A scalable modular antenna configuration to extend the detection volume of a near-field UHF-RFID desktop reader

A modular combination of a resonating circular ring slot antenna and a spiral Travelling Wave Antenna (TWA) is proposed in this paper for NF UHF RFID desktop reader applications. The spiral TWA is able to generate strong and uniform fields just above the antenna surface. The circular ring slot antenna is serially-fed by the TWA and it is used to extend the read range up to the radiative near field region. In order to make the overall antenna scalable, the spiral TWA is extended beyond the slot antenna, so allowing to cover a large and arbitrarily shaped area.