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.

Amorphous WO3 thin films designed as gigahertz/terahertz dielectric lenses

Herein, tungsten oxide thin films comprising excess oxygen are treated as optical resonator suitable for gigahertz/terahertz applications. WO 3 thin films which are prepared by the thermal evaporation technique under a vacuum pressure of 10 -5 mbar are structurally, compositionally and optically evaluated. The amorphous WO 3.33 films which showed high transparency permit electronic transitions within an indirect allowed energy band gap of 3.05 eV. The band gap comprised energy band tails of width of 190 meV. Four dominant dielectric resonators centered in the infrared (IR), visible (VIS) and ultraviolet (UV) ranges of light are detected. Analysis of the optical conductivity in accordance with the Drude-Lorentz approaches have shown that the drift mobility of free holes in this amorphous layer can be as large as 5.61 cm 2 /Vs an as low as 1.59 cm 2 /Vs when exposed to IR and UV light signals, respectively. In addition, the gigahertz/terahertz cutoff frequency ( ) spectra demonstrated values in the gigahertz frequency domain when exposed to IR light. Excitations with light signals in the VIS and UV spectral ranges allow values that extends from 0.7-40.0 THz. The wide range of tunability of the WO 3 dielectric resonators nominates them as dielectric lenses suitable for optical communications.