Microwave Imaging from Limited-Angle Scattered Data using the Iterative Multi-Scaling Approach

In this paper, with reference to limited-angle data configurations, the performance of the nonlinear multi-scaling inversion approach (IMSA) is analyzed. Such an assessment is carried out by considering synthetically-generated as well as laboratory-controlled experimental data ('Marseille data') concerning two-dimensional dielectric scatterers. The obtained results demonstrate a satisfactory robustness and the reliability of the approach

A Hybrid Approach Based on PSO and Hadamard Difference Sets for the Synthesis of Square Thinned Arrays

A hybrid approach for the synthesis of planar thinned antenna arrays is presented. The proposed solution exploits and combines the most attractive features of a particle swarm algorithm and those of a combinatorial method based on the noncyclic difference sets of Hadamard type. Numerical experiments validate the proposed solution, showing improvements with respect to previous results. (c) 2009 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works

Detection, Location and Imaging of Multiple Scatterers by means of the Iterative Multiscaling Method

In this paper, a new version of the iterative multiscaling method (IMM) is proposed for reconstructing multiple scatterers in two-dimensional microwave imaging problems. The manuscript describes the new procedure evaluating the effectiveness of the IMM previously assessed for single object detection. Starting from inverse scattering integral equations, the problem is recast in a minimization one by defining iteratively (at each level of the scaling procedure) a suitable cost function allowing firstly a detection of the unknown objects, successively a location of the scatterers and finally a quantitative reconstruction of the scenario under test. Thanks to its properties, the approach allows an effective use of the information achievable from inverse scattering data. Morover, the adopted kind of expansion is able to deal with all possible multiresolution combinations in an easy and computationally inexpensive way. Selected numerical examples concerning dielectric as well as dissipative objects in noisy enviroments or starting from experimantally-acquired data are reported in order to confirm the usefulness of the introduced tool and of the effectiveness of the proposed procedure

Design of long-range, powerless RFID sensor at 10 GHz

The design of a radio frequency identifier (RFID) tag sensor based on the modulated scattering technique (MST) is presented. The tag works in the X band at 10 GHz and achieves an operative range of about 10 m with a limited amount of power. The power supply required by the transponder is obtained from the interogating electromagnetic field with a customised rectifying Chockcroft-Walton multiplier circuit. The communication between the reader and the tag is obtained using the standard EM4102 RFID protocol, the information is carried on by modulating the load of the tag antenna with a suitable switch circuit. The antenna tag, the rectifying circuit and the switch have been optimised to reach the maximum operative range. A tag prototype has been designed, fabricated and experimentally assessed. The obtained experimental results are quite good

A Planar Electronically Reconfigurable Wi-Fi Band Antenna Based on a Parasitic Microstrip Structure

This report presents the result of the synthesis of an horizontally polarized reconfigurable microstrip antenna

An Iterative Procedure for Combining the Advantages of a Multi-Frequency and Multi-Resolution Inversion Algorithm

Starting from the iterative multi�]scaling approach previously studied for monochromatic illuminations, two multi�]resolution strategies for dealing with multi�]frequency inverse scattering experiments have been developed. The first procedure is based on the integration of the iterative multi�]scaling algorithm into a frequency�]hopping reconstruction scheme, while in the second one the multi�]frequency data are simultaneously processed exploiting a multi�]resolution expansion of the problem unknowns. The numerical and the experimental analysis presented in this contribution concern with a preliminary assessment of the reconstruction effectiveness of the proposed approaches in comparison with a monochromatic multi�]step process. This is the author's version of the final version available at IEEE

A SVM-Based Multi-Resolution Procedure for the Estimation of the DOAS of Interfering Signals in a Communication System

In this work, the use of a planar antenna system for the estimation of the directions of arrivals (DOAs) of multiple signals impinging on the receiver has been considered. Towards this end, an efficient multi-resolution method based on a SVM-classifier is proposed for determining a probabilitic map of the DOAs of the unknown interfering signals. Numerical results dealing with multiple interferers scenarios in noisy environments are provided in order to assess the feasibility as well as the capability of the proposed approach

A Linear Multi-User Detector for STBC MC-CDMA Systems based on the Adaptive Implementation of the Minimum-Conditional Bit-Error-Rate Criterion and on Genetic Algorithm-assisted MMSE Channel Estimation

The implementation of efficient baseband receivers characterized by affordable computational load is a crucial point in the development of transmission systems exploiting diversity in different domains. In this paper, we are proposing a linear multi-user detector for MIMO MC-CDMA systems with Alamouti’s Space-Time Block Coding, inspired by the concept of Minimum Conditional Bit-Error-Rate (MCBER) and relying on Genetic-Algorithm (GA)-assisted MMSE channel estimation. The MCBER combiner has been implemented in adaptive way by using Least-Mean-Square (LMS) optimization. Firstly, we shall analyze the proposed adaptive MCBER MUD receiver with ideal knowledge of Channel Status Information (CSI). Afterwards, we shall consider the complete receiver structure, encompassing also the non-ideal GA-assisted channel estimation. Simulation results evidenced that the proposed MCBER receiver always outperforms state-of-the-art receiver schemes based on EGC and MMSE criterion exploiting the same degree of channel knowledge (i.e. ideal or estimated CSI)

A genetic algorithm-assisted semi-adaptive MMSE multi-user detection for MC-CDMA mobile communication systems

In this work, a novel Minimum-Mean Squared-Error (MMSE) multi-user detector is proposed for MC-CDMA transmission systems working over mobile radio channels characterized by time-varying multipath fading. The proposed MUD algorithm is based on a Genetic Algorithm (GA)-assisted per-carrier MMSE criterion. The GA block works in two successive steps: a training-aided step aimed at computing the optimal receiver weights using a very short training sequence, and a decision-directed step aimed at dynamically updating the weights vector during a channel coherence period. Numerical results evidenced BER performances almost coincident with ones yielded by ideal MMSE-MUD based on the perfect knowledge of channel impulse response. The proposed GA-assisted MMSE-MUD clearly outperforms state-of-the-art adaptive MMSE receivers based on deterministic gradient algorithms, especially for high number of transmitting users

Design and Analysis of Antenna Feeding Networks Based on the Rotman Lens Using Interval Analysis (IA)

A new method for the design of antenna array feeding networks has been proposed in this work. In particular, the considered feeding networks are based on the Rotman lens. By knowing the maximum errors on the fabrication tolerances, the arithmetic of intervals and interval analysis (IA) are used for determining the lower and upper bounds of the antenna feeding network parameters of interest. Representative and preliminary numerical results are reported to show the potentialities of the proposed method. An experimental X-band Rotman lens prototype has been designed, fabricated, and assessed. The obtained results are quite good