Superconducting NbC nanoparticles synthesized by laser ablation in a liquid.

Niobium carbide (NbC) is a high-field type II superconductor with a critical temperature () of 11.1 K, slightly exceeding that of pure Nb ( = 9 K). The reduction of NbC to the nanoparticle scale leads to significant changes in its critical field and/or the superconducting temperature.

Q-band 4-state phase shifter in planar technology: Circuit design and performance analysis.

A 30% bandwidth phase shifter with four phase states is designed to be integrated in a radio astronomy receiver. The circuit has two 90° out-of-phase microwave phase-shifting branches which are combined by Wilkinson power dividers. Each branch is composed of a 180° phase shifter and a band-pass filter.

The Thirty Gigahertz Instrument Receiver for the QUIJOTE Experiment: Preliminary Polarization Measurements and Systematic-Error Analysis.

This paper presents preliminary polarization measurements and systematic-error characterization of the Thirty Gigahertz Instrument receiver developed for the QUIJOTE experiment. The instrument has been designed to measure the polarization of Cosmic Microwave Background radiation from the sky, obtaining the Q, U, and I Stokes parameters of the incoming signal simultaneously. Two kinds of linearly polarized input signals have been used as excitations in the polarimeter measurement tests in the laboratory; these show consistent results in terms of the Stokes parameters obtained.

The thirty gigahertz instrument receiver for the Q-U-I Joint Tenerife experiment: concept and experimental results.

This paper presents the analysis, design, and characterization of the thirty gigahertz instrument receiver developed for the Q-U-I Joint Tenerife experiment. The receiver is aimed to obtain polarization data of the cosmic microwave background radiation from the sky, obtaining the Q, U, and I Stokes parameters of the incoming signal simultaneously. A comprehensive analysis of the theory behind the proposed receiver is presented for a linearly polarized input signal, and the functionality tests have demonstrated adequate results in terms of Stokes parameters, which validate the concept of the receiver based on electronic phase switching.

Design methodology and performance analysis of a wideband 90° phase switch for radiometer applications.

This paper presents the analysis, design, and characterization of a wideband 90° phase switch in Ka-band. The phase switch is based on two microstrip bandpass filters in which the commutation is performed by a novel single-pole double-throw (SPDT) switch. The analysis of π-network bandpass filters is provided, obtaining the phase difference and amplitude imbalance between filters and their scattering parameters; tested results show an average phase difference of 88.