Reggio Calabria (RC), 89124, Italy

Inverse scattering as design tool

The possibility of design innovative EM devices through the inverse scattering (IS) framework has been investigated at LEMMA in the last years.

Interestingly, by taking advantage from the already available theories and tools well assessed for imaging/recovery problems, a number of approaches have been proposed for the design of dielectric devices based on a simple change of the IS point of view. As a matter of fact, by substituting the measurements of the scattered field (i.e., the data) with given specifications, the IS problem is turned into a design problem. Accordingly, the IS problem is be solved in order to determine the electromagnetic parameters of an object whose scattered field obeys certain assigned specifications rather than measurements.

A feasibility study on such a kind of design approach has been first carried out in [1] and then recently extended in [2].

Besides exploiting the possibility of using design facilitators to enforce desired properties on the profile to be synthesized, in [2] the direct synthesis of artificial materials (AM) based devices has been also proposed. These latter are structures composed by properly arranged small inclusions whose EM properties can be directly synthesized by solving the IS problem. In the particular case, the inclusions are arranged on concentric rings in order to realize a circularly symmetric device. Then, a smart approach has been also proposed to convert the so obtained ‘graded AM with a gradient of the refractive index’ (GAMr) into the so called ‘graded AM with a gradient of the filling factor’ (GAMf), wherein a local interchange between the complex permittivity and the radius of each inclusion allows to achieve a structure made up of a single material.

The developed tools have been demonstrated to be effective in a number of applications, such us the design of reconfigurable S/D [2] or multibeam [3] lens antennas and invisibility cloaks [4], [5].

In particular, the design of invisibility devices has been also carried out by exploiting  the well-known Diffraction Theorem by Devaney in order to properly customize the spectral coverage of the entire device (object+cloak) which does not radiate a scattered field [6].

[1] O. M. Bucci, I. Catapano, L. Crocco, and T. Isernia, Synthesis of new variable dielectric profile antennas via inverse scattering techniques: a feasibility study. IEEE TAP, 53(4), 1287-1297, 2005. click here

[2] R. Palmeri, M.T. Bevacqua, A.F. Morabito, and T. Isernia, Design of artificial-material-based antennas using inverse scattering techniques. IEEE TAP, 66(12), 7076-7090, 2018. click here

[3] R. Palmeri and T. Isernia, Design of multibeam artificial dielectrics based lenses via inverse scattering techniques. 39th ESA Antenna Workshop, 2018. click here

[4] R. Palmeri, M.T. Bevacqua, A.F. Morabito, and T. Isernia, Inverse scattering methods as a tool for the design of GPCs devices, IEEE Conference on Antenna Measurements & Applications (CAMA), 2017. click here

[5] L. Di Donato, T. Isernia, G. Labate, and L. Matekovits, “Towards printable natural dielectric cloaks via inverse scattering techniques,” SciRep 7(1), 3680, 2017. click here

[6] R. Palmeri and T. Isernia, Volumetric Invisibility Cloaks Design Through Spectral Coverage Optimization. IEEE Access, 7, 30860-30867, 2019. click here