Patent ID: 7551140

Claim:
A radio frequency identification (RFID) device, comprising: a quadrature hybrid coupler having first, second, third, and fourth ports, wherein the first port receives an input radio frequency (RF) signal, the second port outputs a first RF output signal, and the third port outputs a second RF output signal, wherein the second RF output signal is shifted in phase by 90 degrees relative to the first RF output signal; a a termination element coupled to the fourth port; a circuit board, wherein the termination element and quadrature hybrid coupler are mounted to the circuit board; a back plate having a centrally-located opening, wherein the circuit board is mounted in the centrally-located opening; and a patch antenna having a first point coupled to the first RF output signal and a second point coupled to the second RF output signal, wherein the patch antenna radiates a circularly polarized RF signal, wherein the patch antenna is planar and is positioned parallel to the circuit board.