Patent ID: 8493180

Claim:
A radio system for spatial sensing applications, comprising: a transmitter operable to send a query message; a transponder comprising at least one antenna, the transponder being operable to send a response message on receipt of the query message; a radio frequency shield moveably interposable between the transmitter and the at least one antenna, the shield being operable to attenuate the signal strength of the query message prior to being received at the at least one antenna; and a receiver operable to receive the response message; wherein the transponder is operable to receive the query message while the shield is interposed between the transmitter and the at least one antenna of the transponder, and wherein the response message sent by the transponder comprises data determined according to the signal strength of the query message received at one or more antennas while the shield is interposed between the transmitter and the at least one antenna of the transponder, the data conveying information indicative of relative spatial positioning of the at least one antenna of the transponder and the radio frequency shield.