Wet chemical etching of (Ba1-xSrx)TiO3 (BST) thin films has been investigated. The etchant was prepared from buffered hydrofluoric acid (BHF) and nitric acid (HNO3), BHF being the reactive agent while HNO3 acts as a catalyst. X-ray diffraction and energy dispersive X-ray spectrometry were performed in order to qualitatively and quantitatively follow the etching process. Scanning electron microscopy and a profilometer were used for determining the etching quality. The ferroelectric thin films were elaborated by a modified sol-gel process and by spin-coating on insulating (Si-wafers) or metal (stainless steel) substrates. Classic photolithography technique and a positive photo resist were used for the transfer of the patterns. Appropriate water dilution reduces the etching speed, thus allowing a better visual control of the process.

International audienceIn this paper, we introduce the dielectric characterization of soft polymer, polyurethane (PU), between 1 and 31 GHz frequency band using Grounded CoPlanar Waveguide (GCPW) lines with a modified analytical method. The unavoidable thin metallization (1 μm) of GCPW lines on polyurethane yields high conductor losses, which contribute to the extracted global losses up to 58% at 4 GHz. In order to get more precisely the dielectric losses, a modification of an already existing analytical model by coupling it with 3D electromagnetic simulations is proposed, which allows to estimate and subtract quickly the conductor losses. The measurements indicated that polyurethane relative permittivity ranges from 3.49 to 2.65 and the loss tangent was about 0.08, which is in agreement with the state of the art on this grade of PU as well as the Metal-Insulator-Metal capacitors characterizations (from 10−1 to 107 Hz and from 2 × 108 to 5 × 109 Hz). The proposed approach may open a fast and simple way for precisely determining the microwave dielectric properties of (ultra) soft polymers in a large bandwidth

In this paper, we present the original use of a recyclable and low cost soft polymer, polyurethane (PU) (ε r ≈ 3.5 at 10 GHz), as part of a dielectric substrate of a microstrip patch antenna. The combination of simple membrane manufacturing process and the low Young's modulus of PU (E PU ≈ 30 MPa) are employed in an X-band antenna application in this study. The PU dielectric characterizations indicate the high loss tangent value (tan δ ≈ 0.1 at 10 GHz). Membrane supported technology is used to reduce the influence of this high loss and increase the antenna efficiency. The measurement of antenna performances such as efficiency (η ≈ 31.7%) confirms the viability of the technological process and the specific patch antenna design developed in this work. Besides, the potential of the PU-based soft patch antenna for frequency agility (3.88%) via mechanical reconfiguration is also shown.

This paper investigates the provenance of the northern sector of the Jenkinson map of Russia printed by Ortelius in 1570. Scholarly opinion has been notably discordant on its authorship and its relationship to a chart drawn by William Borough of the northern coasts of Russia, whose date has also been disputed. An examination of literary sources, Borough's biography, and the map and chart leads to these conclusions: the northern sector of the map surely was drawn by Borough, it is closely related to Borough's chart, and – contrary to the datings others have assigned the chart – it must have been sketched in 1567– 68.

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