In this letter, compact-balanced bandpass filter (BPF) and filtering crossover are proposed with intrinsic common-mode (CM) suppression by using a single-layered substrate-integrated waveguide (SIW) cavity. The SIW cavity with low profile is TEn0m mode resonator, which has only one nonzero electric field component. Hence, it is also a natural frequency selection device of the differential signal. Meanwhile, the CM signal cannot excite the cavity due to the characteristics of perfect electric conductor (PEC) and perfect magnetic conductor (PMC). For the design of the balanced SIW BPF, the differential-mode (DM) equivalent half circuit is a single-ended SIW filter with height halved. Furthermore, the microstrip differential transition structure is designed to excite the SIW cavity and has little conversion between DM and CM. On this basis, a compact SIW-balanced filtering crossover is proposed using the degenerate modes TE102 and TE201. Finally, compact third-order SIW-balanced BPF and filtering crossover are designed and fabricated, and the measured results show good agreement with the simulated ones.

中文翻译：

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使用单层 SIW 腔的具有固有共模抑制功能的紧凑型平衡 BPF 和滤波分频器

在这封信中，通过使用单层衬底集成波导 (SIW) 腔，提出了具有固有共模 (CM) 抑制的紧凑平衡带通滤波器 (BPF) 和滤波交叉。低剖面的 SIW 腔是 TEn0m 模式谐振器，它只有一个非零电场分量。因此，它也是差分信号的固有频率选择器件。同时，由于理想电导体（PEC）和理想磁导体（PMC）的特性，CM信号不能激发腔体。对于平衡 SIW BPF 的设计，差模 (DM) 等效半电路是高度减半的单端 SIW 滤波器。此外，微带差分过渡结构旨在激发SIW腔，并且在DM和CM之间几乎没有转换。以这个为基础，使用退化模式 TE102 和 TE201 提出了一种紧凑的 SIW 平衡滤波交叉。最后，设计并制作了紧凑型三阶SIW平衡BPF和滤波分频器，测量结果与仿真结果吻合良好。