Multi-antenna element systems and related methods

1. A radio frequency identification (RFID) tag comprising:

an antenna system comprising:

a ground plane;

a first antenna element on a first side of the ground plane; and

a second antenna element on a second side of the ground plane opposite first antenna element, the second antenna element being electrically coupled to the first antenna element at a common feed point, wherein the first antenna element and the second antenna element each receive radio frequency signals; and

a first radio frequency identification circuit coupled to the first antenna element and the second antenna element at the common feed point.

2. The RFID tag as defined in claim 1 wherein each of the first and second antenna elements comprises a patch of conductive material having a length and a width equal to or smaller than a length and width of the ground plane.

3. An apparatus comprising:

a first radiative patch;

a second radiative patch, wherein the second radiative path is electrically coupled to the first radiative patch, the first radiative patch and the second radiative patch sharing a common feed point for receiving a radio frequency signal that drives the first radiative patch and the second radiative patch; and

a ground element disposed between the first and second radiative patches and electrically isolated from the radiative patches.

4. The apparatus as defined in claim 3 further comprising a first layer of dielectric material coupled between the first radiative patch and the ground element.

5. The apparatus as defined in claim 4 further comprising a second layer of dielectric material coupled between the second radiative patch and the ground element.

6. The apparatus as defined in claim 3 further comprising a radio frequency identification circuit coupled to both the first and second radiative patches, and when an interrogating signal is incident upon at least one of the radiative patches, the radio frequency identification circuit responds with a value.

7. The apparatus as defined in claim 6 wherein the radio frequency identification circuit responds with the value by selective detuning of at least one of the radiative patches.

8. The apparatus as defined in claim 3 wherein the first radiative patch comprises a centroid axis normal to a plane defined by the first radiative patch; and wherein the second radiative patch comprises a centroid axis normal to a plane defined by the second radiative patch and substantially coaxial with the centroid axis of the first radiative patch.

9. A system comprising:

a first means for receiving and sending electromagnetic waves;

a second means for receiving and sending electromagnetic waves, the first and second means for receiving sharing an internally disposed means for insertion of a driving signal; and

a means for limiting directionality of electromagnetic waves, the means for limiting being disposed between the first and second means for receiving, and the means for limiting being electrically isolated from the first and second means for receiving;

wherein the first and second means for receiving are each configured to be driven at the means for insertion with a radio frequency signal.

10. The system as defined in claim 9 further comprising:

a first means for responding to interrogating signals, the first means for responding coupled to the first means for receiving; and

a second means for responding to interrogating signals, the second means for responding coupled to the second means for receiving.

11. The system as defined in claim 10 wherein the first and second means for responding, in response to interrogating signals, one or more selected from the group consisting of: respond identically; or respond such that the first means for receiving is distinguishable from the second means for receiving.

12. The system as defined in claim 9 further comprising a means for responding to interrogating signals, the means for responding coupled to both the first and second means for receiving.