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A method is presented for scattering of a plane wave by a perfectly conducting cylinder (PEC) buried near a two-media interface. Surface equivalence principle is employed to form a set of coupled integral equations. The unknown perturbed equivalent electric currents over the infinite interface are expressed in terms of the difference in current with cylinder present case and the exact physical optics...
In order to optimize the user experience and solve logistical and security issues, many systems require the physical location information from objects and people. Indoor positioning systems (IPSs) based on more than one technology can improve localization performance by leveraging the advantages of different technologies. This work proposes a hybrid IPS able to estimate the item-level location of...
We consider the channel estimation for millimeter-wave (mmWave) cellular systems in this paper. Because of the limitation of the hybrid RF/digital beamforming and the adoption of large-scale antennas, the acquisition of channel state information (CSI) is challenging. By exploiting the joint spatially sparse nature of practical mmWave channels, we develop a novel channel estimation algorithm based...
The main goal of this work is to present a planar director added coplanar Vivaldi antenna with improved impedance bandwidth, directivity for microwave breast imaging applications. Three stage design procedure is proposed to enhance the directivity and impedance bandwidth. Proposed antenna operates from 1.3GHz to 7.09GHz which fractional bandwidth is over 138%. The directivity of the proposed antenna...
In this paper, we introduce the concept of Twin-Antenna system for Energy Sensing and Low-Noise blind deconvolution using Field-Field Correlations. The holographic principle seen as a bridging connection between the geometry and information content of space-time is introduced for exploiting the Covariant Entropy bound. The Entropy-to-Energy and Entropy-to-Surface-Area bounds open new possibilities...
This paper investigates the effects of bending on the performance of a flexible dual-band printed monopole antenna designed to work for GPS, WLAN, and WiMAX applications. The antenna is printed on a Polyimide substrate with a relative permittivity of 4.3 and thickness of 25 pm. The antenna is fed by a coplanar waveguide transmission line to enhance the impedance matching over the wide operating bandwidth...
Among wireless system designers and practitioners there exists a degree of confusion concerning the definitions, constraints, and numerical values related to the transition between and boundaries of antennas' near and far diffraction regions. This work provides a critical review of popular misconceptions regarding this problem, investigates important physical and mathematical issues behind their origins,...
A corrugated horn incorporated with a broadband microwave window, has been designed, manufactured and measured. Operating over a wide bandwidth of 90–100 GHZ this horn achieved a high Gaussian content, over 99%, with a low microwave reflection, below −27 dB. The performance of the corrugated horn was confirmed through measurement using a vector network analyzer (VNA).
Validation of radiated emission measurement sites is usually performed through normalized site attenuation (NSA) measurements in 30 MHz to 1 GHz using broadband antennas, as established in such standards as ANSI 63.4 and CISPR 16-1-4. By the standard method, it is typical to use a biconical antenna in the 30 MHz to 200 MHz range and a log-periodic dipole antenna in the 200 MHz to 1 GHz range. Meanwhile,...
DC-DC buck converters are widely used in modern automotive applications due to their high power efficiency. However, they are also a major cause of electromagnetic emissions due to the nature of the fast switching voltages and currents. In modern automobiles there are as many as 24 antennas [2015], and the number will continue to increase in coming years. The close proximity of electronic modules...
Common mode signals on flexible cables often cause unwanted EMI. Common mode currents can be controlled by applying electromagnetic absorbing materials to the flexible cables. This work presents a set of specially designed test apparatuses that allow the performance of absorbing materials to be estimated for three typical structures known to radiate: monopole antennas, loop antennas, and transmission...
We have published a ground-coupled GPR antenna array, which consists of one transmitter and five receivers, for in situ estimation of the thickness and dielectric permittivity of an asphalt pavement layer [1]. In this paper, we optimize the design of the antipodal Vivaldi antenna to pursue a higher resolution through reducing the late-time ringing. Furthermore, an off-ground antenna array is assembled,...
This paper presents the development of a new pluggable combined low-frequency antenna, involving three frequencies of 12.5MHz, 25 MHz, and 50MHz, aiming to solve the current problems of the small detection range and low precision in mine disaster sources detection in China. Compared with many existing antennas, the novel designed plate-type structure antenna can enhance the directivity and reduce...
The NeTTUN (New Technologies for Tunnelling and Underground Works) Project involves a consortium of 23 industrial, research & development laboratories and small and medium enterprise organizations across 9 countries in Europe; the ultimate goal is to enable groundbreaking change in the construction and maintenance of tunnels. Most existing ground prediction methods require the stopping of excavation...
In this paper, we deal with the problem of the size of the investigation domain in a 2D linear inversion algorithm applied to GPR data. Linear inverse scattering approaches involve the problem of the computational burden associated with the inversion of a matrix when regularization schemes are adopted. In real GPR applications, the domain of interest is significantly large in terms of probing wavelength...
Several data fusion approaches have been developed to maximize both resolution and characterization depth for GPR. In this study, we propose a new physically-based method to merge multi-frequency radar data coming from different antennas. The strategy relies on the removal of antenna effects and the subsequent fusion of the resulting Green's functions in the frequency domain. We validated the approach...
Limestone is a widely used building material. Its degradation process is strongly linked to the water content, to which the radar waves are sensitive. In this paper, a model of stepped-frequency radar (SFR) wave propagation through partially wet limestone is proposed, in order to study the water transfer front in limestone. We assume the limestone as a two-layer (dry/wet) lossy medium and use an analytical...
Recently, a public attention to ground subsidence due to the subsurface cavities in the urban area is growing. To prevent such catastrophe, a ground-penetrating radar (GPR) technique is being widely used to image and detect roadbed cavities. In this paper, properties in timedomain of antenna configurations are investigated to construct a bistatc GPR system. The system is categorized into two types:...
In this paper we cope with the problem of the evaluation of the propagation velocity of the electromagnetic waves in the soil from diffraction hyperbolas. In particular, some limits of the well known method of the diffraction hyperbolas are put into evidence and are partially overcome by means of a sequential migration algorithm, which provides a fast, easy, and reliable technique, not requiring separable...
This work is focused on solving significant problems of conventional reflectarrays, i.e., beam dispersion and narrow bandwidth. In this paper, a multi-frequency phase matching method is used for wideband design with a fixed beam direction. A 32 × 50 offset-fed wideband terahertz reflectarray antenna, working in 0.225 ∼ 0.325THz, based on novel single-layer elements with a large and linear phase response,...
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