Using compact structure to improve the defect of traditional transmission line filter which size is too big or transmission line is too long. Two special structures are used to implement the filter that is smaller or superior characteristic. One of the two structures is called DGS that etched defect in the ground plane. The etched lattice shape for the transmission line consists of narrow and wide etched areas in backside metallic ground, which give rise to increasing the effective capacitance and inductance of a transmission line, respectively. Thus, by using this character, the low-pass filters are designed and implemented easily. Another structure is coupled of microstrip square open-loop resonators. First, the coupling coefficients of the three basic coupling structures versus distance between adjacent resonators and different offset is established by means of three-dimensional field analysis methods. Then, the band-pass filter will be implemented by the combination of three basic coupling structures. Finally, two low-pass filter which have cutoff frequency 5.4GHz¡B2.26GHz and a four-pole band-pass filter are designed and fabricated. All theoretical and experimental performance is presented.