A miniaturized dual-mode bandpass filter with a wide stopband realized on the ultra-thin flexible substrate

In this paper, a miniaturized dual-mode bandpass filter (BPF) with a wide stopband by using a modified ring dual-mode resonator is proposed and realized on the ultra thin (100 μm) flexible liquid-crystal-polymer (LCP) substrate, which can be applied to the next generation flexible electronics. The proposed BPF is mainly formed by using a modified ring dual-mode resonator and centered at f₀ of 2.4 GHz, which is used for wireless local area network (WLAN) IEEE 802.11b/g. The filter sample is fabricated and has a size reduction of 59.5%, compared to the conventional square ring dual-mode BPF, and a wide stopband to 4.7 f₀. The measured results are in good agreement with the full-wave simulation results.