Inverse Design of Artificial Materials Based Lens Antennas through the Scattering Matrix Method

The design of spatially varying lens antennas based on artificial materials is of high interest for their wide range of applicability. In this paper, we propose a novel design procedure relying on an inverse formulation of the scattering matrix method (SMM). Differently from many adopted approaches, which resort to global optimizations or homogenization procedures, the inverse SMM (I-SMM) allows the synthesis of optimal parameters (geometrical and/or electromagnetic) for the inclusions realizing the overall device in a very effective manner. With reference to the 2D TM case, the proposed tool has been successfully assessed through the synthesis of different kinds of lenses radiating a pencil beam

Faithful non-linear imaging from only-amplitude measurements of incident and total fields.

Applicability of inverse scattering based imaging procedures can be broadened by developing new approaches exploiting only amplitude data. As a matter of fact, this can open the way to simpler and less expensive measurement set-ups. In this respect, a two-step based procedure for solving electromagnetic nonlinear inverse scattering problems from only amplitude measurements of the total field has been recently proposed [1,2]. However, in these latter both amplitude and phase of the incident field are still required. In this contribution, we show the possibility of achieving this information from the measured amplitude distribution of the incident field on the observation domain. In particular, a three steps imaging technique which exploits only amplitude measurements of the total and incident fields has been developed. The proposed procedure has been tested against benchmark experimental data available in the literature. The obtained results fully confirm the possibility of achieving faithful reconstructions of unknown targets without performing any phase measurements and any approximation on the scattering equations involved in the inverse scattering problems

Effective Non-Iterative Phase Retrieval of 2-D Bandlimited Signals with Applications to Antenna Characterization and Diagnostics

The Phase Retrieval problem is dealt with for the challenging case where just a single set of (phaseless) radiated field data is available. In particular, even still emulating the solution of crosswords puzzles, we provide decisive improvements over our recent approaches. In fact, by exploiting bandlimitedness and a suitable set of intersecting curves, we definitively lower the computational complexity (thus eliminating drawbacks) of our previous techniques. Numerical examples, concerning applications of actual interest, support the given theory and confirm the effectiveness of the developed procedure

Monolithic patch antenna for dedicated short-range communications

Dedicated short-range communications (DSRCs) is a novel short- to medium-range wireless protocol designed for automotive use. The DSRC signals are circularly polarised and allocated in the 5.8 GHz band. Described is the development of a monolithic and compact patch antenna with left-hand circular polarisation intended for the on-board unit equipment of a DSRC system. The 40×60×2.455 mm fabricated prototype exhibits a circularly-polarised gain of about 5.52 dBc with a cross-polar discrimination of about 20 dB

An Effective Method for Borehole Imaging of Buried Tunnels

Detection and imaging of buried tunnels is a challenging problem which is relevant to both geophysical surveys and security monitoring. To comply with the need of exploring large portions of the underground, electromagnetic measurements carried out under a borehole configuration are usually exploited. Since this requires to drill holes in the soil wherein the transmitting and receiving antennas have to be positioned, low complexity of the involved apparatus is important. On the other hand, to effectively image the surveyed area, there is the need for adopting efficient and reliable imaging methods. To address these issues, in this paper we investigate the feasibility of the linear sampling method (LSM), as this inverse scattering method is capable to provide almost real-time results even when 3D images of very large domains are built, while not requiring approximations of the underlying physics. In particular, the results of the reported numerical analysis show that the LSM is capable of performing the required imaging task while using a quite simple measurement configuration consisting of two boreholes and a few number of multiview-multistatic acquisitions

assessing the capabilities of a new linear inversion method for quantitative microwave imaging

We investigate the imaging capabilities of a new linear microwave imaging approach, which allows to quantitative retrieve the complex permittivity distribution of unknown nonweak targets. To this end, we carry out a parametric numerical analysis for a canonical scatterer (a homogeneous dielectric cylinder with circular cross section) and derive a quantitative criterion to foresee the method's applicability. The reliability of the criterion is then tested against noncanonical scatterers to show the effectiveness of the method in imaging nonweak targets and in outperforming the linearized inversion method based on the standard Born approximation