In this paper, complementary split ring resonators (CSRRs) as band-stop elements are used in combination with coupled microstrip lines as high and low pass elements to design and fabricate very compact bandpass filter (BPF) having controllable characteristics. The proposed filter provides several advantages such as compactness (occupying area less than 0.1λg × λg in which λg is calculated at center frequency of pass band), sharp rejection, low insertion loss (IL less than -8.5 dB in all of the bandwidth), good return loss (RL 3-dB bandwidth of roughly 2 GHz from 0.7 GHz to 2.7 GHz i.e. more than 115% FBW) and low cost. Defected Microstrip and Ring Resonator Structures have been used for eliminating the created spurious pass band in upper frequencies. The simulation results have been done with full-wave softwares i.e. CST and HFSS by time and frequency domain solvers, respectively. Also, the equivalent lossless lumped circuit of total structure has been obtained and simulated by ADS software. These simulated results show good agreements with experimental ones.
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