Miniaturization of hairpin bandpass filters using high-permittivity substrate.

The miniaturization of hairpin bandpass filters by employing two high-permittivity ceramic substrates (with respective dielectric constants of 9.7 and 20) are investigated. Microwave dielectric ceramics with high permittivity are commonly applied in several microwave communication components. With the advantages of compact size, high-permittivity ceramics can be used as the substrate for bandpass filters. Moreover, the fundamental characteristics of newly developed compact stepped-impedance hairpin resonators with parallel coupled lines have also been described and applied to the design of bandpass filters. In this paper, the designed mixed-coupled structures are simulated using an IE3D simulator. The responses of the fabricated filters using Al2O3 (ℇr = 9.7, Q × f = 350000 GHz) and MgNb2O6 (ℇr = 20, Q × f = 110000 GHz) ceramic substrates are designed at a center frequency of 2 GHz. The compact size and performance of this class of filters are demonstrated. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 222–225, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20776 [ABSTRACT FROM AUTHOR]