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Eutectic temperature and composition in the CuO-Ti0 2 pseudobinary system have been experimentally determined in air by means differential thermal analysis (DTA), thermogravimetry (TG) and hot-stage microscopy (HSM). Samples of the new eutectic composition treated at different temperatures have been characterized by X-ray diffraction (XRD) and X-ray absorption near-edge structural spectroscopy (XANES) to identify phases and to determine the Cu valence state, respectively. The results show that the eutectic temperature in air is higher by 100 °C (~1000 °C) for a Ti-richer composition (X Ti02 = 25 mol%) than the one calculated in the literature. The reduction of Cu 2+ to Cu + takes places at about 1030 °C. The existence of Cu 2 Ti0 3 and Cu 3 Ti0 4 has been confirmed by XRD in the temperature range between 1045 and 1200 °C.

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Fe3+‐ or Nb5+‐doped CaCu3Ti4O12 (CCTO) ceramics show higher values of both room‐temperature (RT) grain conductivity and dielectric constant than undoped ceramics. Microstructural and structural characterization combined with magnetic properties reveal the coexistence of two components that seem relevant for the dielectric behavior of the material. The grain possesses a nanostructure characterized by layered domains with thicknesses <80 nm. The formation of the layered domains is associated with the evidence of different chemical states as Cu2+/Cu+ and Ti4+/Ti3+ that are present in the material. The magnetic contribution is related to two coupled effects: the antiferromagnetic (AFM) response with TN=25 K ascribed to Cu2+, and a paramagnetic‐like contribution attributed to Ti3+ cations. The coexistence of two coupled magnetic contributions could explain the proposed unusual coupling of the AFM Cu2+ superexchange interaction through the nonmagnetic Ti4+ rather than via the usual oxygen coupling. The lower the paramagnetic‐like contribution at RT, the larger the conductivity and the dielectric constant of the material are. Below 150 K, the increase of the paramagnetic‐like contribution is correlated with the low transition temperature of the CCTO.

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A compact polarizer based on a corrugated waveguide of square cross-section including the input and output transitions is analysed by means of an accurate and efficientfullwave software based on Mode Matching, and a dual-frequency bandpolarizer of high electrical performance in the Ku band has been "fully" designed. The good agreement between the numerical and experimental results confirms both the design process and the proposed polarizer which can easily include different cross-sections of the attached Orthomode Transducer (OMT) and horn devices, thus resulting in a very compact antenna.