Full-Wave Modelling of Ground-Penetrating Radars: Antenna Mutual Coupling Phenomena and Sub-Surface Scattering Processes

Ground-penetrating radar (GPR) technology finds applications in many areas such as geophysical prospecting, archaeology, civil engineering, environmental engineering, and defence applications as a non-invasive sensing tool [3], [6], [18]. One key component in any GPR system is the receiver/transmitter antenna. Desirable features for GPR antennas include efficient radiation of ultra-wideband pulses into the ground, good impedance matching over the operational frequency band, and small size. As the attenuation of radio waves in geophysical media increases with frequency [9], [13], ground-penetrating radars typically operate at frequencies below 1GHz [4]. For either impulse [13] or steppedfrequency continuous-wave applications [17], the wider the frequency range, the better the range resolution of the radar. Continuous wave multi-frequency radars are advantageous over impulse radars in coping with dispersion of the medium, the noise level at the receiver end, and the controllability of working frequency. It requires, however, mutual coupling between the transmit (Tx) and receive (Rx) antennas, which determines the dynamic range of the sys-tem, to be kept as small as possible [12]

Approximating the Moments of Generalized Gaussian Distributions via Bell’s Polynomials †

Bell’s polynomials are used in many different fields of mathematics, ranging from number theory to operator theory. This paper shows a relevant application in probability theory aimed at computing the moments of generalized Gaussian distributions. To this end, a table containing the first values of the complete Bell’s polynomials is provided. Furthermore, a dedicated code for approximating the moments of the general distributions in terms of complete Bell’s polynomials is detailed. Several test cases concerning different nested functions are discussed.</p

A Wideband High-Gain Circularly-Polarized Dielectric Horn Antenna Equipped With Lamé-Axicon Stacked-Disk Lens for Remote Sensing, Air Traffic Control and Satellite Communications

A wideband high-gain circularly polarized (CP) shaped dielectric horn-lens antenna (SDHLA) operating in the frequency band between 6.7 and 18.2 GHz [fractional impedance bandwidth (FIBW) of 92.4%] with a 3-dB axial-ratio in the frequency range from 8.1 to 16.3 GHz [fractional axial-ratio bandwidth (FARBW) of 67.2%], is presented. The antenna, composed of a suitably shaped dielectric horn, integrated with a super-ellipsoidal-axicon dielectric lens made out of stacked thin dielectric disks, is mounted on a printed circuit board (PCB) where a microstrip line terminated with a wideband radial stub is used to excite a S-shaped slot through which the circular polarization is achieved. Parameterized 3D Lamé curves, describing the horn and lens profile, are used to optimize the antenna design. The antenna features a peak realized gain exceeding 13.1 dBi that is beneficial in a variety of applications, such as digital video broadcasting (DVB), remote sensing, weather monitoring, satellite communications, and air traffic control. The full-wave electromagnetic solver CST Studio Suite™, based on a locally conformal finite integration technique (FIT), was employed to design and characterize the antenna whose performances were found to be in good agreement with the experimental measurements.</p

W. M. Barnes Company, A Corporation v. Sohio Natural Resources Company, A Corporation, Formerly Sohio Petroleum Company, A Corporation : Appellant\u27s Brief

Appeal from the Judgment of the Fourth District Court for Uintah County Honorable George E. Ballif, Judg

Multi-Mode Antennas for Ultra-Wide-Angle Scanning Millimeter-Wave Arrays

In this paper, a novel multi-mode millimeter-wave antenna array with enhanced scan range and reduced scan losses is presented. The individual array element consists of a differentially fed microstrip patch on top of which a cylindrical dielectric resonator is integrated. The radiation pattern of the antenna element can be reconfigured by changing the phase offset between the feeding ports of the patch and the dielectric resonator to excite two distinct radiating modes. With such a feature, the field of view can be divided into two different subspaces, with the first one covering the angular range from -75to 0and the second one from 0to +75. In a 1 × 16 linear array configuration, the achieved scan range extends from -75to 75along the horizontal plane with a maximal gain loss of 3 dB, which is better than the ideal cos θ0 behavior. The proposed design operates in the frequency range between 27 GHz and 29.5 GHz and, thanks to its wide-scan capabilities, constitutes an effective solution for upcoming 5G/6G millimeter-wave wireless communications

A Novel Class of Super-Elliptical Vivaldi Antennas for Ultra-Wideband Applications

A novel class of complex-shaped antipodal Vivaldi antennas with enhanced impedance matching characteristics and an equivalent fractional bandwidth (FBW) of 166.8% is proposed. The reported antenna geometry is designed using the super-ellipse equation and implemented using an inexpensive FR4 laminate having a size of 170.7 mm × 134 mm × 0.2 mm. The presented low-cost, easy-to-fabricate radiating structure yields typical total efficiency, realized gain, and front-to-back ratio of 68%, 8.2 dBi, and 21.1 dB, respectively, across the operational frequency range. A parameter study of key geometrical features of the antenna is detailed in order to provide useful design guidelines while getting a better insight into the relevant physical behavior. Finally, a prototype is realized and characterized. The numerical results collected by full-wave simulation of the antenna structure are found to be in good agreement with the experimental measurements taken on the physical demonstrator

Accurate Time-Domain Modeling of Reconfigurable Antenna Sensors for Non-Invasive Melanoma Skin Cancer Detection

The full-wave electromagnetic characterization of reconfigurable antenna sensors for non-invasive detection of melanoma-related anomalies of the skin is presented. To this end, an enhanced locally conformal finite-difference time-domain procedure, based on the definition of effective material parameters and a suitable normalization of the electromagnetic field-related quantities, is adopted. In this way, an insightful understanding of the physical processes responsible for the performance of considered class of devices is achieved. This in turn is important in order to enhance the structure reliability, optimizing the design cycle. A suitable microelectromechanical-system-based sensor layout is finally discussed in details

Locally conformal FDTD modeling of MEMS-Based antenna sensors for melanoma detection

The full-wave characterization of reconfigurable antenna sensors for non-invasive detection of melanoma is presented. To this end, an enhanced locally conformal finite-difference time-domain numerical procedure, based on a suitable normalization of the electromagnetic field-related quantities, is adopted. In this way, a physical insight in wave diffraction phenomena occurring in the radar monitoring of skin cancers, as well as in the natural resonant processes responsible for the performance of the considered class of devices is achieved. This, in turn, is important in order to enhance the device reliability, so optimizing the design cycle. In this respect, a suitable microelectro-mechanical-system-based sensor layout is proposed

A cortical mechanism linking saliency detection and motor reactivity in rhesus monkeys

: Sudden and surprising sensory events trigger neural processes that swiftly adjust behavior. To study the phylogenesis and the mechanism of this phenomenon, we trained two male rhesus monkeys to keep a cursor inside a visual target by exerting force on an isometric joystick. We examined the effect of surprising auditory stimuli on exerted force, scalp electroencephalographic (EEG) activity, and local field potentials (LFP) recorded from the dorso-lateral prefrontal cortex. Auditory stimuli elicited (1) a biphasic modulation of isometric force: a transient decrease followed by a corrective tonic increase, and (2) EEG and LFP deflections dominated by two large negative-positive waves (N70 and P130). The EEG potential was maximal at the scalp vertex, highly reminiscent of the human 'vertex potential'. Electrocortical potentials and force were tightly coupled: the P130 amplitude predicted the magnitude of the corrective force increase, particularly in the LFPs recorded from deep rather than superficial cortical layers. These results disclose a phylogenetically-preserved cortico-motor mechanism supporting adaptive behavior in response to salient sensory events.Significance Statement Survival in the natural world depends on an animal's capacity to adapt ongoing behavior to unexpected events. To study the neural mechanisms underlying this capacity, we trained monkeys to apply constant force on a joystick while we recorded their brain activity from the scalp and, invasively, from the prefrontal cortex contralateral to the hand holding the joystick. Unexpected auditory stimuli elicited a biphasic force modulation: a transient reduction followed by a corrective adjustment. The same stimuli also elicited EEG and LFP responses, dominated by a biphasic wave that predicted the magnitude of the behavioral adjustment. These results disclose a phylogenetically-preserved cortico-motor mechanism supporting adaptive behavior in response to unexpected events

Modelling of implantable sensor packaging based on biocompatible polymers

Implantable devices are being used for long term healthcare and human body physiological monitoring of specific parameters. PDMS (poly-dimethyl-siloxane) can be used either for sensor or for packaging of the same sensor in many applications, notably in laparoscopy and laparotomy as feeler pin in order to help surgeons to touch specific tissues and to get a response based on the nature of the touched tissue (softness). The need of calibrated pressure on a tissue arises when we are in presence particular pathologies or impairments as: cancer issues, high risk of aneurism for aorta and brain, probable haemorrhage in touching capillaries, and so forth. This paper presents a packaging modelling of a build nanosensor to be used in a human body for surgery exploration as laparoscopy and laparotomy. A nanosensor is first build for common application and adapted for implantable applications, and a packaging is studied. The designed sensor is implemented by considering PDMS as polymeric material