This paper presents a time domain analysis of a backscatter based multiresonator chipless RFID tag. A model for the tag and its theory of operation is presented. The two components of the backscattered signal, the structural mode and the information carrying antenna mode, are clearly identified and shown in the time domain signal. The theoretical derivations are verified through simulation results. The proposed method eliminates the dependence of frequency signature based tags on calibration tags for proper operation.