Summary - Web del proyecto INVEMTA

This project comprises several research lines under the topic of inverse electromagnetic techniques with some innovative Near-Field (NF) algorithms and applications and experimental setups using antenna measurement facilities. Due to the NF orientation, full-wave integral equation formulations will be considered. One of the mainstays of the set of proposed techniques along the project is the Source Reconstruction  Method (SRM). Improvements and applications in antenna diagnosis (probe correction, phase retrieval, determination of safety volumes of radioelectric stations, super resolution for diagnosis of metamaterial based antennas) shape an important part of the project (Working Package 1).
Based on integral equation formulation, inverse scattering methods are proposed for material characterization, low-contrast object imaging (Born approximation) and arbitrary geometry imaging and material reconstruction with some proposed NF setups for numerical and experimental validation including the study of further usability in real applications (Working Package 2).
Based on the strategy and formulation of the SRM, a cooperative location technique for NF and FF configuration is proposed to be developed for application indoor scenarios. The influence of obstacles, number of sensors, multifrequency information (with low frequency bands for NLOS propagation) and EM noise will be studied. For the experimental validation of accuracy and usability study of the algorithms an initial 802.15.4 PHY link ZigBee network will be implemented for Received Signal Strength (RSS) configuration. Multifrequency and phase information will be considered through the integration of appropriate RF multiband transceivers as sensors of the network. Location techniques conforms another part of the project (Working Package 3).
Antenna pattern synthesis is another inverse electromagnetic topic in which the experience of the group in such topic is proposed to improve NF synthesis algorithms. In particular, synthesis techniques based on data learning and self-calibration methods are proposed, including their application to an NF UHF RFID tag reading system; all this configures other WP (Working Package 4).
In order to improve the antenna measurements and specially the scattering measurements of WP2, the spectral angular echo cancellation techniques developed in the last years by the research group (matrix pencil and FFT based methods), are proposed to be optimized minimizing the bandwidth necessary for their successful application, including the development of algorithms based on Support Vector Regression (SVR) techniques. Their implementation in NF configurations and its extension to the knowledge of only amplitude information for low-cost measurement ranges, complete this WP (Working Package 5).
Another specific application is the improvement of the accuracy of the analysis and design of reflectarrays antennas by the use of the SRM to characterize the real feeder and to compute the actual incident field on the reflectarray surface. The diagnostic of the reflector surface from measurements and the SRM together with the use of full-wave MoM method is proposed to establish accuracy benchmarking of reflectarray design techniques (Working Package 6).
A transverse part of the project is devoted to the RF/microwave circuitry for practical implementation of some of the previous tasks: oscillator based multi-carrier transceiver sensors and compact multiband antennas for the proposed full-wave location techniques; the development of injection-locked harmonic self-oscillating mixer (HSOM) circuits for their implementation in different types of active antennas (retro-directive antennas, beamforming applications in RFID systems, and reflectarrays). The development of nonlinear analysis and optimization techniques for the design of rationally injection locked oscillators and harmonic balance and transient envelope simulation is also considered in this WP (Working Package 7).