (4) mounted on a shaft (5) includes a first electrically conducting loop (21) mounted on a disc (23) and connected to the SAW device (4), and a second electrically conductive loop (22) mounted on a disc (24) and connected to external electronic circuitry. The disc (23) is fixed relative to the shaft (5) and the disc (24) is fixed relative to the structure in which the shaft (5) rotates so that the loops (21, 22) are inductively coupled. A grounded screen (27), which preferably takes the form of a plurality of radially extending fingers is located on the disc (23) and positioned between the loops (21, 22) to eliminate capacitive coupling therebetween.
