Abstract: A system is disclosed for avoiding and/or minimizing coupling nulls between an electromagnetic field derived from one or more sources and a plurality of randomly oriented RFID tags. The plurality of tags is arranged to move relative to the filed such that no tag is persistently located in a coupling null relative to the field. The or each tag may be translated and/or rotated relative to the electromagnetic field. Alternatively, the electromagnetic field may be translated and/or rotated relative to the tags. In a further aspect coupling nulls may be avoided by orienting a main axis of the or each source of electromagnetic radiation obliquely relative to a direction of movement of the plurality of tags.

Abstract: A self adjusting RF assembly including an RF radiator is disclosed. The RF assembly includes at least one component that may be replaced by a user of the RF assembly. The RF assembly includes an identification element associated with the at least one component for representing at least one characteristic of the component. The RF assembly includes a monitoring element for monitoring the identification element at least during power up of the RF assembly. The RF assembly also includes an adjusting element for adjusting radiation from the RF radiator wherein the adjusting element is operably associated with the monitoring element to maintain radiation from the RF radiator below a preset limit. The preset limit is typically determined by local electromagnetic compatibility (EMC) regulations. A method for maintaining radiation from an RF assembly below a preset limit is also disclosed.

Abstract: A network is disclosed for matching impedance of an antenna including a first conducting layer to a circuit impedance. The network is adapted to modify at least reactance of the antenna impedance to be substantially equal in magnitude and opposite in sign relative to the circuit impedance. The network includes a first component for modifying the reactance. The first component may form a capacitance in series with the antenna. The network also includes a second component for modifying resistance and the reactance of the antenna impedance. The second component may form a capacitance in parallel with the antenna. The first and second components preferably comprise a second conducting layer adjacent the first layer.

Abstract: A transmission/reception radio-wave aerial for an interrogation device for electronic labels carried by objects, the transmission/reception radio-wave aerial being tuned to an F0 frequency and each electronic label including a radio-wave aerial tuned to the F0 frequency and being associated with an electronic circuit, wherein the transmission/reception radio-wave aerial is arranged to create a magnetic field which modifies the tuning frequency for the radio-wave aerials for the electronic labels in such a way to retune towards the F0 frequency of the aerial of the interrogation device.