Design of Dual-Band Bandpass Filter With Simultaneous Narrow- and Wide-Bandwidth and a Wide Stopband

Min-Hang Weng,Shoou-Jinn Chang,Siang-Wen Lan,Ru-Yuan Yang

doi:10.1109/access.2019.2946302

Min-Hang Weng, Shoou-Jinn Chang + Show 2 more

Open Access

https://doi.org/10.1109/access.2019.2946302

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Abstract

This paper presents a novel dual-band bandpass filter with narrow and wide passband simultaneously and a wide stopband. The dual-band bandpass filter is implemented using a stepped-impedance ring loaded resonator (SIRLR). The properties of the SIRLR are analyzed in detail based on the even- and odd-mode equivalent circuits. Resonant modes, excited by SIRLR, can be controlled and used to form a narrow passband at 2.4 GHz with bandwidth ratio of 8% and a wide passband from 3 to 5 GHz, with insertion losses less than 1.5 dB for both two passbands. Three transmission zeros are created near the passband edge to improve the passband selectivity and achieve a sharp cutoff skirt (over 60 dB/GHz). In addition, for wide stopband consideration, rectangular stub loaded resonators (RSLRs) are tapped on the input and output ports of above dual-band filter without destroying the dual-band performances. Thus, the proposed dual-band filter with a wide stopband region from 5 to 20 GHz with a rejection level of 25 dB is also achieved. The measured results show a good agreement with the simulated results.

Highlights

In recent years, for the demand of high-quality service, multi-band mobile equipments have attracted much interest for use in wireless communications applications, such as the Global System for Mobile communications (GSM), IEEE 802.11 wireless local area networks (WLANs) and ultra-wide band (UWB) system
The dual-band responses for WLAN and UWB uses are excited merely by one stepped-impedance ring loaded resonator (SIRLR)
In comparison with above mentioned design, we introduced novel ratio parameters, which are related to the physical dimensions of the SIRLR, to control each mode of SIRLR much more accurately

Summary

INTRODUCTION

For the demand of high-quality service, multi-band mobile equipments have attracted much interest for use in wireless communications applications, such as the Global System for Mobile communications (GSM), IEEE 802.11 wireless local area networks (WLANs) and ultra-wide band (UWB) system. To avoid the interference with other communication systems, a wide stopband design for the filter is always required In this design, a novel dual-band bandpass filter having a narrow-band and wide-band response and with an extended stopband is shown. The dual-band responses for WLAN and UWB uses are excited merely by one stepped-impedance ring loaded resonator (SIRLR). It is composed by one SIRLR, and a pair of RSLR.

EQUIVALENT CIRCUIT

RESONANT CHARACTERISTIC

EXPERIMENT RESULT AND DISSCUSION

CONCLUSION