A system for contactless power and data transmission contains a stationary station and a mobile station. In order to tune a resonant circuit of the mobile station to the resonant frequency of the stationary station, a multiplicity of capacitors which can be connected in parallel with the resonant circuit are provided. An instantaneous operating state of the system is included in the tuning. The realization is easy to integrate.

In one aspect, the present invention provides an air coil 20. The air coil 20 may be made from a strip of electrically conductive material 22 which has an insulating material overlying it. For example, the conductive material may comprise copper. The strip 22 is wound into a coil to perform a plurality of windings. The insulating material electrically insulates each of the winding from adjacent ones of the windings.

A wireless equipment diagnosis system which can perform inspection and maintenance precisely and accurately, and which comprises sensors which measure information on each equipment being diagnosed, a transponder which transmits measured data from the sensors after modulating the measured data; a portable interrogator which acquires the measured data by receiving transmitted signals from the transponder; and a host computer which diagnoses each equipment by implementing predetermined signal processing using information stored in advance and data transferred from the acquired data.

A transponder arrangement is described having an interrogator unit (10) which transmits at least one RF programming sequence and at least one RF interrogation pulse. The responder unit (12) includes a responder unit receiver (130) for receiving data transmitted by the RF programming sequence from the interrogator unit (10). The responder unit (12) then upon receipt of the RF interrogation pulse transmits data, which may have been modified by the programming sequence from the interrogator unit (10), back to the interrogator unit (10) in the form of a modulated RF carrier. The responder unit (12) further comprises a responder unit energy accumulator (136) which stores energy contained in the RF interrogation pulse and a responder unit end of burst detector (142) which upon detection of a decreasing power level of the RF interrogation pulse sends a RF threshold signal. Further contained within the responder unit (12) is a responder unit RF carrier wave generator (130) operating with the frequency contained in the RF interrogation pulse, which is excited upon receipt of a signal from the pluck circuit (196). The responder unit (12) further comprises a responder unit circuitry means (198,200) for providing from the output signal of the RF carrier wave generator a control signal which is utilized to maintain the RF carrier wave and to modulate the RF carrier to be sent back with the stored data.

In one aspect, the present invention provides an air coil 20. The air coil 20 may be made from a strip of electrically conductive material 22 which has an insulating material overlying it. For example, the conductive material may comprise copper. The strip 22 is wound into a coil to perform a plurality of windings. The insulating material electrically insulates each of the windings from adjacent ones of the windings.