In this paper, two high-quality substrates with low dielectric loss tangent were used to design chipless RFID tags operating at the 1.75 GHz to 3.0 GHz frequency band, fabricated using subtractive and additive technologies processes, depending on the substrate used. Two models of chipless RFID tags were designed: an 8-bit L-Shaped Dipole tag using Rogers RT/duroid® 5880 laminated and fabricated using a subtractive process through a milling machine, and a 9-bit I-Shaped Slot tag designed on Kapton® HPP-ST and fabricated by an additive process using an inkjet with nanoparticle-based silver ink. The simulated and experimental RCS of these tags are presented, allowing a comparison of their performance and a discussion of the viability of using printed conductive layers to fabricate chipless RFID tags