Chipless RFID using stacked multilayer patches

Stacked multilayer patch antennas as a candidate for sub-cent chipless RFID tags is proposed. The magnitude of scatter from such a structure ideally has negligible variation over frequency, but has predictable phase (delay) variation at pre-determined resonant frequencies. Such scattering structures can be modeled as all-pass networks and are expected to be more robust than non all-pass structures in presence of multi-path and clutter. Due to the simplicity of geometry, such tags have a potential for customer site fabrication using machines simpler than inkjet printers. All-pass scatterers can also be used to construct sensors.