Homogenization of fine periodic shell structures for the finite element analysis of their shielding and reflection characteristics

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Dr. Gyimóthy Szabolcs
Department of Broadband Infocommunications and Electromagnetic Theory

In this thesis, I have studied the description of the electromagnetic waves in periodic structures, and deduced the solution for the plane wave excitation, in periodic structures along two coordinate axes. Based on this description, the solution for other arbitrary periodic structure can be given with the excitation of other analytic waveform.

I have determined different absorber sponges material properties by measurement. With these parameters, different structured and material properities pyramid RF absorber cells have been simulated by using COMSOL Multiphysics in the dependence of the incidence angle, polarization and frequency. Based on these simulations frequency and θ ( spherical coordinate ) incidence angle dependent surface impedance could be determined, because we found that the dependence of linear polarization direction ( α ) and φ ( spherical coordinate ) incidence angle is neglectable. The θ angle can be calculated directly from the incoming waves, thus neglecting the reflected components from the adjacent walls. Using that the simulation of the full anechoic chamber could be done in COMSOL.


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