Abstract: This invention relates to a method for detecting chipless radio frequency identification devices (RFID), in particular chip detection, also referred to as chipless RFID tags. This invention also relates to the devices and tags which may be used in the claimed method.

Abstract: The present invention relates to a set of security documents. Each security document within the set having an optical code, notably a barcode, which is neither connected nor coupled to any electronic chip that may be carried by the security document. The optical code on each security document within the set encodes the same information for the same optical reader. Each security document having different respective electromagnetic signature, these signatures being unique to each of the security documents.

Abstract: The present invention relates to a set of security documents. Each security document within the set having an optical code, notably a barcode, which is neither connected nor coupled to any electronic chip that may be carried by the security document. The optical code on each security document within the set encodes the same information for the same optical reader. Each security document having different respective electromagnetic signature, these signatures being unique to each of the security documents.

Abstract: A chipless RFID tag comprises a plurality of disjoint parallel conducting bands formed on a dielectric support, in which conducting bridges interlink neighboring conducting bands, the conducting bridges delimiting, between the conducting bands, portions of dielectric bands of distinct lengths, each portion of dielectric brand determining a resonant frequency of the tag, the set of resonant frequencies of the tag defining an identification code.

Abstract: A chipless RFID tag comprises a plurality of disjoint parallel conducting bands formed on a dielectric support, in which conducting bridges interlink neighboring conducting bands, the conducting bridges delimiting, between the conducting bands, portions of dielectric bands of distinct lengths, each portion of dielectric brand determining a resonant frequency of the tag, the set of resonant frequencies of the tag defining an identification code.

Abstract: The present invention relates to compositions comprising(a) at least one polyimide having an inherent viscosity of at least 0.1 dl/g (measured at 25.degree. C. on a 0.5% by weight solution in N-methylpyrrolidone) and containing at least 50 mol % of structural units of the formula I ##STR1## in which m and p independently of one another are integers from 0 to 4, n is an integer from 0 to 3, R.sup.1 and R.sup.2 independently of one another are C.sub.1 -C.sub.6 -alkyl or C.sub.1 -C.sub.6 -alkoxy and R.sup.3 is a divalent radical of an aromatic diamine which is substituted in at least one ortho-position relative to at least one N atom by alkyl, alkoxy, alkoxyalkyl, cycloalkyl or aralkyl or in which two adjacent C atoms of the aromatic radical are substituted by alkylene, and(b) at least one aromatic polyimide which is soluble in organic solvents and photocrosslinkable and which contains at least 50 mol %, relative to the total quantity of diamine units, of radicals R.sup.