Compact K-Band Split-Type Dual-Band Bandpass Filter Based on Stepped-Impedance DGS Cells

摘要

In this paper, a K-band split-type dual-band bandpass filter (DBBPF) based on stepped-impedance defected ground structure (DGS) cells is presented. Two sets of stepped-impedance DGSs (i.e., interdigital- and C-shapes) generating two different coupling paths are used to achieve phase cancellation, which provides the in-band transmission zero (TZ) to split the wide passband into two narrower sub-passbands. Besides, as demonstrated through a parametric analysis of the geometry of the proposed DGS cells, all TZs (i.e., in- and out-band) can be finely positioned. To experimentally verify the aforementioned operating mechanisms, a DBBPF operating at 23.3 and 26.7 GHz is proposed and fabricated. Measured results demonstrate the sharp rejection capabilities up to 23 dB between the two passbands in a compact size with a core area of 1.8 mm × 4.1 mm.