Ricerc@Sapienza

An open resonator compatible with X-band commercial spectrometers for electron paramagnetic resonance was designed and built. In the design process, resonators with different shapes and dimensions were compared by using ad hoc defined cavity figures of merit. Three cylindrical cavities operating on TEX11 modes with X = 1 , 2, 3, were designed taking into account a coupling iris and a slit for microwave magnetic field leakage. The cavities were further improved toward the homogeneity of the 100 kHz modulation magnetic field.

This paper investigates the performance of an advanced imaging procedure for ground penetrating radar (GPR) operating in contactless configuration, i.e., when data are collected at variable distances from the air-soil interface. A data processing procedure is presented, based on an advanced implementation of a microwave tomographic approach. This improved version, recently proposed by the authors, is able of accounting for the near-field distribution generated by a directional transmitting antenna.

We present an image-domain adaptive likelihood ratio tests (LRT) detector for low-signature target detection in forward-looking ground-penetrating radar. We exploit multiview tomographic images of the scene under investigation to iteratively adapt the statistics of the targets and clutter arising from the interface roughness. Using numerical electromagnetic data, it is shown that the proposed adaptive LRT detector provides significantly lower false-alarm rates compared with its nonadaptive counterpart while providing comparable detection performance.

The applications of spaceborne GNSS reflectometry data over land are investigated in this work using the data collected by the UK TechDemoSat experimental mission. In order to quantify the sensitivity of the GNSS reflections to biomass and soil moisture from real data it is necessary to extract a quantity, like the surface reflectivity, as much as possible independent from the system parameters. At the same time, to understand the scattering mechanisms and potentialities and limitations of GNSS-R over land, an electromagnetic simulator has to be used and compared to the experimental data.

In this work, we propose an azimuthally-invariant periodic leaky-wave (LW) radiator for the generation of Bessel beams and X-waves by means of backward cylindrical LWs at millimeter wavelengths. A rigorous framework is first outlined to understand the theoretical constraints of such a novel design. A specific attention is devoted to the impact of the attenuation constant on the focusing properties of the generated Bessel beams. On this basis, a practical design is then proposed to meet the previous requirements.

A radially periodic two-dimensional leaky-wave antenna is studied for the generation of zeroth-order Bessel beams within a limited spatial region and over a wide frequency range. The antenna design is wideband and based on an annular metal strip grating placed on top of a grounded dielectric slab, supporting a cylindrical leaky wave with a fast backward spatial harmonic.

The capabilities of bistatic radar observations to estimate the wind field over the ocean are investigated in this paper. The work is based on the analysis of simulated data obtained through a well-established electromagnetic model, which accounts for the anisotropy of the ocean's spectrum and of second-order effects of the scattering phenomenon. Both co-polarized and cross-polarized C-band numerical data, obtained considering monostatic and bistatic configurations, are exploited to investigate on the existence of optimal configurations able to minimize the wind vector error estimation.

The electromagnetic scattering generated by agricultural tilled soils can be affected by a strong anisotropic component of the rough-surface profile. An accurate and reliable modeling of the normalized radar cross section, under both monostatic and bistatic geometries, is particularly important and desirable, especially for the correct estimation of the soil moisture content by means of satellite-based observations.

Power analysis attacks (PAAs), a class of side-channel attacks based on power consumption measurements, are a major concern in the protection of secret data stored in cryptographic devices. In this paper, we introduce the secure double rate registers (SDRRs) as a register-transfer level (RTL) countermeasure to increase the security of cryptographic devices against PAAs. We exploit the SDRR in a conventional advanced encryption standard (AES)-128 architecture, improving the immunity of the cryptographic hardware to the state-of-the-art PAAs.

The low power instrumentation amplifier (IA) presented in this paper has been designed to be the front-end of an integrated neural recording system, in which common-mode rejection ratio (CMRR), input referred noise and power consumption are critical requirements. The proposed IA topology exploits a differential-difference amplifier (DDA) whose differential output current drives a fully differential, high-resistance, transimpedance stage, with an embedded common-mode feedback loop to increase the CMRR. This stage is followed by a differential-to-single-ended output amplifier.