arXiv subjects

Christophe Caloz

Publications and source records attributed to Christophe Caloz.

131 records · Page 8Linked to original sources

arXiv2014

Generalized Coupled-line All-Pass Phasers

Generalized coupled-line all-pass phasers, based on transversally-cascaded (TC), longitudinally-cascaded (LC) and hybrid-cascaded (HC) coupled transmission line sections, are presented and demonstrated using analytical, full-wave and experimental results. It is shown that for N commensurate coupled-line sections, LC and TC phasers exhibit N group delay peaks per coupled-line section harmonic frequency band, in contrast to the TC configuration, which exhibits only one peak within this band. It is also shown that for a given maximum achievable coupling-coefficient, the HC configuration provides the largest group delay swing. A wave-interference analysis is finally applied to the various coupled-line phasers, explaining their unique group delay characteristics based on physical wave-propagation mechanisms.

physics.optics↗

arXiv2014

Unveiling Magnetic Dipole Radiation in Phase-Reversal Leaky-Wave Antennas

The radiation principle of travelling-wave type phase-reversal antennas is explained in details, unveiling the presence of magnetic-dipole radiation in addition to well-known electric dipole radiation. It is point out that such magnetic dipole radiation is specific to the case of traveling-wave phase-reversal antennas whereas only electric-dipole radiation exists in resonant-type phase-reversal antennas. It is shown that a phase-reversal travelling-wave antenna alternately operates as an array of magnetic dipoles and an array of electric-dipoles during a time-harmonic period. This radiation mechanism is confirmed through both full-wave and experimental results.

physics.class-ph↗

arXiv2013

Design of Dispersive Delay Structures (DDSs) Formed by Coupled C-Sections Using Predistortion with Space Mapping

The concept of space mapping is applied, for the first time, to the design of microwave dispersive delay structures (DDSs). DDSs are components providing specified group delay versus frequency responses for real-time radio systems. The DDSs considered in this paper are formed by cascaded coupled C-sections. It is first shown that aggressive space mapping does not provide sufficient accuracy in the synthesis of DDSs. To address this issue, we propose a predistortion space mapping technique. Compared to aggressive space mapping, this technique provides enhanced accuracy, while compared to output space mapping, it provides greater implementation simplicity. Two full-wave and one experimental examples are provided to illustrate the proposed predistortion space mapping technique.

physics.optics↗

arXiv2013

Analog Signal Processing

Analog signal processing (ASP) is presented as a systematic approach to address future challenges in high speed and high frequency microwave applications. The general concept of ASP is explained with the help of examples emphasizing basic ASP effects, such as time spreading and compression, chirping and frequency discrimination. Phasers, which represent the core of ASP systems, are explained to be elements exhibiting a frequency-dependent group delay response, and hence a nonlinear phase response versus frequency, and various phaser technologies are discussed and compared. Real-time Fourier transformation (RTFT) is derived as one of the most fundamental ASP operations. Upon this basis, the specifications of a phaser resolution, absolute bandwidth and magnitude balance are established, and techniques are proposed to enhance phasers for higher ASP performance. Novel closed-form synthesis techniques, applicable to all-pass transmission-type cascaded Csection phasers, all-pass reflection-type coupled resonator phasers and band-pass cross-coupled resonator phasers are described. Several applications using these phasers are presented, including a tunable pulse delay system, a spectrum sniffer and a realtime spectrum analyzer (RTSA). Finally, future challenges and opportunities are discussed.

physics.optics↗

arXiv2013

Terahertz Magnetoplasmon Energy Concentration and Splitting in Graphene PN Junctions

Terahertz plasmons and magnetoplasmons propagating along electrically and chemically doped graphene p-n junctions are investigated. It is shown that such junctions support non-reciprocal magnetoplasmonic modes which get concentrated at the middle of the junction in one direction and split away from the middle of the junction in the other direction under the application of an external static magnetic field. This phenomenon follows from the combined effects of circular birefringence and carrier density non-uniformity. It can be exploited for the realization of plasmonic isolators.

physics.optics↗