Miniaturized and Reconfigurable Notch Antennas Using a BST Thin Film Varactor

International audienceFerroelectric (FE) thin film varactor technology can be used for antenna miniaturization and reconfiguration. We present more particularly a quarter wavelength notch antenna with a Barium Strontium Titanate (Ba(1-x)SrxTiO3, BST) thin film in MIM geometry. Integration of the BST varactor yields a size reduction of approximately 56% with respect to the initial antenna size (0.064 0 without BST layer) and the miniaturized antenna is tunable from 0.94 GHz to 1.07 GHz

Miniaturized and Reconfigurable Notch Antennas Using a BST Thin Film Varactor

International audienceFerroelectric (FE) thin film varactor technology can be used for antenna miniaturization and reconfiguration. We present more particularly a quarter wavelength notch antenna with a Barium Strontium Titanate (Ba(1-x)SrxTiO3, BST) thin film in MIM geometry. Integration of the BST varactor yields a size reduction of approximately 56% with respect to the initial antenna size (0.064 0 without BST layer) and the miniaturized antenna is tunable from 0.94 GHz to 1.07 GHz

Study of process intensification Higee technology applied to the absorption

Treballs Finals de Grau d'Enginyeria Química, Facultat de Química, Universitat de Barcelona, Curs: 2015-2016, Tutor: Jose Maria Gutiérrez GonzálezHigee technology or High-gravity Technology has been widely studied for the intensification of industrial processes such as absorption, desorption, distillation, extraction, among others, in order to find and improve the benefits compared to conventional methods. According to Documents about Best Available Techniques (BREFs), Higee technology is emerging as an alternative to the methods used so far. This work studies Higee technology improvements applied to the absorption process compared to conventional packed columns. The absorption is mainly used to remove pollutant components of a gas stream to avoid leaks outside and/or to recover some component that the stream could contain for production purposes. To achieve the goals of this project, a bibliographic search of Higee technology, studied by different authors, has been performed. In this research, the focus is on the modifications made in recent years in order to show the advantages of this technology compared to the conventional one. After this research, the design of a conventional absorption column and Rotating Packed Bed have been studied in order to make a comparison among the design results and a comparison of these with those obtained experimentally by the different authors. From these studies the main conclusion is that the use of Higee technology get a huge reduction in the volume of the device and it is also possible to use smaller amounts of absorbent liquid. However, Higee technology presents some disadvantages over conventional technology because it is necessary that the absorbent liquid be subjected to a centrifugal force, so this will require greater energy. All these changes make the design more complex and the device suffers a faster wear due to continuous movement and, consequently, it increases the economic cost. Thus, based on studies performed so far, replacing the conventional absorption column for Higee technology is not recommendable. However, it should be further investigated because it has potential to get better results in comparison with conventional processes, either applied in the process studied in this work or applied to another types of processes

Ferroelectric tunability: from characterization to telecomunication application

4International audienceAdvanced dielectric spectroscopy enables studying of the ferroelectric complex permittivity. Interpretation with the hyperbolic law provides a better fundamental understanding of the material's tunability: bulk contribution, domain wall vibration and displacements may be discerned. Applications, like mobile telecommunication terminals may profit for the design of miniaturized and tunable antennas. As an example, conception and realization of a notch slot antenna with an integrated ferroelectric thin film varactor is presented

Study of ferroelectric/dielectric multilayers for tunable stub resonator applications at microwaves

International audienceTunable coplanar waveguide stub resonators deposited on various ferroelectric/dielectric heterostructures are studied in the 10-GHz band. A frequency tunability of up to ~ 45% is achieved under a moderate biasing field (Ebias < 100 kV/cm) when the resonator is printed on KTa0.5Nb0.5O3 (KTN) ferroelectric thin film alone: this comes from the large permittivity agility of the KTN material (εr(KTN) varies from ~ 700 to ~ 200). Nevertheless this also leads to significant insertion loss due to the dielectric loss of the ferroelectric material itself (tanδr(KTN) ≈ 0.15-0.30 at 10 GHz). In this paper, an original route has been considered to reduce the device loss while keeping up a high frequency tunability. It consists in associating the KTN film with a dielectric film to elaborate ferroelectric/dielectric multilayers. The Bi1.5Zn0.9Nb1.5O7−δ (BZN) oxide material is selected here for two main reasons, namely its low dielectric loss (tanδr(BZN) ≈ 0.005-0.0075) and its moderate relative permittivity (εr(BZN) ≈ 95-125) at 12.5 GHz. The relevance of this approach is studied numerically and experimentally. We compare numerically two different heterostructures for which the ferroelectric film is grown on the dielectric film (KTN/BZN), or vice versa (BZN/KTN). A stub resonator printed on the most relevant heterostructure has been fabricated, and experimental data are discussed and compared to the numerical results

Loss reduction technique in ferroelectric tunable devices by laser micro-etching. Application to a CPW stub resonator in X-band

International audienceFerroelectric materials are known to be lossy at microwaves. A local microetching technique based on laser ablation is implemented here to reduce the insertion loss of highly tunable devices fabricated on KTa1-xNbxO3 (KTN) ferroelectric thin films. The relevance of this approach is studied in X-band by comparing numerically and experimentally the performance of a frequency-tunable coplanar waveguide stub resonator before and after KTN microetching. The experimental data demonstrate a large loss reduction (by a factor 3.3), while keeping a high-frequency tunability (47%) under a moderate biasing static electric field (80 kV/cm). This approach paves the way for the design of ferroelectric reconfigurable devices with attractive performance in X-band and even beyond

Cистемна організація уваги та загальні принципи її корекції як засіб оптимізації учбової та професійної діяльності

У статті викладено результати літературних та експериментальних досліджень, у яких розкриваються основні напрямки, котрі стосуються феномени уваги:механізми її виникнення, типи уваги, функції контролю та управління. Розглянуто ряд методів, котрі можуть бути використані для тренінгів, з метою збільшення об’єму уваги, ступеня її концентрації, швидкості, ступеня зосередження, переключення і розподілу

Matériau ITO en couche mince : Interaction avec le rayonnement UV et applications…

Séminair

Interest of ultrashort laser pulse for PLD

International audienc

Dielectric thin film characterization using MIM capacitor and application in antennas miniaturization

International audienc