Provided is a method for encoding chipless RFID tags in real-time. The method includes exposing a chipless RFID transponder to a conductive material, the RFID transponder comprising an antenna and a plurality of resonant structures, the plurality of resonant structures together defining a first spectral signature. Each of the plurality of resonant structures includes a respective one of a frequency domain. The method also includes depositing a conductive material on at least one of the resonant structures to short the at least one of the resonant structures. The remainder of the plurality of resonant structures that are not shorted by the conductive material define a second spectral signature for the RFID transponder.