Frequency multiplexed radio frequency identification

• US 10,121,030 B1
• Filed: 06/28/2017
• Issued: 11/06/2018
• Est. Priority Date: 06/29/2016
• Status: Active Grant

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Fink, Patrick W., Lin, Gregory Y., Kennedy, Timothy F., Ngo, Phong H., Kinion, Lucas S.
• Primary Examiner(s): Blouin, Mark
• Application Number:
  US15/635,704
• Time in Patent Office: 496 Days
• Field of Search: 340 101
• CPC Class Codes: G06K 19/0724 the arrangement being a circuit for communicating at a plurality of frequencies, e.g. for managing time multiplexed communication over at least two antennas of different types
• CPC Class Codes: G06K 19/0726 the arrangement including a circuit for tuning the resonance frequency of an antenna on the record carrier
• CPC Class Codes: G06K 19/07767 the first and second communication means being two different antennas types, e.g. dipole and coil type, or two antennas of the same kind but operating at different frequencies
• CPC Class Codes: G06K 7/10069 the collision being resolved in the frequency domain, e.g. by hopping from one frequency to the other frequency hopping or spread spectrum techniques H04B7/00
• CPC Class Codes: G06K 7/10356 using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas
• CPC Class Codes: H01Q 1/2208 associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems methods or arrangements for sensing record carriers, e.g. for reading patterns G06K7/00; record carrier for use with machines and with at least a part designed to carry digital markings G06K19/00
• CPC Class Codes: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H01Q 15/0013 said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective
• CPC Class Codes: H01Q 15/242 Polarisation converters
• CPC Class Codes: H01Q 21/0075 Stripline fed arrays H01Q21/065 takes precedence
• CPC Class Codes: H01Q 21/08 the units being spaced along or adjacent to a rectilinear path waveguide fed H01Q21/0037
• CPC Class Codes: H01Q 21/205 providing an omnidirectional coverage turnstile aerials H01Q21/26
• CPC Class Codes: H01Q 3/22 varying the orientation in accordance with variation of frequency of radiated wave
• CPC Class Codes: H01Q 3/40 with phasing matrix
• CPC Class Codes: H01Q 9/0428 radiating a circular polarised wave
• CPC Class Codes: H01Q 9/045 with particular feeding means for circular polarisation H01Q9/0428
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04L 5/08 each combination of signals in different channels being represented by a fixed frequency
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex

Abstract

A radio frequency identification (RFID) system for frequency multiplexing includes, in one exemplary embodiment, and RFID interrogator configured for generating an RFID signal, wherein a channel frequency of the RFID signal changes over time; a first narrow band antenna, characterized by a first passband, the first passband corresponding to a first range of frequencies; a second narrow band antenna, characterized by a second passband, the second passband corresponding to a second range of frequencies, wherein the second range of frequencies differs from the first range of frequencies, whereby the second passband differs from the first passband; and first and second feed lines configured for feeding the RFID signal to each of the first and second narrow band antennas, respectively. Other embodiments include systems and methods including similar and different RFID components and aspects for frequency multiplexing.

Claims

1. A system comprising:

an RFID interrogator configured for generating an RFID signal, wherein a channel frequency of the RFID signal changes over time;

a first narrow band antenna, characterized by a first passband, the first passband corresponding to a first range of frequencies;

a second narrow band antenna, characterized by a second passband, the second passband corresponding to a second range of frequencies, wherein the second range of frequencies differs from the first range of frequencies, whereby the second passband differs from the first passband; and

first and second feed lines configured for feeding the RFID signal to each of the first and second narrow band antennas, respectively,

wherein the first narrow band antenna is configured to transmit a first electromagnetic wave in response to and at the channel frequency of the RFID signal fed thereto, if the channel frequency of the RFID signal falls within the first passband, and

wherein the second narrow band antenna is configured to transmit a second electromagnetic wave in response to and at the channel frequency of the RFID signal fed thereto, if the channel frequency of the RFID signal falls within the second passband.

2. The system according to claim 1, wherein each of the first and second narrow band antennas is a respective microstrip antenna.

3. The system according to claim 1, wherein the first and second narrow band antennas and the first and second feed lines are configured such that the further the channel frequency of the RFID signal falls outside of the first passband, the more closely the first narrow band antenna appears as an open circuit to the RFID signal and the more closely an apparent impedance presented by the first feed line to the RFID signal approaches an infinite impedance, and the further the channel frequency of the RFID signal falls outside of the second passband, the more closely the second narrow band antenna appears as an open circuit to the RFID signal and the more closely an apparent impedance presented by the second feed line to the RFID signal approaches an infinite impedance.

4. The system according to claim 1, wherein the first electromagnetic wave has a first polarization, and the second electromagnetic wave has a second polarization, the first polarization and the second polarization being characterized by different orientations.

5. The system according to claim 1, wherein the first feed line feeds the RFID signal to the first narrow band antenna at a first edge of the first narrow band antenna, the second feed line feeds the RFID signal to the second narrow band antenna at a second edge of the second narrow band antenna, the first edge of the first narrow band antenna orthogonal to the second edge of the second narrow band antenna.

6. The system according to claim 1, wherein the first narrow band antenna is rotated by 90 degrees relative to the second narrow band antenna, whereby the first electromagnetic wave has a first polarization, and the second electromagnetic wave has a second polarization, the first polarization and the second polarization being orthogonal to one another.

7. The system according to claim 1, further comprising a printed filter, a lumped element filter, or a surface acoustic wave filter configured for filtering the RFID signal based on frequency.

8. The system according to claim 1, wherein the RFID interrogator is further configured to receive an electromagnetic signal transmitted by an RFID tag in response to the first or second electromagnetic wave transmitted by the first or second narrow band antenna, respectively.

9. A system comprising:

an enclosure;

an RFID interrogator configured for generating an RFID signal, wherein a channel frequency of the RFID signal changes over time;

a first narrow band antenna, coupled to the enclosure, characterized by a first passband, the first passband corresponding to a first range of frequencies;

a second narrow band antenna, coupled to the enclosure, characterized by a second passband, the second passband corresponding to a second range of frequencies, wherein the second range of frequencies differs from the first range of frequencies, whereby the second passband differs from the first passband; and

first and second feed lines, configured for feeding the RFID signal to each of the first and second narrow band antennas, respectively,

wherein the first narrow band antenna is configured to transmit a first electromagnetic wave in response to and at the channel frequency of the RFID signal fed thereto, if the channel frequency of the RFID signal falls within the first passband, and

wherein the second narrow band antenna is configured to transmit a second electromagnetic wave in response to and at the channel frequency of the RFID signal fed thereto, if the channel frequency of the RFID signal falls within the second passband.

10. The system according to claim 9, wherein each of the first and second narrow band antennas is a respective microstrip antenna.

11. The system according to claim 9, wherein the first and second narrow band antennas and the first and second feed lines are configured such that the further the channel frequency of the RFID signal falls outside of the first passband, the more closely the first narrow band antenna appears as an open circuit to the RFID signal and the more closely an apparent impedance presented by the first feed line to the RFID signal approaches an infinite impedance, and the further the channel frequency of the RFID signal falls outside of the second passband, the more closely the second narrow band antenna appears as an open circuit to the RFID signal and the more closely an apparent impedance presented by the second feed line to the RFID signal approaches an infinite impedance.

12. The system according to claim 9, wherein the first electromagnetic wave has a first polarization, and the second electromagnetic wave has a second polarization, the first polarization and the second polarization being characterized by different orientations.

13. The system according to claim 9, wherein the first feed line feeds the RFID signal to the first narrow band antenna at a first edge of the first narrow band antenna, the second feed line feeds the RFID signal to the second narrow band antenna at a second edge of the second narrow band antenna, the first edge of the first narrow band antenna orthogonal to the second edge of the second narrow band antenna.

14. The system according to claim 9, wherein the first narrow band antenna is rotated by 90 degrees relative to the second narrow band antenna, whereby the first electromagnetic wave has a first polarization, and the second electromagnetic wave has a second polarization, the first polarization and the second polarization being orthogonal to one another.

15. The system according to claim 9, further comprising a printed filter, a lumped element filter, or a surface acoustic wave filter configured for filtering the RFID signal based on frequency.

16. The system according to claim 9, wherein the RFID interrogator is further configured to receive an electromagnetic signal transmitted by an RFID tag in response to the first or second electromagnetic wave transmitted by the first or second narrow band antenna, respectively.