Abstract: A transponder system employs a transponder antenna with a distributed inductance and capacitance that exhibit parallel and series resonant frequencies. Transmissions to the transponder circuit are made at one or more parallel resonant frequencies to maximize the excitation of the transponder circuit, while return signals transmitted back from the transponder are modulated at one or more series resonant frequencies to maximize the signal current. The transponder antenna is implemented as a pair of aligned coils on opposite sides of a thin dielectric substrate, with the coils connected together through the substrate at one point and the substrate thickness not more than about 25 microns to obtain a significant mutual inductance between the coils.

Abstract: A transponder is formed of a very thin flexible substrate (10) on opposite sides of which are formed first (26) and second (31) series connected halves of a single antenna coil having ends connected to an integrated circuit die (50) mounted to a corner of the substrate. A plurality of bond pads (12a-12e) and programming pads (14a-14e) are also formed on the substrate and operatively connected to couple the antenna coils and the programming pads through the bond pads to the integrated circuit die. Unique configurations and arrangements of a die mounting site (46), bond pads (12a-12e), program pads (14a-14e), and vias (22,24) through the substrate enable an inexpensive simple construction. Protective laminates (58,60) on either side of the substrate are bonded to one another around the edges that circumscribe the substrate and also are bonded to one another at interior portions through a slot (20) formed in the substrate.

Abstract: An RF transponder couples the outer end of a coiled antenna winding to a transponder circuit located inside the winding by a lead line that crosses over the winding turns and is separated from the winding by a dielectric material. The width of the lead line is substantially greater than the antenna line width, yielding capacitances at the cross-over sites that establish a resonant frequency for communicating with the transponder circuit at a predetermined RF frequency. An optional discrete capacitor can also be used to boost the capacitance to a desired level. All of the transponder components are formed on one side of a flexible substrate, the opposite side of which is coated with an adhesive that is covered by a peel-off sheet, allowing the transponder to be affixed to packages as part of a package identification system.

Abstract: RF communication through an RF barrier is facilitated by an RF field concentrating core that is lodged within an opening through the barrier and extends out from at least one side of the barrier. An antenna coil is wound around the core, with a capacitor connected across the coil to establish a parallel resonant circuit at the exciting frequency. The core/coil combination provides a bidirectional RF coupler for transmitting signals between opposite sides of the barrier. It is particularly useful for transponder systems in which a transponder is located within an RF-blocking enclosure, and is interrogated by an exciter/reader outside the enclosure.