A. Cassinese

Superconducting antennas for telecommunication applications based on dual mode cross slotted patches

Abstract Dual mode devices based on high temperature superconducting films represent an interesting class for telecommunication applications since they combine a miniaturized size with a good power handling. Here we report on a novel compact antenna obtained by crossing a square patch with two or more slots. The proposed design has an antenna size reduction of about 40% as compared to the conventional square patch microstrip antennas. Single patch antenna both with linear (LP) and circular (CP) polarization operating in the X-band have been designed and tested at prototype level. They are realized by using double sided (YBa2Cu3O7−x) YBCO and Tl2Ba2Ca1Cu2O8 (Tl-2212) superconducting films grown on MgO substrates and tested with a portable cryocooler. They showed at T=77 K a return loss

A metal-organic chemical vapor deposition approach to double-sided Tl2Ba2Ca1Cu2O8 superconducting films on LaAlO3(100) substrates

Double-sided Tl2Ba2CaCu2O8 (Tl-2212) films for device applications have been fabricated through thallium vapor diffusion into BaCaCuOF matrices deposited by a novel metal-organic chemical vapor deposition (MOCVD) process onto 10 × 10 mm2 LaAlO3 (100) substrates. The present approach uses a multimetal molten single source in a monocomponent hot-wall MOCVD reactor whose geometry allows simultaneous and uniform film growth on both sides of the substrate. Both sides are epitaxially coated by homogeneous and monophasic Tl-2212 films, which, even more importantly, have comparable superconducting and transport properties.

Dual mode cross slotted filter realized with double-sided Tl2Ba2CaCu2O8 films grown by MOCVD

We report on the realization of dual mode microwave filters based on Tl2Ba2Ca1Cu2O8 (Tl-2212) double-sided superconducting films. The Tl-2212 samples have been grown ex situ on 10×10 mm2 LaAlO3 (100) substrates by a combined approach of metal-organic chemical vapour deposition (MOCVD) and thallium vapour diffusion. Their morphological, compositional and structural natures have been investigated by scanning electron microscopy, energy dispersive x-ray analyses and x-ray diffraction characterization. Both sides of the films are smooth, homogeneous in thickness and composition and show epitaxially-grown Tl-2212 phases. Typical values of Tc = 100 K and Jc = 0.05 MA cm-2 at 77 K have been inductively measured for both sides. Microwave measurements have been performed at 20 GHz by using a dielectric resonator. Two planar superconducting single-stage dual mode filters operating in the C-band with 1% and 10% fractional bandwidth have been realized. The basic element of the device is a square patch resonator diagonally crossed by unequal slots providing both a size reduction and a simple and controllable way to couple the two degenerate modes. Device response has been studied at different temperatures, performing power and intermodulation measurements. In view of practical applications, the results are compared with those obtained by a filter based on high-quality YBCO films.

Superconducting gap anisotropy of LuNi 2 B 2 C thin films from microwave surface impedance measurements

Surface impedance measurements of

Nonlinear microwave properties of Nb3Sn sputtered superconducting films

{\mathrm{LuNi}}_{2}{\mathrm{B}}_{2}\mathrm{C}

Superconducting resonators for telecommunication application based on fractal layout

superconducting thin films as a function of temperature have been performed down to 1.5 K and at 20 GHz using a dielectric resonator technique. The magnetic penetration depth closely reproduces the standard BCS result, but with a reduced value of the energy gap at low temperature. These data provide evidence for an anisotropic s-wave character of the order parameter symmetry in

Superconducting filters based on mixed resonators

{\mathrm{LuNi}}_{2}{\mathrm{B}}_{2}\mathrm{C}.

Study of the microwave electrodynamic response of MgB2 thin films

From the evaluation of the real part of complex conductivity, we have observed constructive (type II) coherence effects in the electromagnetic absorption below

Superconducting properties of YNdBaCuO and NdBaCuO thin films deposited by dc sputtering

{T}_{c}.