Alexandre Jean René Serres

Analysis of Multilayer Amplifier Structure by an Efficient Iterative Technique

A new compact microwave amplifier structure using an iterative technique based on the wave concept iterative procedure (WCIP) is presented. This new multilayer structure is composed of five planar interfaces of strip lines. The technique used to model this structure provides a mixed resolution in modal and spatial domain. By taking the best advantage of each resolution domain, a lower computing time is obtained. The purpose of this paper is to demonstrate that a near field amplification technique is achievable and the WCIP is suitable to electromagnetic analysis of this kind of structure. The numerical results show 13.4 dB gain at 5.6 GHz.

Approximation of a rectangular via hole from a cylindrical cross section using the fundamental TM mode

In this paper, is presented how to calculate the dimensions of a via hole with rectangular cross section from the dimensions of a cylindrical via hole. In the approach presented herein, it is only considered the fundamental TM mode to calculate the propagation constant. This one is determined for a frequency range from 0 to 20 GHz, for both structures. It is shown that the values of constant propagations for a cylindrical structure are different to a rectangular structure when the relationship between the dimensions of the waveguide and the via hole is lower than 200.

Bio-inspired antenna for UWB systems

In this paper is presented a new printed monopole antenna, bio-inspired by jasmine flower, that meets the Federal Communications Commission parameters for ultra-wideband systems. The design of the printed monopole antenna in jasmine flower has developed from a printed monopole antenna with circular geometry, with comparison results. The measured results of bio-inspired antenna in the jasmine flower showed compatibility with the parameters required by the FCC for ultra-wideband technology. It obtained bandwidth of 9.75 GHz, half-power beamwidth of 148 degrees, omnidirectional radiation pattern, gain of 5.99 dBi, power spectral density below -41.3 dBm across the bandwidth of ultra-wideband technology, small pulse distortion, and constant group delay, with variations of less than 2ns.

Implementation of beam-steering front-ends at 2.45 GHz using modified Wilkinson power dividers, reflexion type phase shifters and C-shape monopole antennas: First results

The aim of this work is to implement electronic beam-steering systems. More specifically, we propose systems working at 2.45 GHz. For that, power dividers (PD), phase shifters (RTPS), and printed antennas are used. The main advantage of electronic beam-steering systems is related to the simple realization and low cost, when compared with mechanical ones. For some devices, a small shift in frequency is observed from 2.45 to 2.40 GHz. At 2.40 GHz, PD and RTPS show very low losses: 0.10 dB for the PD and between 0.55 and 1.40 dB for the RTPS; as well as good return losses (-30.19 dB and -2.85 dB, respectively). The RTPS enables to perform 360° of phase-shift with a 0.5-2.72 pF varactor. With the proposed topologies, a simulated 2-antenna array beam-steering of ±85° has been shown with return loss of -12.88 dB. Since inclination angle F also varied, no relevant measured results were obtained in the available anechoic chamber, which works only in the Φ = 0 plane. A 4-antenna array was then measured. Results reach gains up to 5.58 dBi with -11.07 dB of return losses at 2.40 GHz. Since this is still a preliminary work, the results presented are very promising.

Determination of the electromagnetic wave polarization from unknown sources by the method of linear component modified

In this paper, we propose a modification of the linear component technique for identification of the electromagnetic waves polarization. The proposed measurement is divided in two setups and is used to obtain the amplitude of the two accessible electric field components of a plane wave. From the axial ratio and the discrete phase information obtained by trial, it is possible to determine the amplitude and phase of the electric field radiated by one or more sources. The setup is constituted by a pair of dipoles orthogonally positioned to determine these two field components. The results are obtained for two kinds of polarization: linear and circular. Good agreement was obtained between the simulated and measured results.

Dual-Band Frequency Selective Surface with Angular Stability for WLAN Applications

A double ring FSS with angular stability operating in the WLAN range is discussed in this paper. The Euclidean geometry of the proposed FSS is composed of a periodic array of metallic patches on a dielectric layer of FR4, which is designed and simulated using the commercial software ANSYS. Measurements and simulation of the proposed structure are compared to single ring FSS. An investigation of angular stability was performed in the WLAN range. The double ring FSS presents good response between simulated and measured results, in the 2.40 GHz band, the FSS presented angular stability from 0° to 40°, and for 5.30 GHz, the angular stability was observed from 0° to 20°.

Aperture-coupled on-chip patch antennas for ISM band 60 GHz

This paper presents the development of aperture-coupled patch antennas operating in industrial scientific and medical band at 60 GHz (57 GHZ to 64 GHz), with square and circular shapes, for on-chip application. The aperture-coupled antenna proposed is composed by a transmission feed line, an aperture and patch element built in aluminum with 10 micrometers of thickness lying on two layers of silicon with height of 200 micrometers. Dimensions of the square and circular antennas were calculated according to the effective wavelength for resonance frequency at 60 GHz in order to match at 50 Ohms. The proposed antennas have been simulated using the commercial software ANSYS. Both antennas show omnidirectional radiation pattern, with half power beamwidth greater than 149 degrees. Square patch presented a more compact structure, with dimension less than 1.55 mm, return loss of −55 dB, and bandwidth of 3.98 GHz, however the circular antenna, with a greater metallic area, achieved a better gain of 5.88 dBi.

Modified Wilkinson Power Divider and dipole antenna for beamforming systems at 5.8 GHz

Beamforming front-ends are an attractive technology because it concentrates its radiated power in one direction, which can improve energy efficiency and reduce undesirable interference. In this context, electronic beamforming systems have lower cost than mechanical ones. Knowing the uses of directive antennas and power dividers in electronic beamforming systems, this work aims at the design, simulation and measurements of these components at 5.8 GHz. Measurements with Power Divider showed very good return and insertion losses at 5.8 GHz: S11 = -23.5 dB and S21 = -3.8 dB. A printed dipole antenna was then fabricated, presenting -14.6 dB of return losses and a 2.82 dBi gain. Later, a 2-antenna beamforming front-end was implemented, proving the beamforming capability with the proposed devices. It also presented S11 = -15.7 dB, and a high directive gain (10.3 dBi). Since this is still a preliminary work, the results presented are very promising.

Modal analysis of a metallic via hole by the WCIP

This paper presents a new electromagnetic modeling of a via-hole using a Wave Concept Iterative Procedure. There are specific TM modes associated with the insertion of the via-hole influencing the incident and reflected waves, called the “vias modes”. The formulation and results are presented considering the influence of one and two vias mode. The advantage of the model presented is the possibility to simulate planar circuits with a layer and a via-hole considering the effects of the field that propagates around the via.

Influence of conductor tube in circular PMA for UWB range

The study of printed monopole antennas (PMA) with truncated ground plane has application in various types of technologies. This kind of ground plane, promotes an omnidirectional radiation pattern with broadband response and allows the antenna to suffer influence from nearby conductive material. This article presents the simulated and measured results of influences from a rectangular aluminum tube on a circular PMA that meets the UWB technology requirements. The results obtained indicate that the tube at a wavelength distance of 1/8? reduce the bandwidth by 50% in X-band (8 ~ 12 GHz), half power bandwidth HPBW is approximately 90° and gain of 6.92 dBi.