Michel Ney

Integration of optimized low-pass filters in a bandpass filter for out-of-band improvement

We propose an original structure for the design of high performance filters with simultaneously controlled band-pass and band-reject responses. The band-reject response is controlled due to the integration of low-pass structure. Thus, the spurious resonances of the band-pass filter are rejected up to the low-pass filter ones. In this way, we have to optimize the response of the low-pass structure in order to control the out-of-band response of the band-pass filters.

Integration of optimized low-pass filters in band-pass filters for out-of-band improvement

We propose an original structure for the design of high performance filters with simultaneously controlled band-pass and band-reject responses. The band-reject response is controlled due to the integration of low-pass structure. Thus, the spurious resonances of the band-pass filter are rejected up to the low-pass filter ones. In this way, we have to optimize the response of the low-pass structure in order to control the out-of-band response of the band-pass filters.

The Method of Weighted Residuals: A General Approach to Deriving Time- and Frequency-Domain Numerical Methods

The method of the weighted residuals (MWR), sometimes known as the method of moments (MoM), has traditionally been applied in the frequency domain and has been shown to be effective and efficient, especially in computing open electromagnetic structure problems. Although it has been extended to the time domain in various forms, it is generally employed to solve integral formulations derived from Maxwells equations. Therefore, it is often considered to be one type of numerical method that is different from other numerical methods, such as finite-difference methods. However, in this paper we will show that the MWR, or MoM, is not just a method per se: it can in fact be a general framework for or approach to unifying or deriving most of the numerical methods developed so far, either in the frequency domain or in the time domain. As a result, all numerical methods can be quite easily understood and can be categorized in one general method, although their conventional derivations may still have their respective advantages. One potential application is that the hybridization of different numerical methods can now be done within a uniform framework. The paper is intended for both beginners and experienced practitioners in the area of numerical electromagnetic modeling.

Radio-over-Fibre access for sustainable Digital Cities

Pervasive broadband access will transform cities to the net social, environmental and economic benefit of the e-City dweller as did the introduction of utility and transport network infrastructures. Yet without action, the quantity of greenhouse gas emissions attributable to the increasing energy consumption of access networks will become a serious threat to the environment. This paper introduces the vision of a ‘sustainable Digital City’ and then considers strategies to overcome economic and technical hurdles faced by engineers responsible for developing the information and communications technology (ICT) network infrastructure of a Digital City. In particular, ICT energy consumption, already an issue from an operating cost perspective, is responsible for 3 % of global energy consumption and is growing unsustainably. A grand challenge is to conceive of networks, systems and devices that together can cap wireless network energy consumption whilst accommodating growth in the number of subscribers and the bandwidth of services. This paper provides some first research directions to tackle this grand challenge. A distributed antenna system with radio frequency (RF) transport over an optical fibre (or optical wireless in benign environments) distribution network is identified as best suited to wireless access in cluttered urban environments expected in a Digital City from an energy consumption perspective. This is a similar architecture to Radio-over-Fibre which, for decades, has been synonymous with RF transport over analogue intensity-modulated direct detection optical links. However, it is suggested herein that digital coherent optical transport of RF holds greater promise than the orthodox approach. The composition of the wireless and optical channels is then linear, which eases the digital signal processing tasks and permits robust wireless protocols to be used end-to-end natively which offers gains in terms of capacity and energy efficiency. The arguments are supported by simulation studies of distributed antenna systems and digital coherent Radio-over-Fibre links.

RADIATION FROM SURFACE WITH PERIODIC BOUNDARY OF METAMATERIALS EXCITED BY A CURRENT

The rigorous modeling and analysis of electromagnetic wave transformation and radiation from the periodic boundary of metamaterial are presented. The nature of the phenomenon of resonant radiation and the influence of various parameters on it are investigated. The study is carried out with the objective of potential applications to antenna design. Simulated results show that very high directivity can be obtained and that beam steering can be achieved by adjusting proper parameters.

TLM Extension to Electromagnetic Field Analysis of Anisotropic and Dispersive Media: A Unified Field Equation

The transmission-line matrix (TLM) method, in time domain, is extended to account for the presence of anisotropic and dispersive media in electromagnetic structures or devices. The model is thoroughly constructed by using Maxwells equations that make it a unified general TLM formulation. Numerical results are compared with experimental measurements; hence, in the case of ferrite-based structures, validating the model and showing the accuracy of the approach.

Comparison of Radiation Modeling Techniques Up to 10 GHz—Application on a Microstrip PCB Trace

This paper presents a comparative study on the electromagnetic emissions modeling of a microstrip signal trace. Different modeling techniques based on transmission-line theory, simulation program with integrated circuits emphasis circuit analysis and electromagnetic topology are investigated to predict the radiated emissions up to 10 GHz. All of them use different simplifications to calculate the trace current distribution and the radiated emissions. For both matched and mismatched cases, the radiation frequency response for a fixed direction in the far-field region is calculated with an analytical method, a circuit method and a modified Krons method for electromagnetic compatibility. Then, results are compared with a full-wave simulation and good agreement is found over a wide frequency range.

DOE Based Design Method For Coupled-Lines Narrow Bandpass Filter Response Improvement.

In this paper we discuss about various modifications of classical coupled-lines narrow bandpass filter to obtain some frequency response improvement. The first modification concerns the broadening of the resonator strip-widths to improve their unloaded Q-factor. The second modification consists in replacing the in/out coupled lines section by tapped lines feeding. Finally a transmission zero is added using a geometrical modification that favor coupling between non-adjacent resonators. The theoretical investigation is carried out through a DOE based sensitivity study using both a circuit modeling approach and a full wave analysis. Theoretical and experimental results on microstrip filters are compared.

Matched absorbing medium techniques for full-wave TLM simulation of microwave and millimeter-wave components

This paper investigates the absorbing layer techniques for three-dimensional transmission-line matrix (3d-tlm) simulations. Applications are the full-wave analysis of structures such as microwave and millimeter-wave circuits open to free space. Two approaches are presented, namely the matched layer (ml) and the perfectly matched layer (pml) technique which is used for general cases. For the ml technique, which is efficient for matching guides operating in a quasi-TEM condition, a comparison of the different tlm condensed node is carried out. Concerning the more general case of the pml technique, the theoretical development of a new general three-dimensional (3d) tlm condensed cell is presented. Results pertaining to the characterization of planar circuits are compared with other solutions or measurements. It is found that a proposed unified approach, which includes the tlm simulation for matched layer media, yields very good performance in terms of the absorbing boundary condition (abc).RésuméCet article présente des techniques des milieux absorbants pour la modelisation par la methode de la matrice des lignes de transmission tridimensionnelle (3d-tlm). Les applications sont l’analyse électromagnétique de circuits microondes et millimétriques ouverts sur l’espace libre. Les deux approches discutées utilisent les milieux adaptés (ml) et les couches parfaitement adaptées (pml), ces dernières étant utilisées pour le cas général. La technique ml, qui est efficace pour l’adaptation de guides opérant en modes quasi statiques, est étudiée dans le cas de différents types de cellules tlm condensées. Pour la simulation des milieux pml applicables aux cas plus généraux, le développement théorique d’une nouvelle cellule tlm tridimensionnelle est présenté. Dans le cadre de caractérisation de discontinuités en technologic plaquée, des résultats de simulations sont comparés avec des solutions trouvées par d’autres méthodes ou la mesure. On trouve que l’approche unifiée proposée donne de très bonnes performances en termes de conditions absorbantes aux limites (abc).

Miniaturized loop-filter with high out-of-band rejection for future UMTS mobile terminals

This paper deals about the implementation of miniaturized band-pass filters operating on a very narrow bandwidth. An original synthesis technique is proposed for achieving high out-of-band rejection by means of a loop resonator where transmission zeros are introduced through mutual coupling effects. Quite good performances are obtained regarding losses, size and spurious resonances for the proposed topology, which can be considered as a good solution for mobile equipments.