The concept of pulse-position modulation coding based on group delay engineered microwave C-section dispersive delay structures (DDSs) is experimentally demonstrated as a novel chipless radio frequency identification (RFID) system. The tags consist of various DDSs whose group delay responses can be engineered to provide different pulse-position modulation (PPM) codes. A 3-bit system is presented with an RFID reader and various different DDS-based tags. The proposed concept offers system simplicity, frequency scalability, and M-ary coding capability for large ID coding diversity.