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US 8,077,044 B2Granted
RFID tags with enhanced range and bandwidth obtained by spatial antenna diversity
AssigneeIntermec IP Corp.
InventorsPavel Nikitin, KVS (Venkata Kodukula) Rao, Sander Lam
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Abstract
Spatial antenna diversity is used with RFID tags to reduce sensitivity to multi-path fading. RFID tags can use a single multi-port chip or multiple multi-port chips. The ports of the chip or chips are coupled to separated feedpoints on one or more antennas.
Claims31
An RFID tag comprising:
- a dual-port RFID chip having a first port and a second port, wherein the first port has a first RF terminal and a first ground terminal, and the second port has a second RF terminal and a second ground terminal;
- and
- a shared antenna having a first feedpoint and a second feedpoint,
- wherein the first RF terminal couples to the first feedpoint located at a first point on the shared antenna, the second RF terminal couples to the second feedpoint at a second point a distance away from the first feedpoint on the shared antenna, and the first and second ground terminals couple to approximately a center point on the shared antenna,
- wherein a length of the shared antenna is approximately one wavelength, the first point is approximately one-quarter wavelength from a first end of the shared antenna, and the second point is approximately one-quarter wavelength from a second end of the shared antenna, and
- wherein the dual-port RFID chip and the shared antenna are configured for spatial antenna diversity and configured to reduce sensitivity to multi-path fading in response to a received wireless RFID signal.
3 more elements
An RFID tag comprising:
- at least one RFID chip having multiple ports, wherein each port has an RF terminal and a ground terminal;
- and
- at least one shared antenna having multiple feedpoints, wherein a total number of RF terminals equals a number of feedpoints on the shared antenna, each RF terminal is coupled to a different feedpoint, and each feedpoint is located at a different point on the antenna.
An RFID tag comprising:
- an RFID chip having multiple ports, wherein each port has an RF terminal and a ground terminal;
- and
- multiple antennas each having at least one feedpoint, wherein each feedpoint is at a different location from all other feedpoints, and further wherein each RF terminal is coupled to one of the feedpoints.
An RFID tag comprising:
- multiple RFID chips, wherein each RFID chip has multiple ports, and each port has an RF antenna terminal and a ground terminal;
- and
- an antenna portion, wherein the antenna portion is either:
- multiple antennas each having at least one feedpoint, wherein each feedpoint is at a different location from all other feedpoints, and further wherein each RF terminal is coupled to one of the feedpoints, or
- at least one shared antenna having at least two separated feedpoints, wherein at least two different RF terminals are coupled to the at least two separated feedpoints.
2 more elements
An RFID tag comprising:
- an RFID chip having a frequency-dependent chip reactance;
- and
- a shared antenna having a plurality of feedpoints, wherein each feedpoint has a frequency-dependent feedpoint reactance, and the frequency-dependent chip reactance is substantially matched to each of the frequency-dependent feedpoint reactances at least one frequency.
An RFID tag comprising:
- a dual-port RFID chip having a first port and a second port, wherein the first port has a first RF terminal and a first ground terminal, and the second port has a second RF terminal and a second ground terminal;
- and
- a shared antenna having a first feedpoint and a second feedpoint,
- wherein the first RF terminal couples to the first feedpoint located at a first point on the shared antenna, the second RF terminal couples to the second feedpoint at a second point a distance away from the first feedpoint on the shared antenna, and the first and second ground terminals couple to approximately a center point on the shared antenna.
1 more element
Dependencies are inferred from the claim text.