J. Citerne

A new global time-domain electromagnetic simulator of microwave circuits including lumped elements based on finite-element method

This paper proposes an extension of the Finite Element Time Domain (FETD) method for the global electromagnetic (EM) analysis of complex inhomogeneous microwave distributed circuits, containing linear or non linear lumped elements. This technique combines Maxwells equations and circuit equations, using directly SPICE software. Results are given for a capacitor, a resistor as well as a Schottky diode.

Analysis of coplanar waveguide radiating end effects using the integral equation technique

An integral equation technique solved by the moment method associated with the single one-port model is used to analyze radiating end effects of coplanar waveguides (CPWs). This analysis has the advantage of being performed in the space domain, which allows the electric and magnetic field distributions in the whole space to be determined directly without the use of an inverse Fourier transform. An experimental method is given for the measurement of the reactance of a CPW short circuit end that allows its radiation resistance to be determined. It is shown that this resistance increases with frequency. Two examples of calculated results that give the electric field distribution in the two slots are given. The first one represents a CPW mode (odd mode), while the second represent an even coupled slots mode. The normalized reactance obtained by the present theory is compared with previously obtained measurements. The comparison shows a very good agreement. The results of a comparative study of the short-end equivalent impedance for a slotline and a CPW having the same slot width operating once in the odd mode (coplanar mode) and another time in the even mode are given. The results clearly show that the CPW operating in the odd mode has very low radiation properties when compared with the slotline and coupled slotlines operating in the even mode. >

A new global finite element analysis of microwave circuits including lumped elements

A new fullwave global analysis of complex inhomogeneous structures including passive or active, linear or non linear lumped elements is presented. Only one electromagnetic simulation of the distributed part, by a 3D finite element method using edge elements, is needed corresponding to the insertion of several lumped elements placed at the same position. Results for a resistor, a diode inserted in a microstrip circuit as well as a Gunn diode amplifier are presented and comparisons with measurements are given for an active structure.

A general treatment of matched terminations using integral equations modeling and applications

This paper presents an original approach to simulate a broadband matched load in planar structures. Theoretically, the formulation appears as an additional boundary condition in the rigorous integral equations technique, and results in a partial rearrangement of the generalized impedance matrix in the moment method resolution. Practically, it enables the whole characterization of any planar multiport discontinuity in a procedure particularly realistic in regards to experimental measurement procedures. This new refinement is demonstrated to provide a versatile and powerful tool. Some typical applications are given which illustrate its numerous capabilities. The analysis of structures as different as a shielded microstrip step and an active receiving microstrip antenna is presented and successfully compared to experiments. >

Communication systems interactive software (comsis): modeling of components and its application to the simulation of optical communication systems

comsis, which stands for communication systems interactive software, is a computer-aided-design tool based on a time approach. It allows the design, analysis, and performance optimization of optical transmission systems by use of various optical devices. comsis allows scalar or vectorial simulations, depending on whether the polarization is taken into account. An overview concerning the optical component models is given. A new model of an erbium-doped fiber amplifier allows the user to describe the amplifier through either physical or system parameters by using silicate or fluoride glass fibers or any other material, provided the user can give a file that contains the amplifiers characteristics. The new model of a single-mode fiber allows the user to describe chromatic dispersion through a constant, a function, or a file (given by the user) and to take optionally into account the Kerr and the Raman effects and the polarization-mode dispersion. The simulation tools that are used to characterize the quality of an optical transmission system are also presented. To show the systems full range of capabilities in the optical domain, we describe examples of wavelength-division-multiplexing and soliton-transmission systems.

Code division multiple access for an automotive area network over power-lines

This article presents a particular application of the spread spectrum code division multiple access concept (CDMA) based on direct spread spectrum modulation (DS-SSM) for an automotive area network on power-lines. Advantages and related problems to set up the system in a car are discussed. Measurements for the evaluation of the systems performances in terms of the additive noise and the interference caused by the other users are given. Design of this communication system is made taking also into account protection against electromagnetic disturbances.<<ETX>>

A multi-resolution MoM analysis of multiport structures using matched terminations

This paper presents the modeling of microstrip structures involving matched terminations with multi resolution 1-D method of moment (MoM). Semi-orthogonal (SO) spline wavelets are used to obtain a sparse system while a modeling of matched terminations enables a full multiport characterization. Theoretical results involving microstrip dipoles are presented and compared with experiments.

Wideband propagation measurements and Doppler analysis for the 60 GHz indoor channel

This paper presents a new wideband indoor channel sounder dedicated to the 60 GHz band. Based on the sliding correlation technique, it is optimized to perform long term measurement campaign without undersampling the fast varying impulse response. Some measurement results with Doppler analysis are presented.

Diakoptics using finite element analysis

A diakoptics technique based on the use of finite element method is developed in this paper. This method enables the analysis of large microwave structures by computation of subdomains. The algorithm is validated on a test case of a step in width finline discontinuity.

An hybrid formulation combining FDTD and TDPO

The finite difference time domain (FDTD) technique has been proven to be particularly well suited to study microwave circuits and antennas. However, its main limitation results from the increase in both computation time and memory storage when the studied structures become larger. On the other hand, asymptotic approaches, such as the physical optics are generally used to account for very large scatterers but are not valid to study small radiating structures. Several examples have been reported, in which a rigorous electromagnetic method was combined with an asymptotic approach in order to study small radiating sources close to large scatterers. So-called hybrid methods have been demonstrated as able to account for the environment of the antenna while maintaining the needed accuracy in the description of the antenna itself. This paper proposes a new hybrid technique that combines FDTD with the time domain physical optics (TPDO). As the whole approach is performed in the time domain, it is expected to be suitable for broadband analysis. Moreover, the physical optics allows the closeness between the small element and the large scatterer contrary to geometrical optics where the source is supposed to be far from the obstacle. Their support may even be the same but edge diffraction phenomena are not modeled.