Fabio Urbani

Experimental Analysis of Novel Single-Sided Left-Handed Metamaterial

This letter deals with the experimental analysis of a periodic planar structure composed of a diamond-shaped metallization on FR4 substrate. The novel design allows the metallization to be located only on one side of the dielectric slab, simplifying the manufacturing process. Issues related to the size of the unit cell versus wavelength are also addressed.

DESIGN OF AN ACTIVE INTEGRATED ANTENNA FOR A PCMCIA CARD

This paper presents the design and implementation of an Active Integrated Antenna (AIA) using a Voltage Controlled Oscillator (VCO) for applications in the Industrial Scientific Medical band (2.4 ÷ 2.4835 GHz). Surface Mounting Device (SMD) technology has been applied in the realization of the passive and active components, and low cost FR-4 dielectric slabs have been employed for the integration of the antenna and the active/transmissive circuits, residing, respectively, on the opposite faces of a Personal Computer Memory Card International Association (PCMCIA) card. The proposed layout makes use of a properly corrugated ground plane, i.e., a High Impedance Ground Plane (HIGP), to improve the antenna performances and to minimize the coupling between the radiating component and other possible radiating elements and/or electronic circuits residing nearby. The analysis and the design of the radiating element with the HIGP are based on a rigorous full wave Method of Moment (MoM) formulation developed in the Spectral Domain (SD), while the design of the active circuitry is developed through the commercial tool AWR Microwave Office. The final design of the component is obtained hybridizing the 254 Bilotti, Urbani, and Vegni two methods and applying a Genetic Algorithm (GA) optimization tool in order to take advantage of the HIGP, while keeping the geometrical dimensions of the antenna suitable for mounting on a PCMCIA card, and maintaining the antenna performances acceptable. The measured results show the performances of the VCO, an antenna gain of 19.4 dBi and an increased front-to-back radiation ratio compared to the one of the same antenna mounted on a standard Perfect Electric Ground Plane (PEGP). This result, thus, demonstrates the minimization of the interferences between the designed antenna and other possible radiating and transmissive devices residing nearby.

Experimental Characterization of Nanofilm Microstrip Antennas

We report on the experimental characterization of microstrip antennas where the radiating patch is entirely composed of nanofilms-chromium, aluminum, titanium, or nickel (the first two 15 nm thick and the latter two 20 nm thick). The nanofilms are excited indirectly through an aperture coupled feeding mechanism. The aluminum patch structure is seen to behave as an antenna with outstanding radiation performance and shows an ultrawideband response. The results demonstrate the potential for these antennas for system-on-chip, space application, and other specialized applications.

3D Localization and Tracking of Objects Using Miniature Microphones

Asystemfor accurate localization and trackingof remote objects is introduced, which employs a reference frame of four coplanar ultrasound sources as transmitters and miniature microphones that equip the remote objects as receivers. The transmitters are forced to emit pulses in the 17 - 40 kHz band. A central processing unit, knowing the positions of the transmitters and the time of flight of the ultrasound signals until they reach the microphones, computes the positions of the microphones, identifying and discarding possible false signals due to echoes and environmental noise. Once the microphones are localized, the position of the object is computed by finding the placement of the geometrical reconstructed object that fitsbest with the calculated microphones positions. The operating principle of the localization system is based on successive frames. The data are processed in parallel for all the microphones that equip the remote objects, leading to a high repetition rate of localization frames. In the proposed prototype, all the computation, including signal filtering, time of flight detection, localization and results display, is carried out about 25 times per second on a notebook PC.

Low cost compact active integrated antenna with a reactive impedance surface

This contribution presents the design and implementation of a voltage controlled oscillator active integrated antenna for applications in the industrial scientific medical band (2.4 + 2.4835 GHz). The proposed antenna is designed to be mounted on a PCMCIA card and exploits a two-layer reactive impedance ground plane to minimize the dimensions and increase the gain. The analysis and the design of the component are based on a hybrid employment of rigorous full wave formulations (used to model the antenna and its reactive ground plane) and nonlinear computer aided design techniques (used for the design of the linear and non linear modules of the antenna circuitry). Some results are presented to show the main features of the low cost active integrated antenna here proposed.

Outstanding performance of a nanofilm microstrip antenna

We report on the fabrication of a microstrip antenna with an ultra-thin Iron film patch with thickness of approximately 10 nm. The antenna showed excellent response in terms of performance and reliability. In addition, the antenna demonstrated potential for ultra-wide band applications. Such antennas may therefore have significant promise for system-on-chip, space application, and other specialized applications.

Asymptotic Evaluation of the Mom Excitation Vector for Probe-fed Microstrip Antennas

In this paper, we derive some original asymptotic expressions to speed up the computation of the excitation vector in the Method of Moments (MoM) numerical analysis of probe-fed planar microstrip antennas. These proposed expressions may be applied to the full-wave analysis of patch antennas in the spectral domain using the asymptotic Greens dyad of the planar integrated structure. It is shown in particular how planar patch antennas fed by a coaxial probe may be efficiently analyzed using fast converging 1D integrals to represent the MoM excitation vector, instead of employing the standard spectral bi-dimensional integrals. The numerical results underline the quick convergence of these new expressions and the consequent reduction of the computational time with respect to standard techniques.

Bloch impedance analysis for a left handed transmission line

In this study, the dispersion relation and the frequency dependence of Bloch impedance in a left handed transmission line (LH-TL) is carried out using the F-matrix formulation and Bloch-Floquet theorem. The artificial LH-TL formed by periodic lumped elements is described and the F-matrix, dispersion relation and the Bloch impedance are formulated according to this description. Numerical results for lossless and lossy LH-TL are presented and discussed.

Design of miniaturized double-negative microstrip antennas using electromagnetic parameter retrieval

In this paper the analysis of a microstrip antenna loaded with a double-negative (DNG) material is shown. The presented results can be applied easily to the design of planar antennas, arrays and Frequency Selective Surfaces (FSS). The advance in planar radiating structure design using non-conventional material with the objective of size reduction is carried out. A DNG material realized with a periodic repetition of split ring resonators (SRR) and metallic rods is adopted as the substrate of a 10 GHz microstrip antenna to achieve size reduction and improving the performance. The design is then compared with one that uses isotropic substrate (i.e. FR4). Comparison shows that the introduction of such a non-conventional medium allows the patch size to be reduced approximately by 57% and the bandwidth to be increased. Issues about size reduction and negative refractive index effects are further presented and discussed.

Patch antennas loaded by inhomogeneous substrates: a combined spectral domain - genetic algorithm approach

The optimized design of patch antennas with inhomogeneous loading materials is presented in this letter. The analysis and a first coarse design of the antennas is demanded to a numerical tool based on the Method of Moments (MoM) and on a full-wave formulation developed in the spectral domain that exploits both rigorous and asymptotic closed form expressions of the Greens function of a stratified integrated structure with inhomogeneous substrates. In order to match the specific prescribed requirements for the antennas, then, the optimization of the patch shape (fine design) is performed by a dedicated subroutine implementing the genetic algorithm search and integrated in the aforementioned MoM numerical tool. Some numerical results showing the capabilities of the code are finally presented.