Blaise Ravelo

Bio: Blaise Ravelo is an academic researcher from Nanjing University of Information Science and Technology. The author has contributed to research in topics: Group delay and phase delay & Microstrip. The author has an hindex of 21, co-authored 196 publications receiving 1727 citations. Previous affiliations of Blaise Ravelo include École Supérieure d'Ingénieurs en Génie Électrique & Nanjing University.

Characterization of the Regular Polygonal Waveguide for the RF EM Shielding Application

Abstract: This article presents a theoretical characterization of the regular polygonal waveguide (RPW) having n-sides. Based on the symmetrical circular symmetry of the RPW and the circular waveguide (CW), the analogy between the electromagnetic (EM) behaviors of these to waveguide (WG) is established. After a brief recall about the state of the art concerning the WG engineering and its application, we introduce a basic theory of the WG presenting a regular polygonal cross-section with n-sides. By considering, the fundamental mode TE11, we develop the main mathematical formulas summarizing the difierent characteristics (cut-ofi frequency, fc, propagating constant, k11 and S-parameters) appropriated to any RPW in function of its physical parameters (number of sides, n, diameter, D and height, h). In order to verify the validation of the developed analytical expressions, comparisons between the HFSS simulated and theoretical dispersion diagrams of regular pentagonal (n = 5), hexagonal (n = 6), heptagonal (n = 5) metallic (copper) WG with for example, 50mm outer diameter are presented. So, it was demonstrated that very good correlation between the theoretical predictions (fc(n), k11(n)) is found with a relative error less than 1%. As application of the present study in terms of EM wave shielding, simulation of metallic wall with hexagonal aperture is also performed. Finally, discussion about the future work is drawn in conclusion.

Synthesis of n-way active topology for wide-band RF/microwave applications

Abstract: A novel architecture of n-way active topology for RF/microwave module applications is developed. This architecture is based on the use of active cell composed of a field effect transistor (FET) in cascade with shunt resistor. A theoretic analysis illustrating the S-parameters calculation was established. The expressions of the n-way power divider output gains were demonstrated. A synthesis method of active power-splitter or/and 180° balun in function of the considered FET stage number constituting each outer branch was proposed. A simple active power-splitter was designed using an even number of FET between the input–output branches. In addition, a variable gain active power-splitter was simulated. The FETs are biased at Vds = 6 V and Ids = 25 mA. So, insertion losses above −1.5 dB, return losses better than −15 dB and excellent isolation below −30 dB at all three ports were obtained from 0.5 to 5.5 GHz. Using odd number of FET stage, an active balun was realised. Then, simulations of active balun showi...

Computational method of extraction of the 3D E-field from the 2D H-near-field using PWS transform

Abstract: The paper introduces a computational method of 3D electric field extraction (E-field) from the 2D magnetic field components H x and H y measured in near zone. The method is based on the exploitation of the Maxwell-Ampere relation combined with the plane wave spectrum (PWS) approach. The proposed technique is validated on the example of an electromagnetic (EM) field radiated by a set of magnetic dipoles placed in the horizontal plane, as used in some modeling approaches of radiated EMC emissions. The proposed technique is therefore useful in EMC applications, simplifying the measurement process.

Design and synthesis of flexible switching 1 × 2 antenna array on Kapton substrate

Abstract: Flexible front- and back-end RF/analogue system antennas were recently emerged. However, little flexible antenna system design is available so far, in planar hybrid technology with surface mounted components. This paper describes the design feasibility of flexible switching 1 × 2 antenna array system. It acts as a switching antenna implemented in hexapole configuration. The system is comprised of a key element RF switch terminated by two identical patch antennas associated to half-wave elementary transmission lines (TLs). A detailed theory illustrating the global S-parameter model determination in function of the given RF-switch return and insertion losses is established. In difference to the conventional microwave circuit theory, the proposed equivalent S-parameter model is originally built with the non-standard optimized antenna load. Thus, the synthesis method of the terminal antenna input impedance and the output access line characteristic impedance is formulated in function of the specified return and optimal transmission losses. The design method and theoretical approach feasibility is verified with the demonstrator of flexible switching 1 × 2 antenna array printed on Kapton substrate. The circuit prototype is implemented in hybrid planar technology integrating patch antenna operating at about 6 GHz and a packaged GaAs RF switch associated to the RF/DC signal decoupling accessory mounted surface components. Simulations of the designed circuit transmission and isolation losses from 5.5 GHz to 7 GHz were carried out by using the commercial RF switch S-parameter touchstone model provided by the manufacturer. The simulated and measured return losses are compared and discussed. Then, the measured radiation patterns confirm the proposed switched antenna concept feasibility.

Equalization of digital/mixed-signal disturbances with an negative group delay circuit

Abstract: This paper is aimed at the application of equalization technique using negative group delay (NGD) circuit for correcting mixed signals disturbed by unintentional electromagnetic effects. The basic principle illustrating the mechanism of the technique understudy and also the meaning of the intriguing NGD function is explained in details. For the feasibility illustration, an annihilation of RC-perturbations with RC-NGD-RC cascade configuration is performed. To confirm the proposed technique reliability, the feasibility of the distorted signals recovery is demonstrated with frequency- and time-domain simulations with NGD circuit sensitivity analysis deeming 10% passive elements relative tolerance. A reduction of rise-/fall-time and propagation delay of about 87 % is performed by using a trapezoidal signal represented by arbitrary 10-bits sequence “0100110100” with 250 Mbits/s-rate. The technique is useful for the RF/digital microelectronic systems signal integrity enhancement and delay reduction.

Similarity and Dimensional Methods in Mechanics

Abstract: By L I Sedov London: Cleaver-Hume Press Ltd Pp xvi + 363 Price 105s This is really two separate books within the same pair of covers First of all Chapters 1-3, some 145 pages, are devoted to the discussion of similarity and dimensional, methods and their application to a variety of problems in mechanics and fluid mechanics

Lectures on Theoretical Physics

Abstract: Vorlesungen uber theoretische Physik Von Prof. Arnold Sommerfeld. Band 1: Mechanik. Vierte, neubearbeitete Auflage. Pp. xii + 276. 18 D. marks. Band 2: Mechanik der deformierbaren Medien. Pp. xv + 376 + 4 plates. 18 D. marks. Band 3: Elektrodynamik. Pp. xvi + 368. 18 D. marks. Band 6: Partielle Differentialgleichungen der Physik. Pp. xiii + 332. 18 D. marks. (Wiesbaden: Dieterich'sche Verlagsbuchhandlung, 1947–1949.)

Harvesting Water Drop Energy by a Sequential Contact-Electrification and Electrostatic-Induction Process

Abstract: A new prototype triboelectric nanogenerator with superhydrophobic and self-cleaning features is invented to harvest water drop energy based on a sequential contact electrification and electrostatic induction process. Because of the easy-fabrication, cost-effectiveness, and robust properties, the developed triboelectric nanogenerator expands the potential applications to harvesting energy from household wastewater and raindrops.