Synthesis Design of Quasiplanar SEMCP Bandpass Filters With Metal-Integrated Suspended Line Technology for 5G Application

This article presents two directly coupled narrow bandwidth separate electric and magnetic coupling paths (SEMCPs) bandpass filters (BPFs) based on metal integrated suspended line (MISL) technology for 5G application. Novel types of dual-end shorted folded half-wavelength stepped impedance resonators (HSIR) that do not require additional structures to produce flexible transmission zeros (TZs) are presented. The all-metal quasiplanar structure can achieve both the complete elimination of dielectric losses and the miniaturized design of filters. To show the advantages of the MISL resonators in terms of low loss and the ability to achieve flexible TZs, we analyze the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i>-factor of the single resonator structure and the mechanism of TZ production. We have designed a fourth-order filter with in-line topology and a sixth-order filter containing two triplets topologies, both of which produced N-1 TZs. To ensure that the processed filters work well, high-precision laser technology is applied to the production of filters. The test results show good consistency with the theoretical expectations and simulation results.