Design of dual-mode dual-band microstrip bandpass filter based on Sierpinski fractal geometry

A new dual-mode dual-band bandpass filter (BPF) which is mainly formed by a cross patch resonator based on the second Sierpinski fractal curve geometry is introduced in this article. The different order Sierpinski fractal-based resonators (SFRs) are generated from the cross patch by using an iterative Sierpinski generator method. The small patch which is placed at the corner of the SFR is applied to excite the degenerate modes. By adjusting the size of the patch, two resonant modes are excited and two transmission zeros are generated which further improve the performance of the BPF. Simulated results show that the proposed filter possesses finer frequency response characteristics. Moreover, the proposed filter can be used for Wireless Local Area Networks (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX) applications.