Daniele Pinchera

Improving Channel Capacity Using Adaptive MIMO Antennas

A novel type of multiple-input multiple-output (MIMO) antenna employing parasitic elements is presented. A proper model for the parasitic-MIMO system is first discussed and then numerically and experimentally investigated. The results show that the proposed solution can significantly improve the performance of the communication system with a minimum impact on the complexity and cost of the overall system

A simple and robust adaptive parasitic antenna

A novel Uda-Yagi adaptive antenna is numerically and experimentally investigated. The antenna consists of an active element and a relatively large number of parasitic elements closed on two different loads selectable by simple electronic switches. The use of fuzzy-logic based cost function and self-adaptive biological beamforming algorithms allows to obtain quite good performances both in terms of signal to interference plus noise ratio and voltage standing wave ratio. The antenna is simple, low cost, and is robust with respect to mechanical and electrical tolerances and with respect to failures of some passive elements. Experimental results on two different prototypes confirm the good performances of the proposed antenna.

A Generalized Hybrid Approach for the Synthesis of Uniform Amplitude Pencil Beam Ring-Arrays

A generalized hybrid algorithm for the synthesis of uniform amplitude ring-arrays is introduced. The method exploits the analytical properties of the field radiated by a circular array in order to get advantages from the use of convex programming techniques. The method, aimed to the synthesis of circularly symmetric patterns, is very flexible and allows the use of different kind of feeds as well as stepped excitations. The synthesis procedure is demonstrated in the case of high-directivity pencil beam patterns.

Advances in the Deterministic Synthesis of Uniform Amplitude Pencil Beam Concentric Ring Arrays

We present some modifications to the deterministic approach (DA) recently proposed for fast design of aperiodic concentric ring arrays. Such modifications are aimed at improving the array performances in terms of directivity, side lobe level (SLL) and number of control points. In particular, an easy implementation of the size-tapering concept is provided within the processing scheme of the DA procedure; moreover, an improved collocation criterion is presented. Finally, a local optimization procedure, tailored to the concentric ring array case, is addressed.

Experimental Analysis of a Wideband Adaptive-MIMO Antenna

An experimental measurement campaign to investigate the wideband performance of an adaptive multiple-input multiple-output (AdaM) antenna consisting of two active and six parasitic antenna elements. The measurements are conducted over a 30 MHz bandwidth at a center frequency of 2.55 GHz and in a variety of locations in an indoor environment. The system uses a traditional two-element array at the transmitter and either a two-element traditional array or the AdaM antenna at the receiver. The results show that compared to the traditional array, the AdaM receive antenna can achieve the same throughput with an average power reduction of 2.7 dB and a maximum power reduction of 7.7 dB. The analysis further shows that the parasitic configuration works well over the entire frequency band, although improved power reduction can be obtained when the operation bandwidth is limited.

Synthesis of Isophoric Sparse Arrays Allowing Zoomable Beams and Arbitrary Coverage in Satellite Communications

In this paper, we address the synthesis of isophoric sparse ring arrays for full Earth coverage from a GEO satellite by means of steerable beams, switchable between two different widths. We show that to achieve such a zooming capability, we cannot simply tailor the array geometry to one of the patterns and then obtaining the beam zooming/shrinking by means of a phase-only control. Hence, we propose a novel synthesis approach that, in order to obtain the required beam zooming/shrinking by means of a phase-only control, tailors the layout geometry simultaneously to both the beams. Numerical results are presented to demonstrate the effectiveness of the proposed approach. The analysis also shows that the required beam re-configurability cannot be achieved for free. In particular, to radiate simultaneously the narrow and wide beams, with a beam-width ratio 1:5, we have to employ a number of control point 80% greater than that necessary to transmit only the narrow beam.

Radar array diagnosis from undersampled data using a compressed sensing/sparse recovery technique

A Compressed Sensing/Sparse Recovery approach is adopted in this paper for the accurate diagnosis of fault array elements from undersampled data. Experimental validations on a slotted waveguide test array are discussed to demonstrate the effectiveness of the proposed procedure in the failures retrieval froma small set of measurements with respect to the number of radiating elements. Due to the sparsity feature of the proposed formulation, the method is particularly appealing for the diagnostics of large arrays, typically adopted for radar applications.

An Investigation on UWB-MIMO Communication Systems Based on an Experimental Channel Characterization

The advantages of multiple-input multiple-output (MIMO) technology in ultrawideband (UWB) communication systems are investigated evaluating the channel capacity from measurements taken in indoor environments. The results suggest that in practical instances spatial diversity is more attractive than spatial multiplexing for ultrawideband systems.

Plane-Wave Generators: Design Guidelines, Achievable Performances and Effective Synthesis

The aim of this paper is to investigate the main aspects of the synthesis of plane wave generators (PWGs) i.e., arrays capable of emulating a plane wave, or a superposition of plane waves, in a given region. In particular, we introduce new figures of merit, particularly suitable for PWG synthesis procedures, and simple guidelines regarding size and shape of the PWG, as well as the number of radiating sources needed to synthesize the required plane waves. The performance limits of a PWG are analyzed, in terms of indexes related to the stability of the solution and to the level of the field amplitude on the lateral walls of the anechoic chamber in which the PWG is placed. Finally we present a synthesis method for PWGs, based on a planar sparse array architecture. Starting from the previously achieved results, a novel effective synthesis procedure is introduced. By means of such a procedure we are also able to take explicitly into account the mechanical and electrical tolerances in the PWG realization. In such a way we can assure the best performances, given the unavoidable errors in the positioning and excitation of the radiating elements.

A Sparse Recovery Approach for Pattern Correction of Active Arrays in Presence of Element Failures

The aim of this letter is to propose a novel approach based on sparse recovery technique for real-time correction of the pattern of active arrays in presence of failures of radiating elements. The failures are identified without interfering with the normal array operation, using a small number of probes placed around the array. After identifying the faulty elements, the aperture is reconfigured in order to reduce the pattern degradation as much as possible.