A new class of Radio Frequency IDentification (RFID) tags, namely the three-dimensional (3D)-printed chipless RFID one, is proposed, and their performance is assessed. These tags can be realized by low-cost materials, inexpensive manufacturing processes and can be mounted on metallic surfaces. The tag consists of a solid dielectric cylinder, which externally appears as homogeneous. However, the information is hidden in the inner structure of the object, where voids are created to encrypt information in the object. The proposed chipless tag represents a promising solution for anti-counterfeiting or security applications, since it avoids an unwanted eavesdropping during the reading process or information retrieval from a visual inspection that may affect other chipless systems. The adopted data-encoding algorithm does not rely on On–Off or amplitude schemes that are commonly adopted in the chipless RFID implementations but it is based on the maximization of available states or the maximization of non-overlapping regions of uncertainty. The performance of such class of chipless RFID tags are finally assessed by measurements on real prototypes.

A method for detecting radio frequency chipless RFID tags is presented. The tags are interrogated through an open waveguide from a very short distance in order to realize a quasi-guided system which does not need any calibration procedure. The application scenario is to place the tag inside a plastic or cardboard box and read it by placing the waveguide on the external side of the box in the same position of the tag. The tag is designed to be commensurate with the waveguide in order to guarantee the correct operation of the quasi-guided reading system. A prototype of the tag has been fabricated and some measurements to assess positioning error have been carried out.

In this paper, a low-cost chipless reader for detecting depolarizing tags is described. The reader operates in the frequency band (2–2.5) GHz, and it is compact and integrated in a single board. The reader architecture and its transmitting and receiving antennas are presented. Reader antennas comprise of two orthogonally placed, E-shaped patches with a decoupling below −35 dB. The reader performance is evaluated on a four-bit tag formed by four obliquely placed dipoles on top of a metallic ground plane.

This work summarizes the main outcomes of the EMERGENT project that was mainly focused on the design of chipless RFID sensors and their realization on green substrates. Three different sensors are presented for monitoring humidity, temperature and breathing.