基于SISL的介质填充双通带滤波器设计

为实现滤波器的小型化，基于介质集成悬置线(substrate integrated suspended line, SISL)结构提出了一种介质填充双通带滤波器的设计方案. 首先将高介电常数的介质块填充入SISL的空气腔中，提升SISL的等效介电常数，实现电路的小型化，高介电常数介质块可以直接被SISL固定；然后利用T型结连接两组工作在不同频段的滤波器从而使得两个通带相对独立；最后利用仿真软件进行优化，确定介质填充双通带滤波器的尺寸，并进行加工与测试. 仿真与测试结果表明，二者具有较好的一致性，两个通带频率内的回波损耗均优于15 dB，电路的核心尺寸为0.058λ_g×0.139λ_g(λ_g为SISL在第一通带中心频率处的导波波长). 此双通带滤波器具有小尺寸、自封装等优势，且所有层介质基板均采用低成本的FR4板材，降低了制造成本.

A dielectric-filled dual-band bandpass filter based on SISL technology

This paper proposes a dielectric-filled dual-band bandpass filter (DF-DBBPF) using substrate integrated suspended line (SISL) technology to realize the miniaturization of the filter. In this design, high dielectric constant material is embedded in the SISL air cavity to construct a high equivalent dielectric constant and miniaturize the circuits. The high dielectric constant material is fixed directly by the SISL cavity. Meanwhile, by using T-junctions to design the dual-band bandpass filter, each passband response can be designed independently. With the help of the EM simulation software, all the dimensions are determined and the DF-DBBPF is processed and tested. The simulated and measured results of this design have the same tendency. The return loss of the two passbands are both better than 15 dB and the size of core circuit is only 0.058λ_g×0.139λ_g, which λ_g represents the guided wavelength at the central frequency of the first passband. The DF-DBBPF is with the advantage of compact size and self-packaging. Meanwhile, low-cost FR4 is chosen for all seven substrate boards.