This paper presents a new radio frequency identification(RFID) tag that based on frequency domain coding. This tag consists of a certain number of square patch resonators placed on a certain substrate. Due to the symmetry of its structure, the tag can be read from any orientation with the reader antennas. The Radar Cross Section(RCS) responding of the tag over the FCC authorizes UWB communications ranges from 3.1 to 10.6 GHz. A better frequency identification can be obtained after using the improved Matrix Pencil Method(MPM) to extract the resonance points and differential encoding algorithm analysis. Compared with the previous chipless RFID tags，a capacity of 16 bit can be reached. It has a relatively high coding capacity and better direction independent. It is more suitable for the current market demand.