Leonardo Lizzi

Optimization of a Spline-Shaped UWB Antenna by PSO

This letter presents the design of a planar antenna for ultrawideband (UWB) applications with a bandwidth of 5.5 GHz over 3.7 to 9.2 GHz and return loss values lower than -10 dB. The antenna geometry is described in terms of a spline-based representation whose control parameters, together with other geometrical descriptive quantities, are determined through a suitable particle swarm optimizer (PSO) in order to fit the UWB requirements. Representative results of both numerical and experimental validations are reported in order to assess the performance of the prototype as well as to give some preliminary indications on the reliability and effectiveness of the whole synthesis approach

A Miniaturized UWB Antenna for Wireless Dongle Devices

In this letter, a planar ultra wideband (UWB) antenna suitable for the integration in wireless universal serial bus (USB) dongles is described. The antenna has a bandwidth equal to 2 GHz from 3 GHz up to 5 GHz with return loss values below -10 dB in the whole frequency range. To comply with UWB system needs, the antenna presents good distortionless properties when employed in a TX/RX system. Moreover, thanks to its simple shape and miniaturized geometry, the proposed prototype can be easily integrated and printed on dongle PCBs. In order to assess the reliability and efficiency of the antenna, a selected set of results from the experimental validation are shown and compared with the outcomes of the numerical simulations carried out during the synthesis process.

Dual-Band Printed Fractal Monopole Antenna for LTE Applications

In this letter, a dual-band fractal monopole antenna suitable for Long Term Evolution (LTE) standard is proposed. The antenna geometry is based on a perturbed planar Sierpinski fractal shape, whose geometrical descriptors are determined by means of a particle swarm optimization (PSO). The optimized antenna exhibits a good impedance matching within the LTE bands at 700 and 2600 MHz as well as a 24% size reduction with respect to a standard quarter-wave resonant monopole. The efficiency of the proposed antenna is assessed by means of both simulations and measurements.

A PSO-Driven Spline-Based Shaping Approach for Ultrawideband (UWB) Antenna Synthesis

Synthesis of ultrawideband (UWB) antennas by means of a particle swarm optimizer (PSO)-driven spline-based shaping approach is described. In order to devise a reliable and effective solution, such a topic is analyzed according to different perspectives: 1) representation of the antenna shape with a simple and efficient description; 2) definition of a suitable description of the UWB Tx/Rx system; 3) formulation of the synthesis problem in terms of an optimization one; 4) integration of the modelling of the UWB system into a computationally efficient minimization procedure. As a result, an innovative synthesis technique based on the PSO-based iterative evolution of suitable shape descriptors is carefully detailed. To assess the effectiveness of the proposed method, a set of representative numerical simulations are performed and the results are compared with the measurements from experimental prototypes built according to the design specifications coming from the optimization procedure. To focus on the main advantages and features of the proposed approach, comparisons with the results obtained with a standard parametric approach are reported, as well.

A Monopolar Quad-Band Antenna Based on a Hilbert Self-Affine Prefractal Geometry

In this letter, the design of a quad-band antenna is presented. The antenna has a planar geometry printed on a dielectric substrate orthogonal to a reference ground plane and its geometrical parameters are optimized starting from a Hilbert-like prefractal reference shape. The reliability of the synthesized antenna is assessed by means of a set of experimental tests to verify its compliance with the project constraints.

A DVBH/GSM/UMTS Planar Antenna for Multimode Wireless Devices

In this letter, the prototype of a planar antenna working in three different frequency bands and suitable to be integrated in multimode wireless devices is described. The antenna is fed by a single RF port without any matching circuit, and it operates in a DVBH channel and at GSM and UMTS frequency bands. Its dimension is of 0.15 lambda at the lower frequency band. The effectiveness and feasibility of the proposed antenna is assessed by means of both simulations and measurements.

A Nested Multi-Scaling Inexact-Newton Iterative Approach for Microwave Imaging

A microwave imaging technique based on the integration of the Inexact-Newton method within a multi-scaling strategy is proposed in the framework of the contrast field formulation of the electromagnetic inverse scattering. The inversion problem is solved by means of a nested procedure that considers three different logical levels: (a) an outer multi-focusing loop aimed at implementing a synthetic zoom for focusing the scatterer support within the investigation domain; (b) a local linearization of the original full-nonlinear inverse scattering function; and (c) a truncated Landweber inner loop devoted to regularize the arising ill-posed linear problem. Thanks to the features of the integrated approach, a reliable inversion technique able to suitably face the non-linearity and the ill-posedness/ill-conditioning issues of the imaging problem is designed. A numerical validation dealing with different objects, measurement setups, and noise conditions is carried out to assess the features and the potentialities as well as the limitations of the proposed strategy. Comparisons with bare approaches and other multi-resolution formulations are presented, as well.

Exploitation of Parasitic Smart Antennas in Wireless Sensor Networks

The integration of smart antennas in wireless sensor networks is a challenging and very attractive technical solution to improve the system capacity, the quality of service, and the power control. In this paper, some benefits coming from such an integration are experimentally assessed dealing with a set of test scenarios. Finally, some conclusions are discussed in order to point out current potentialities and limitations of the smart antennas integration to envisage future and possible advances.

Multiband Fractal Antenna for Wireless Communication Systems for Emergency Management

This paper is aimed at proposing a multiband fractal antenna suitable for wireless communication systems devoted to emergency management. The synthesis of the antenna is carried out by means of an iterative procedure based on a Particle Swarm Optimization (PSO) to identify the optimal descriptors of a perturbed Sierpinski geometry. The result is a miniaturized antenna exhibiting a good impedance matching within the Wi-Fi/WiMAX and Public Safety bands. The results from numerical validations and experimental tests are reported to demonstrate the effectiveness of the synthesized antenna as well as the reliability of the synthesis process.

Hybrid Design of a Fractal-Shaped GSM/UMTS Antenna

In this paper, the synthesis of a triple-band planar antenna working in the GSM (900 and 1800 MHz) and UMTS frequency bands is presented. As reference geometry, a hybrid pre-fractal shape has been adopted by integrating a Sierpinski and a Meander-line structure. The synthesis of the antenna has been performed by optimizing the descriptive geometrical parameters of the reference shape by means of a customized Particle Swarm strategy to comply with the electrical and geometrical requirements.