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This work designs miniaturized stub‐type microstrip bandpass filters and develops a novel vertical interconnection scheme in a multilayer structure to design vertically folded filters for size reduction. The current study exploits the fabrication process of low‐temperature cofired ceramic (LTCC) for filter realization and fabricates two LTCC Chebyshev stub‐type filters at 28 GHz and 5.8 GHz to verify effectiveness of the proposed structure with a maximum size reduction of 50%. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1389–1394, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26024

Abstract-This study presents a design of a compact stub-type bandpass filter with capacitively loaded stubs and a fold-back structure. This paper employed the fabrication process of lowtemperature co-fired ceramic (LTCC) for filter realization of a multilayer structure. The proposed filter structure required adding end capacitors to stubs to extend their electrical length, while achieving a length reduction of 30%. This study provided design curves to determine the dimensions of the end capacitor for reaching maximum electrical length extension. In addition, a fold-back configuration was applied to halve the filter size. An experimental filter operating at 5.8 GHz was fabricated and measured to validate the design concept, achieving a highly compact size of 14.3 × 8.2 × 0.76 mm 3 .