Broad bandwidth, high impedance transponder for electronic identification system

摘要

A transponder 14.1 for an electronic radio frequency identification system comprises an antenna 18 having an antenna impedance at a feedpoint thereof, The transponder further comprises an electronic circuit 19 having an input connected to the antenna. The antenna impedance having impedance characteristics for developing first and second voltage maxima (36,38) across the input at first and second frequencies (fL and fH) respectively, thereby to provide a continuous operative frequency band for the transponder including the first and second frequencies.