Design of Bandpass Filter Based on Metamaterial Concepts

A design of an ultra-wideband (UWB) bandpass filter (BPF) is presented depending on the composite right/left handed-transmission line (CRLH-TL) basis. The interdigital (ID) coupled lines and complementary split ring resonators (CSRRs) are the tools used to realize an UWB microwave filter with an appreciable size reduction and better performance. The bandwidth resulted from this filter is 5.6 GHz operating at 3.2 GHz center frequency. The interdigital elements are connected to the input and output ports through square closed rings in the upper side of the microstrip line, whereas the CSRRs are etched in the ground of the microstrip line. All components contribute together to get metamaterial (MTM) media containing negative permittivity and negative permeability. The simulated results show that the filter has a flat insertion loss of less than 1 dB with an acceptable return loss performance in the frequency range (0.4-6) GHz. The achieved quality factor is equal to 0.57 and the fractional bandwidth is over 100 %.