PWB

PWB

Product by :PWB_logo

ONERA

 

Scope :

POWER BALANCE (PWB) models are developed in order to qualify and quantify electromagnetic interactions induced in an electrically large system from a macroscopic point of view.

Features :

The PWB code addresses EM problems in a frequency range where the system under test is larger than the wavelength. The method is a based on a statistical description of EM phenomena (as in a Mode Stirring Reverberating Chamber) and conservation of energy in oversized enclosures.

The entire EM problem is modelled as a topological network (as in classical EM topology) where nodes represent absorption phenomena, transfer of energy between EM volumes…
All elementary EM phenomena (or nodes) are supposed to be independent from each other and are therefore quantified via a coupling cross section. Finally, this network is solved via the BLT equation (as in CRIPTE for multiconductor transmission line applications) and mean power density/mean dissipated power at each node extremity of the initial network are calculated. This approach makes the assumption of linear EM problems and is developed in frequency domain.

In HIRF-SE, the PWB approach is an elementary brick of the proposed high-frequency scenario to solve the internal EM problem, the external environment being solved by any computer code able to calculate this environment at high frequency. In HIRF SE practical validations of coupling with OKTAL-SE’s SE-RAY asymptotic code have been demonstrated.

pwb1Figure 1: High Frequency scenario proposed in HIRF-SE including PWB approach

Consequently, to solve an EM problem at high frequency with the POWER BALANCE approach and computer code, one has to :

  •  Build the interaction diagram and its corresponding topological network by listing and linking all EM interactions and EM dissipative phenomena inside the system under test. An example is given below in Figure 2. The user can create, characterize and modify networks.

pwb2  Figure 2: Example of an EM problem and its modelling via the POWER BALANCE approach

  • Quantify and characterize all nodes of this network through coupling cross section (CCS) models. The coupling cross section is defined as the ratio between a dissipated power of a component and power density seen by this component. Under the assumption of independency of EM interactions, validated models of CCS of typical EM phenomena are available in the existing code :

        • losses in metallic and dielectric walls,
        • antennas,
        • dielectric “pseudo spherical” objects,
        • absorbing objects which have been experimentally characterized,transfer through apertures when EM environment on both sides are pseudo randomized (EM environment are considered as random plane wave spectrum, similar to EM environment in MSRCs). Various geometries of apertures can be considered (circular, slots, rectangular, ellipsoid, circular and rectangular gaskets, loaded apertures..)
        • wires. Wires are models as dissipative objects. In this case, this model is derived from the antenna theory.
  • Define source terms as incident power density generator or power generator. The PWB code is also able to process E-fields and H-fields computed by a 3D code on identified points of entry of the incident EM interference (as cockpit or windows for example).

  • Solve the BLT equation implemented in the PWB code in order to get induced mean power density and/or induced mean dissipated power at each extremity of branches and nodes.

Moreover, PWB offers the opportunity to compute and save mean CCS of the above mentioned EM phenomena but also equivalent CCS of sub-networks in order to store them in a data base and re-use them if necessary in other EM problems.

 

Screenshots :

 

pwb3 Figure 3: The PWB code in the CuToo platform

 

pwb4 pwb5

Figure 4: Combined application of PWB with SE-RAY on Evektor’s VUT100 and implementation in the framework (courtesy Evektor, EMCC and OKTAL-SE)

 

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 Figure 5: Application of PWB approach on Dassault’s F7X aircraft (HIRF-SE): topological results and application of HIRF SE’s pass-fail criteria approach (courtesy Dassault)

 

References :

  1. I. Junqua, J-P. Parmantier, F. Issac,
    A network formulation of the PWB method for high frequency coupling,
    Journal of Electromagnetics, October 2005

  1. I. Junqua, J-P. Parmantier, L. Guibert,
    Assessment of high frequency coupling in a generic object by the Power Balance method,
    EMC Zurich 2007, Munich, September 2007

  1. J-P. Parmantier, I. Junqua,
    EM Topology: from theory to application,
    Ultra-Wideband Short-Pulse Electromagnetics 7, Sabath, F.; Mokole, E.L.; Schenk, U.; Nitsch, D. (Eds.), pp 3-12, 2007, XVI
  1. I. Junqua, JP. Parmantier, F. Issac,
    A network formulation of the PWB method for high frequency EM coupling applications,
    Interactions Notes 576, November 2002

  1. Isabelle Junqua, Jean-Philippe Parmantier, Pierre Degauque,
    Field-to-Wire Coupling in an Electrically Large Cavity: a Semi-Analytic Solution,
    IEEE Transactions on EMC, Vol 52, n°4, pp 1034-1040 November 2010
  1. Isabelle Junqua, François Issac, Martine Liénard, Pierre Degauque,
    On the Power dissipated by an antenna in Transmit Mode or in Receive Mode in a Reverberation Chamber,
    IEEE Transactions on EMC, Vol 54, n°1, pp 174-180 February 2012

Contacts :

Solange Bertuol (solange[dot]bertuol[at]onera[dot]fr)

Jean-Philippe Parmantier (jean-philippe[dot]parmantier[at]onera[dot]fr)

Isabelle Junqua (isabelle[dot]junqua[at]onera[dot]fr)