Design of a dual-band bandpass filter with miniaturization and high selectivity
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摘要: 为了满足C波段卫星通信系统的应用需求,提出了一种具有小型化与高选择性的双频带通基片集成波导滤波器. 滤波器第一通带由蚀刻在四分之一模基片集成波导腔顶层的L型谐振槽提供,第二通带由新型左右手结构提供. 其中L型谐振槽可以充当四分之一波长谐振器,激励腔内基本模式产生低频处的响应;新型左右手结构较传统结构增大了叉指电容值,降低了谐振频率. 通过仿真优化和测试,双频带通滤波器的中心频率为3.9 GHz和6.2 GHz,相对带宽为3.3%和2.1%,通带之间的衰减优于70 dB,且在通带外存在三个传输零点,具有良好的频率选择性. 表明了所提滤波器具有体积小、选择性高的特性,非常适合集成于卫星通信前端系统中.Abstract: In order to meet the application requirements of C-band satellite communication system, a dual-band bandpass substrate integrated waveguide filter with miniaturization and high selectivity is proposed. The first passband of the filter is provided by an L-shaped resonant slot etched in the top layer of the quarter-mode substrate integrated waveguide cavity, and the second passband is provided by a new right/left-handed structure. The L-shaped resonant slot can act as a quarter-wavelength resonator to excite the fundamental mode in the cavity to produce a response at low frequencies; the new right/left-handed structure increases the fork-finger capacitance value compared with the conventional structure, then reduces the resonant frequency. Through simulation optimization and testing, the center frequencies of the dual-band bandpass filter are 3.9 GHz and 6.2 GHz with relative bandwidths of 3.3% and 2.1%, and the attenuation between the passbands is better than 70 dB, and three transmission zeros exist outside the passbands with good frequency selectivity. It is shown that the proposed filter has the characteristics of small size and high selectivity, which is very suitable for integration in the front-end system of satellite communication.
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表 1 滤波器的尺寸
Tab. 1 The size of the filter
mm 参数 取值 参数 取值 $L$ 18.0 $L_1$ 4.5 $W$ 9.0 $L_2$ 7.4 $P$ 6.5 $L_3$ 7.2 $K$ 1.5 $L_4$ 3.0 $O$ 0.8 $W_1$ 0.2 $D$ 0.4 $W_2$ 0.6 $S$ 0.6 -
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