基于微带三模谐振器的超宽带带通滤波器设计

提出一种基于微带三模谐振器的超宽带带通滤波器设计.该滤波器由一个中心加载阶跃阻抗开路枝节的三模谐振器,及两组用于抑制谐波的新型哑铃型缺陷地结构组成.使用交指型馈电方式及在馈电处的地板开槽实现超宽带需要的的强耦合,利用缺陷地结构抑制高次谐波实现良好的阻带特性.仿真结果表明,所设计的滤波器通带3 dB相对带宽达到80％(4.06～9.48 GHz),通带内插入损耗小于0.58 dB,回波损耗大24 dB,通带外10 dB阻带覆盖到30 GHz,通带两侧附近均有一个传输零点,获得了陡峭的通带边缘,较好地实现了美国联邦通信委员会(FCC)授权的超宽带通信系统的频谱使用要求.该滤波器结构简单,谐振器自身尺寸小于中心频率下0.5λg×0.5λg.最小带线和最小缝隙宽度均不小于0.1 mm,易于低成本加工,具有较高的实用价值.

Design ofultra wideband bandpass filter usingmicrostripthree moderesonator

This paper proposed a novalutral-wideband (UWB) bandpass filter (BPF) based on miscrostrip multi-mode resonator.The filter consists of a miscrostripstub-loaded three-mode resonator and a pair of novel dumbbell-shaped defected-ground structure for harmonic suppression.In addition,the stub of the three-mode resonator is modified into a step-impedance stub to achieve the desired band width.A cross-finger feeding structure with a background-aperture compensation technique is also used in this filter design to strengthen the energy coupling.The simulatedresults of the proposed UWBBPF show a 3 dB passband with a fractional bandwidth over 81.8％ (within 4.04～ 9.63 GHz),insertion loss lower than 0.2 dB,return loss over 24 dB and 10 dB stopband extending to higher than 30 GHz.The passband of the BPF also shows a very sharp skirt property because of the transmission zeros at both the lower and upper side of the passband.The UWB spectrum mask issued by the Federal Communication Commission(FCC) is satisfied well by the designed BPF.The structure of the proposed UWB BPF is quite compact (smaller than 0.5λg × 0.5λg at the central frequency) and easy to fabricate at low cost because its minimum strip-width and minimum gapwidth are both 0.1 mm.