A Wideband Absorptive Common-Mode Filterby Utilizing Meandered Rail-Shaped Slot Resonator

The paper presents a miniaturized bidirectional absorptive common-mode filter (A-CMF) with capability of broadband common-mode (CM) noise suppression. The proposed A-CMF is designed by etching a rail-shaped slot in the ground plane. To reduce the resonator size by up to 18.6 %, two bridge-like slotlines are meandered to connect two back-to-back C-like slots. By loading several lumped resistors in the rail-shaped slots, reflected common-mode noise can be absorbed efficiently. According to measured results of the proposed A-CMF module, the absorption rate ranges from 2.17 to 4.14 GHz (62.5%) within a 90% absorption rate. Additionally, a CM noise suppression bandwidth of 88.6 % (1.93 to 5.00 GHz) is observed with a rejection level of better than 10 dB. Good agreement between the measured and simulation results can be observed.