Microstrip bimodule band-pass filter based on DGS (defected ground structure) square-ring resonator

The invention discloses a microstrip bimodule band-pass filter based on a DGS (defected ground structure) square-ring resonator, in order to mainly solve the problems that the traditional microstrip bimodule filter is narrower in band width, and the transmission zero is difficult to control. The filter comprises a pair of an input/output 'T'-shaped feeder lines (11), a microstrip medium substrate (12) and a square bimodule resonator (18), wherein a square ring (14) is etched on a metal grounding plate (13) below the microstrip medium substrate (12); each step impedance branch knot (15) is etched at the middle parts of the four edges of the square ring; each paster (16) is etched in the four corners of the square ring (16), thus a DGS square ring bimodule resonator (18) is formed. The pair of the input/output 'T'-shaped feeder lines (11) is vertically placed above the microstrip medium substrate with each other, and extends into the resonator in parallel for power feed. According to the invention, external coupling can be intensified, band width can be expanded, symmetrical and unsymmetrical high-inhibition band pass filter frequency response is realized, and the filter can be used for wireless communication systems.