Francesco Belfiori

Coherent MIMO Array Design With Periodical Physical Element Structures

Multiple-input-multiple-output (MIMO) processing is a consolidated technique in communication systems thanks to the benefits that it offers in multipath fading environments. In recent years, studies have shown how the performances of conventional phased-array radar can be improved by using the same approach. This letter illustrates how the digital beamforming (DBF) theory can be extended to include MIMO arrays. In particular, the general description of a MIMO pattern is retrieved; accordingly, two different designs are described, which are aimed at obtaining optimal angular resolution and at controlling the sidelobes of the synthetic array pattern. An experimental result of a pattern synthesis is presented in the last section of the letter.

Array calibration technique for a coherent MIMO radar

In this paper we present a technique to estimate the calibration coefficients of a coherent Multiple-Input Multiple-Output (MIMO) array radar built on a printed circuit board (PCB). Due to the integrated structure and the MIMO nature of the system, a direct measurement of each antenna element behavior cannot be performed. The proposed method is based on the evaluation of the calibration parameters from the signal reflected by dominant targets, located at different range bins, and it does not require the a priori knowledge of their angular positions. Experimental validation of the presented technique has been done and the related results are illustrated.

Random transmission scheme approach for a FMCW TDMA coherent MIMO radar

In this paper the authors analyze the use of Time Division Multiple Access (TDMA) applied to coherent Multiple-Input Multiple-Output (MIMO) radar systems. One of the main limitations in exploiting the orthogonal condition in the time domain for MIMO radars is the reduction of the unambiguous Doppler interval. With respect to frequency modulated continuous waveform (FMCW) systems, the authors present a possible solution which is based on the introduction of a random selection of the active transmitter. The analytical representation of the signal model is described and the simulated results of the proposed approach are shown.

Analysis of a novel MIMO system for security applications

Recent years have shown how the performances of the standard radar systems can be significantly improved by using a multiple-input multiple output (MIMO) approach. MIMO technique is an already well studied method for communications applications thanks to the benefits that it offers in multipath fading environments. This paper is aimed to present the design of a new MIMO based, short range, surveillance radar for local area security purpose. One of the main addressed features to the system under consideration is the capability to provide full 360° azimuth coverage within its working area. The following analysis will be focused on the system structure description and on the first simulated results.

Polarimetric channels exploitation for improved target detection: Preliminary experiments with the PARSAX radar system

An extension of the PARSAX (which has originally been designed as a weather radar) signal processing with polarimetric target detection is described. The PARSAX radar has the unique possibility of simultaneously retrieving the full polarization back-scattering matrix (BSM) of the signal echo. The extension allows the system usage as a moving target indicator (MTI) surveillance and tracking radar. The new functionality realization uses the PARSAX system architecture, which comprises the digital conversion step at the intermediate frequency, and makes the overall processing chain fully reconfigurable in terms of processing algorithms. Furthermore, the polarimetric information, which comes from the simultaneous estimation of the BSM elements, is exploited in order to mitigate the false alarms and to improve the target detection performance. The experimental validation of the proposed processing has been performed by monitoring ground moving targets over the highways close to the EWI building of the Delft University of Technology.

Monopulse on transmit by means of orthogonal probing signals: Theoretical and experimental validations

Multiple-Input Multiple-Output (MIMO) radars represent a new class of sensors which combine orthogonal waveform transmissions and multichannel designs to improve specific performance of the system. Well known benefits are achieved in terms of either angular resolution, in the coherent MIMO scenario, or higher detection probability, in the statistical MIMO approach. In this paper the authors investigate the properties of the MIMO concept from another perspective. By exploiting the waveform agility characteristic of such systems, the simultaneous transmissions are used to synthesise independent channels which are then combined as for an angular monopulse detector. In fact, leading to a monopulse on transmit configuration. The analysis shows the theoretical improvement, in terms of angular accuracy, achieved by the MIMO array and the experimental results obtained by a monopulse on transmit with a simplified radar set-up.