Patent ID: 6456228
Filing Date: 2002-09-24
Classification: H01Q

Abstract:
A passive transponder comprising:an antenna having a metal body with main surfaces; a diode connected between the main surfaces of the metal body; wherein the passive transponder, when hit by radio-frequency (RF) power of a first frequency f, retransmits RF power of a second frequency 2f; a first dielectric enclosing the antenna, the first dielectric being adapted to reduce an influence of surroundings of the passive transponder on a near field of the antenna; a transmission line connected to the antenna and to the diode, the transmission line being adapted to match an impedance of the diode to an impedance of the antenna; a second dielectric enclosing the transmission line, the second dielectric being adapted to make the transmission line essentially independent of the surroundings of the passive transponder, wherein the passive transponder has a resonance frequency that is matched to an impedance of the diode, an impedance of the first dielectric, and an impedance of the second dielectric.