ANTENNA ARRAY IN AN RFID SYSTEM

摘要

In accordance with the present invention, a general antenna system is disclosed suitable for applications in which an RFID Tag passes by an Interr ogator. We then disclose a specific antenna design that uses a single planar antenna fortransmit and a multi-element planar antenna array fo r receive. The multi-elementplanar antenna array is spaced such that each of the planar elements is four inches apart, center-to-center, thus defining a narrow 30.degree. receive beamwidth in the horizontal plane. The vertical receive bandwidth is much greater than 30.deg ree., facilitating the Interrogator receiving signals at a variety of elevations. Furthermore, a multi-way microstrip combiner is used to sum the signals received from each of the pla nar antenna. To block interference from the transmit antenna and to improve rec eivesensitivity, this multi-way microstrip combiner is s hielded using, in one embodiment, copper tape along its edges. In a specific embodiment, a four element receiv e antenna design is disclosed.