RFID system and associated antenna-coupler
A RFID system and an associated antenna-coupler are provided. The system may be for selectively communicating with a targeted transponder from among a group of multiple adjacent transponders is provided. The system may include a transponder conveyance, a transceiver, and an antenna-coupler. The transponder conveyance is adapted to transport at least one targeted transponder from a group of multiple adjacent transponders through a transponder operating region. The transceiver is configured to generate one or more electrical signals. The antenna-coupler has first and second microstrips in a cross-like arrangement relative to each other. Each of the first and second microstrips is configured to transmit one or more electro-magnetic fields concentrated in a near-field region of the antenna-coupler based on the one or more electrical signals for communicating with the targeted transponder.
1. An antenna-coupler for a system having a transceiver and being configured to process one or more smart media and associated transponders of the smart media, the antenna-coupler comprising:
a first microstrip extending a first length from a first end to a first terminating point, wherein the first microstrip is terminated at the first terminating point by a first resistive load and the first microstrip is in communication with the transceiver for receiving and sending one or more electrical signals;
a second microstrip extending a second length from a second end to a second terminating point, wherein the second microstrip is terminated at the second terminating point by a second resistive load and the second microstrip is in communication with the transceiver for receiving and sending one or more additional electrical signals;
wherein the first microstrip and the second microstrip are generally orthogonal to each other forming a cross-like arrangement such that the first length of the first microstrip traverses the second length of the second microstrip;
a ground plane spaced apart from the first and second microstrips; and
at least one substrate extending at least partially between the ground plane and the first and second microstrips.
2. The antenna-coupler according to claim 1 , wherein the first and second microstrips are spaced apart and separated by the at least one substrate.
3. The antenna-coupler according to claim 2 , wherein the first and second microstrips are substantially co-planer and the first microstrip further includes a first section, a second section, and a bridge;
wherein the first section extends from the first end of the first microstrip to approximately the second microstrip, the second section extends from approximately the second microstrip to a second end of the first microstrip, and the first and second sections are linked through the bridge that extends around the second microstrip such that the first and second microstrips do not intersect.
4. The antenna-coupler according to claim 3 , wherein the bridge includes at least a jumper wire.
5. The antenna-coupler according to claim 3 , further comprising an input port for connecting both the first microstrip and the second microstrip to the transceiver.
6. The antenna-coupler according to claim 1 , further comprising:
a first input port for connecting the first microstrip to the transceiver; and
a second input port for connecting the second microstrip to the transceiver.
7. The antenna-coupler according to claim 1 , wherein each of the first and second microstrips define a characteristic impedance and wherein the first resistive load is greater than the characteristic impedance of the first microstrip and the second resistive load is greater than the characteristic impedance of the second microstrip.
8. The antenna-coupler according to claim 7 , wherein each of the first and second lengths is substantially equal to a multiple of one half a wavelength of an operational frequency of the antenna-coupler.
9. The antenna-coupler according to claim 8 , wherein each of the first and second microstrips has a tapered profile.