ABSTRACT
Organic-inorganic hybrid materials are attractive due to the combination of properties from the two distinct types of materials. In this work, transparent titania-polydimethylsiloxane hybrid materials with up to 15.5 vol. % TiO2 content were prepared by an in situ non-aqueous method using titanium (IV) isopropoxide and hydroxy-terminated polydimethylsiloxane as precursors. Spectroscopy (Fourier transform infrared, Raman, Ultraviolet-visible, ellipsometry) and small-angle X-ray scattering analysis allowed to describe in detail the structure and the optical properties of the nanocomposites. Titanium alkoxide was successfully used as a cross-linker and titania-like nanodomains with an average size of approximately 4 nm were shown to form during the process. The resulting hybrid nanocomposites exhibit high transparency and tunable refractive index from 1.42 up to 1.56, depending on the titania content.
ABSTRACT
In this paper, we present a design and measurements of a five-section bandpass filter with a passband from 96 to 106 GHz. The insertion loss is less than 1.4 dB in the passband, and the rejection is better than 40 dB in the range from 115 to 142 GHz. We use transmission line coupling theory based on Tchebyscheff's synthesis in order to provide an initial guess for the geometrical parameters of the filter such as cavity lengths and coupling widths. The filter is manufactured from brass in two halves in the E-plane cut topology. The S-parameters of the filter are measured and compared with the simulations. The measured passband insertion loss is approximately 0.4 dB worse than in the simulation, and the measured passband width is approximately 3.4% narrower. The measured filter attenuation roll-off corresponds well to the simulation. We also compare our S-parameter measurements of the E-plane filter with corresponding measurements of a very similar H-plane filter. The transmission and reflection characteristics of the E-plane filter are better than those of the H-plane filter.
