MICROWAVE NARROWBAND FILTERS USING SINGLE AND STACKED COAXIAL LINES
A. JAIMES-VERA, I. LLAMAS-GARRO, A. CORONA-CHAVEZ, I. ZALDIVAR-HUERTA

Abstract. This paper presents two suspended rectangular coaxial transmission line filters suitable for 3D MEMS fabrication. The rectangular coaxial microwave transmission line is made of metal only, resulting in a non dispersive line with no dielectric losses. Two microwave filters are presented using the rectangular coaxial transmission line; the designs use a compact resonator suspended by a short circuit. The suspended resonator has been used to design a chebyshev filter inside a single coaxial cable, where a prototype to demonstrate this topology is presented. The presentation of a second filter using two vertically stacked coaxial cables in order to produce a quasielliptic filter response is discussed, where the couplings between the coaxial cables is achieved using a coupling iris in the common coaxial ground plane between lines. The proposed resonator is for use in microwave narrowband applications, the two designs presented in this paper have a 4% fractional bandwidth with central frequencies at around 9 Ghz.