Triple-Mode Substrate Integrated Coaxial Resonator Based Bandpass Filter Featuring Flexible Transmission Zeros and Adjustable Bandwidth
Idury Satya Krishna, Soumava Mukherjee
Abstract
This communication presents substrate integrated coaxial resonator (SICR) based triple-mode bandpass filters designed for K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">u</sub> -band. A self-shielded SICR based third-order filter is realized using two planar coaxial resonators (SICR) embedded in a substrate integrated waveguide cavity (SIW). Merging the TEM based mode of two SICR's with TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">101</sub> mode of SIW significantly enhances the bandwidth in a compact size. A novel topology realized using short circuited metallic via connecting to the top conducting plane through a metal strip demonstrates high degree of flexibility in positioning the transmission zeros to improve the selectivity as well as extend the out-of-band rejection of proposed filter. The three experimental prototypes devised for K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">u</sub> -band with fractional bandwidth more than 23% demonstrate multiple transmission zeros for good selectivity and out-of-band rejection with low insertion loss in a compact form factor.