| 摘要 |
The invention relates to a card-like information carrier readable with RF waves and having resonant devices at spaced intervals across its face that are tuned to different resonant frequencies, an item of information being encoded in the pattern of those frequencies. Each device comprises a dielectric sheet having a deposit of conductive material overlying each of its surfaces. At least one deposit has a spiral slit that defines in it a spiral inductance coil. Each deposit has a capacitance region opposing a like capacitance region of the other and having substantial extension in directions along and away from the slit. Each device can be returned to a predetermined higher resonant frequency by punching through the carrier to reduce areas of opposing capacitance regions of the device, or it can be made non-resonant by punching through all turns of its coil.
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