A dual-band filter using stepped-impedance resonators with coupled-feed lines

In this paper, a dual-band filter using stepped-impedance resonators with coupled-feed lines is proposed to develop the microstrip open loop resonators dual-band filter. The dual-band filter is based upon the design of two filters independently; one of them meeting the desired performance at 900 MHz and the other desired performance at 1800 MHz. The two filters can be combined using the coupled feed lines. The measured insertion losses are better than 3.0 dB for the two channels. It is very useful for applications in mobile communication systems.