LAUSR

The paper proposes a miniaturized strip-line absorptive common-mode filter using a novel and ingenious defected ground structure (DGS). The proposed filter is bidirectional and owns an ultrawide absorption band to stop common-mode noise. Its fractional bandwidth is as large as 147%. In addition, the filter allows the total transmission of differential signals up to about 15 GHz determined by the 3-dB cutoff frequency. Both the noise absorption and signal transmission bandwidths are never achieved in literatures before. An equivalent circuit model and the design principle are offered. According to these, the filter prototype with a total area of 1.1% of the square of the wavelength at the lowest frequency of the absorption band is designed and implemented. The measured results verify the design and also demonstrate the claimed performance.