David Pouhe
Technical University of Berlin
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Featured researches published by David Pouhe.
IEEE Transactions on Electromagnetic Compatibility | 2008
David Pouhe; Gerhard Mönich
In all applications of the gigahertz transverse electromagnetic (GTEM) cell, there is an interplay between the equipment under test (EUT) and the cell reflecting metal walls, as represented by images of the EUT. Moreover, owing to the multiple reflections within the cell and to its tapering structure, the phenomenon of illumination and reillumination of the EUT can hardly be avoided. These problems, known as reactive effects of the cell, are investigated in this paper. A simple new approach for an efficient investigation of the interactions between the EUT and the cell is provided. Closed-form expressions for the reflection coefficient, the relative deviation in field, and the relative error in the induced current caused by the reactive effect of the cell are derived. Each of these expressions encompasses both the mutual influence of the EUTs radar cross section (RCS) and the reactive effects of the cell. It is shown that depending on the frequency-dependent phase factor ejpsi, strong and weak test conditions may occur since the overall incident field will exhibit maxima and minima. Hence, evidence showing that the total incident field impinging on the EUT generally deviates from the primary excited TEM field is provided. Moreover, the relative deviation in the field and the relative error in the induced current are quantified. Finally, the frequency dependence of the well-known one-third-rule of thumb is demonstrated.
international symposium on electromagnetic compatibility | 2009
David Pouhe; Gerhard Mönich
The GTEM cell essentially combines the elements of a transmission line and anechoic chamber. Power absorption is therefore a mutual phenomenon between the lumped element resistors and the high frequency absorbers. The different locations of the two absorbers require change in the energy flow. Investigation of this energy flow shows that essential higher order modes play a significant role in the transition between the two regime. In fact, once above the cutoff, higher order TM modes generate eddy regions within the cell. These eddies act as a barrier in the regions where they are located. As a consequence, most of the high frequency energy is linked to the lumped elements which can only absorbs low frequency energy. This results in a poor performance of the hybrid termination of the cell.
international conference on electromagnetics in advanced applications | 2011
David Pouhe; Olaf Sandstede; Gerhard Mönich
The suppression of non-essential modes is investigated in this work upon applying the network analysis. A simplified equivalent circuit model of the cell allowing separation of TEM and TM11 modes is developed. This approach enables the determination of the reflected power, power absorbed in the pyramid absorbers and dissipated in the lumped elements as well as separate evaluation of the attenuation for each mode although there is an energy transfer from one mode to another. The expected poor absorption character of the lumped elements with respect to essential higher order mode and the postulated high midway frequency of cells lined with pyramid absorbers are confirmed. Further, determination of the performance of each element of the circuit permits optimization of the cells parameters, thus enabling the enlargement of the overall usable test volume.
Progress in Electromagnetics Research B | 2017
Jean-Philippe Douarville-Blaise; David Pouhe; Junji Hirai
We present a topology of MIMO arrays of inductive antennas exhibiting inherent high crosstalk cancellation capabilities. A single layer PCB is etched into a 3-channels array of emitting/receiving antennas. Once coupled with another similar 3-channels emitter/receiver, we measured an Adjacent Channel Rejection Ratio (ACRR) as high as 70 dB from 150 Hz to 150 kHz. Another primitive device made out of copper wires wound around PVC tubes to form a 2-channels “non-contact slip-ring” exhibited 22 dB to 47 dB of ACRR up to 15MHz. In this paper we introduce the underlying theoretical model behind the crosstalk suppression capabilities of those so-called “Pie-Chart antennas”: an extension of the mutual inductance compensation method to higher number of channels using symmetries. We detail the simple iterative building process of those antennas, illustrate it with numerical analysis and evaluate there effectiveness via real experiments on the 3-channels PCB array and the 2-channels rotary array up to the limit of our test setup. The Pie Chart design is primarily intended as an alternative solution to costly electronic filters or cumbersome EM shields in wireless AND wired applications, but not exclusively.
IEEE Transactions on Electromagnetic Compatibility | 2012
David Pouhe
This paper provides a generalized approach for investigating the reactive effects of the gigahertz transversal electromagnetic cell using the method of moments. This method is based on a framework recently developed. Thin dipoles are used as canonical equipment under test (EUT) to provide a basic understanding of the effects of the interaction between the cell and EUT. Emphasis is put on the impedance variation and on the overall current distribution on the EUT, which are a measure par excellence of this coupling. The impact of the phenomenon of illumination and re-illumination along with the role of evanescent modes on the EUT has been demonstrated. It is shown that even for small EUTs the contribution of the fields excited by induced currents on the EUT and scattered back from cell walls cannot be, in general, neglected, as they contribute to the total field. The appeal of the approach resides in its simplicity and in imparting deep insights into the physics behind the mutual influence between the cell and the EUT.
Progress in Electromagnetics Research B | 2011
David Pouhe; Joel A. Tsemo Kamga; Gerhard Moenich
A new kind of fleld representation on the far fleld sphere is presented. This representation is based upon the polarisation states of the fleld. Polarisation states can easily be obtained upon determining the peculiar loci in the fleld. Depending on the polarisation state of the fleld, it is demonstrated that, either one of the magnetic or the electric dipole moments is dominant. Subsequently, criteria which may be applied to determine which dipole moment is responsible for the main radiation are derived. This characterization scheme which is a good flgure of merit for an antenna designer may be useful in mobile communications especially in identifying possible adverse efiects of RF flelds on human health. The approach is also helpful for EMC engineers seeking to characterize and identify radiation sources of equipment under test.
IEEE Transactions on Electromagnetic Compatibility | 2008
David Pouhe; Gerhard Mönich
In the above titled paper (ibid., vol. 50, no. 1, pp. 3-12, Feb 08), some comments related to Table I are missing. The corrected Table I is presented here.
international symposium on electromagnetic compatibility | 2007
David Pouhe; Gerhard Mönich
A simple novel approach for an efficient investigation of the interactions between the DUT and the cell is provided. Closed-form expressions for the reflection coefficient, the relative deviation in field and the relative error in induced current caused by the reactive effect of the cell are derived. Each of these expressions encompasses both the mutual influence of the DUT’s RCS and the reactive effect of the cell. It is shown that, depending on the frequency dependent phase factor ejͨ, strong and weak test conditions may occur since the overall incident field will exhibit maxima and minima. Hence evidence showing that the total incident field impinging on the DUT generally deviates from the primary excited TEM field is provided.
2007 2nd International ITG Conference on Antennas | 2007
David Pouhe; Cyprian Fusi; Gerhard Mönich
An improved multi-band broadband patch antenna with low dielectric constant (epsivr) suitable for personal communication services is presented. The improved antenna is obtained by introducing an angular displacement to the probe feed position. This offset of the probe from the x-axis also results in an additional antenna mode. Thus enabling its application for satellite TV communication in C-band. The impedance bandwidth, determined from the - dB return loss, is much greater than that of the same antenna without angular displacement.
international symposium on electromagnetic compatibility | 2006
David Pouhe
The behavior of reradiated fields from PCBs, with the radar cross section being the main parameter of interest is investigated in this work. A rigorous approach to predict radiation from PCBs in a GTEM cell is presented. The analysis is based upon the use of the reciprocity theorem in combination with the method of moment applied to the scattered field. Thus, yielding a generalized impedance matrix, whose determinant represents the characteristic polynomial of the scattering system. The effectiveness of the method is demonstrated by investigating some canonical circuit configurations and structures illustrating sources of fundamental EMI mechanism. The validity and the accuracy of the analysis becomes obvious in view of the one-to- one correlation with measurements. I. INTRODUCTION Printed-Circuits Boards (PCB) are of overriding importance in modern microelectronics where they undergo a continu- ous package complexity. Multilayer structures, split reference planes, various interconnects like bends, vias, etc. and trace circuit configurations in form of rectangular/circular loop, bent wire, linear dipoles, etc., are commonly mounted and present on hihgly integrated PCBs. These structures have led to an upsurge of interest in the analysis of the possible elec- tromagnetic interference (EMI) since they are often sources of unintentional radiated emission which can alter the EMC performance of real PCBs. Especially, in presence of an RLC- circuit, high-speed signals routed on the board may carry over resonances. These resonances tend, on their own, to carry interferences over much longer distances, which can not be predicted by field or gavanic coupling. The behavior of the reradiated field, with the PCB radar cross section (RCS) being the main parameter of interest, is therefore a good figure of merit in diagnosing radiation problems on the board. This paper addresses these particular points. Especially, it provides a rigorous approach to predict radiation from PCBs in a Giagahertz transverse electromagnetic (GTEM) cell. The analysis is based upon the use of the reciprocity theorem in combination with the application of the method of moment (MoM) to the scattered field yielding a generalized impedance matrix, whose determinant represents the characteristic poly- nomial of the scattering systems. After deriving an expression for the RCS in the next section, the generalized impedance matrix is evaluated for arbitrar- ily shaped wire radiating elements with a conducting plane reflector (section III). The real-axis method characterized by Sommerfeld-type integrals and moment-method solutions (1)- (3) is used to calculate elements of the impedance matrices. The effectiveness of the method is demonstrated by inves- tigating some canonical circuit configurations and structures illustrating sources of fundamental EMI mechanism (section IV). The validity and the accuracy of the analysis become ob- vious in view of the one to one correlation with measurements (section V).