- Fig.a – Salisbury screen absorber backed by a High-impedance surface (HIS).
- Fig.b – Salisbury screen absorber backed by a High-impedance surface (HIS).
- Fig. Prototype of the Fabry-Perot High-gain antenna configuration.
- Fig. Radiation patterns on the H and E plane of the Fabry-Perot antenna.
- Fig. Prototype of two realized FSS waveguide filters at 33 GHz.
- Fig. Frequency response of the multipoles waveguide filters at 33 GHz in single screen configuration (a) and in the cascaded configuration (b).
The activity concerns the design, realization and testing of novel devices based on metamaterials for Radar applications within the National Defence framework. The project is divided in three parts:
- Novel Rarar Absorbing Materials;
- Highly Directive antennas;
- Waveguide Metamaterials.
- The presented design methodology allows the introduction of a second resonance peak into a conventional Salisbury screen, by replacing the electric back plane with an artificial magnetic one. This configuration is well suited in applications where it could be necessary to have absorbing signals within two non adjacent frequency bands. By employing the proposed solution it would be possible, by simply using a conventional Salisbury screen and replacing the ground plane with an appropiately designed AMC surface, to achieve a reasonably thin structure operating at two bands of interest widely separated in the spectra.
- Antenna arrays are commonly employed to achieve high-gain antennas. The main drawback of this configuration are the high losses across the feeding network as the frequency raises. The use of a single radiating element inside a Fabry-Perot type cavity composed by a metamaterial partially reflective superstrate above a ground plane is proposed in order to dramatically increase the radiation efficiency of the printed high-gain antenna. As the reflectivity of the superstrate increases the Q factor of the Fabry-Perot cavity increases and, as a consequence, a more directive beam is achieved.
- A waveguide pass-band filter based on planar Frequency Selective Surfaces (FSS) has been designed manufactured and tested. The structure operates at 33 GHz and it is realized on GaAs substrate with gold metallization. A frequency selective profile with high-rejection stop bands and sharp transitions has been obtained by cascading three FSS filters characterized by different poles.