Multilayer metallic filters for Q/V band IMUX

Current designs of space IMUX filters are based on dual-mode circular waveguide cavities, on dielectric resonators or, at the lower end of the frequency spectrum, on coaxial resonators. This paper presents a new kind of IMUX filter aimed at high operating frequencies (Ka, Q, and V bands) which was developed in the frame of an ESA funded study named KALOS-DEVAQ. The new filter implements a quasi-elliptic frequency response and is characterized by simple geometry. The mechanical structure is composed of stacked metallic plates and it is well suited to be manufactured, at a low cost, with high accuracy. Despite the lower unloaded Q factor, the new configuration allows achieving a comparable flatness of insertion loss and group delay, thanks to the application of the pre-distortion technique. The increased insertion loss does not affect the system performances because it can be compensated by the amplification stages in the RF chain.

Phononic Coupled-Resonator Waveguide Micro-Cavities

Phononic coupled-resonator waveguide cavities are formed by a finite chain of defects in a complete bandgap phononic crystal slab. The sample is machined in a fused silica plate by femtosecond printing to form an array of cross-shape holes. The collective resonance of the phononic cavities, in the Megahertz frequency range, are excited by a piezoelectric vibrator and imaged by laser Doppler vibrometry. It is found that well-defined resonant cavity modes can be efficiently excited, even though the phononic cavities are distant by a few lattice spacings and are only weakly coupled through evanescent elastic waves. The results suggest the possibility of engineering the dynamical response of a set of coupled phononic cavities by an adequate layout of defects in a phononic crystal slab.