A Multilayered Parallel Coupled Microstrip Bandpass Filter With Embedded SIR Cells to Have a Broad Upper Rejection Band |
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Authors: | Kuan H Lin Y-L Yang R-Y Chang Y-C |
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Affiliation: | Department of Technology Electro-Optical Engineering, Southern Taiwan University, Tainan, Taiwan, R. O. C.; |
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Abstract: | This paper proposes a parallel coupled microstrip bandpass filter (BPF) with folded stepped impedance resonator (SIR) cells on the middle layer for spurious suppression. The folded SIR cells on the middle layer create a wide stopband by canceling the second and third harmonics of the parallel coupled microstrip BPF with suppression of over $-$50 and $-$30 dB, respectively. By selecting properly the impedance ratio (R) and physical length ratio $(alpha)$ of the folded SIRs, the parallel coupled BPF with a wide stopband can be implemented without causing a package problem of degrading the complete ground plane. The proposed BPF is designed and fabricated. Good agreement between the electromagnetic (EM) simulation and measurement is obtained. |
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