Absorbing Elements on the Basis of a Uniform Resistive Film for Realization of Wide Range of Power Attenuations of Radio Signals

2018 ◽  
Vol 23 (5) ◽  
pp. 477-485
Author(s):  
V.D. Sadkov ◽  
◽  
K.S. Fomina ◽  
A.V. Pilkevich ◽  
◽  
...  
Keyword(s):  
Resistive Film ◽  
Wide Range ◽  
Radio Signals ◽  
Absorbing Elements

Thin-Film Absorbing Elements of Adapter-Attenuators for HIC

2021 ◽  
Vol 26 (6) ◽  
pp. 521-532
Author(s):  
A.V. Pilkevich ◽  
◽  
V.D. Sadkov ◽  
Keyword(s):  
Integrated Circuits ◽  
Power Density ◽  
Potential Gradient ◽  
Pulse Mode ◽  
Transformation Coefficient ◽  
Resistive Film ◽  
Input And Output ◽  
Wide Range ◽  
Film Element ◽  
Absorbing Elements

One of the urgent tasks in the design of hybrid integrated circuits (HIC) is the construction of adapter-attenuators – film absorbing elements providing a wide range of attenuations with specified values of input and output resistances. Known variants of adapter-attenuators based on a homogeneous and piecewise homogeneous resistive film provide (by introducing asymmetry in the dimensions of the input and output contacts, changing the location of a piecewise homogeneous resistive film, introducing dielectric or conductive regions) a resistance transformation coefficient of no more than 3 and 10–12, respectively. In this work, promising topologies of adapter-attenuators for HIC with a close to optimal profile of input and output contacts are proposed, which allow not only to obtain a wide range of transformation coefficients (more than 100), but also to reduce the maximum values of the potential gradient and power density by 10‒30 times. The rectangular topology calculations were made using the apparatus of the theory of functions of a complex variable. Modeling of the optimized topology of adapter-attenuators for HIC was carried out by the finite element method implemented in the Elcut software package. The calculated ratios and graphs showing the relationship of attenuation, the transformation coefficient, the gain in the value of the potential gradient and the power density, depending on the ratio of the size of the film element and the resistivity of the resistive films used, have been provided. The features of adapter-attenuators fitting have been considered. The results obtained are especially important for the pulse mode of operation of adapter-attenuators’ film element for HIC.

scholarly journals A weighting system to build physical layer measurements maps by crowdsourcing data from smartphones

2020 ◽  
Vol 9 (3) ◽  
pp. 211
Author(s):  
Hosam Alamleh ◽  
Ali Abdullah S. AlQahtani
Keyword(s):  
Mobile Devices ◽  
Access Point ◽  
Physical Layer ◽  
Network Coverage ◽  
Wide Range ◽  
Different Types ◽  
Radio Signals ◽  
Data Points ◽  
And Performance ◽  
Map Accuracy

<p>Mobile devices can sense different types of radio signals. For example, broadcast signals. These broadcasted signals allow the device to establish a connection to the access point broadcasting it. Moreover, mobile devices can record different physical layer measurements. These measurements are an indication of the service quality at the point they were collected. These measurements data can be aggregated to form physical layer measurement maps. These maps are useful for several applications such as location fixing, navigation, access control, and evaluating network coverage and performance. Crowdsourcing can be an efficient way to create such maps. However, users in a crowdsourcing application tend to have different devices with different capabilities, which might impact the overall accuracy of the generated maps. In this paper, we propose a method to build physical layer measurements maps by crowdsourcing physical layer measurements, GPS locations, from participating mobile devices. The proposed system gives different weights to each data point provided by the participating devices based on the data source’s trustworthiness. Our tests showed that the different models of mobile devices return GPS location with different location accuracies. Consequently, when building the physical layer measurements maps our algorithm assigns a higher weight to data points coming from devices with higher GPS location accuracy. This allows accommodating a wide range of mobile devices with different capabilities in crowdsourcing applications. An experiment and a simulation were performed to test the proposed method. The results showed improvement in crowdsourced map accuracy when the proposed method is implemented.</p>

scholarly journals Clustering Algorithms and Validation Indices for a Wide mmWave Spectrum

Information ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 287 ◽  
Author(s):  
Bogdan Antonescu ◽  
Miead Tehrani Moayyed ◽  
Stefano Basagni
Keyword(s):  
Communication Systems ◽  
Clustering Algorithm ◽  
Radio Channel ◽  
Clustering Algorithms ◽  
Wireless Communication Systems ◽  
Cluster Validity Indices ◽  
Validity Indices ◽  
Wide Range ◽  
Radio Signals ◽  
Urban Scenario

Radio channel propagation models for the millimeter wave (mmWave) spectrum are extremely important for planning future 5G wireless communication systems. Transmitted radio signals are received as clusters of multipath rays. Identifying these clusters provides better spatial and temporal characteristics of the mmWave channel. This paper deals with the clustering process and its validation across a wide range of frequencies in the mmWave spectrum below 100 GHz. By way of simulations, we show that in outdoor communication scenarios clustering of received rays is influenced by the frequency of the transmitted signal. This demonstrates the sparse characteristic of the mmWave spectrum (i.e., we obtain a lower number of rays at the receiver for the same urban scenario). We use the well-known k-means clustering algorithm to group arriving rays at the receiver. The accuracy of this partitioning is studied with both cluster validity indices (CVIs) and score fusion techniques. Finally, we analyze how the clustering solution changes with narrower-beam antennas, and we provide a comparison of the cluster characteristics for different types of antennas.

scholarly journals Detection of unmanned aerial vehicle using radio wave scatter on acoustic disturbances of the environment created by aircraft

Radiotekhnika ◽  
2021 ◽  
pp. 122-130
Author(s):  
V.M. Kartashov ◽  
O.I. Kharchenko ◽  
V.A. Pososhenko ◽  
V.I. Kolesnik ◽  
A.B. Yegorov ◽  
...  
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Unmanned Aerial Vehicle ◽  
Technical Problem ◽  
Technical Problems ◽  
Acoustic Disturbances ◽  
Aerial Vehicles ◽  
Wide Range ◽  
Radio Signals ◽  
Range Of Functions ◽  
Aerial Vehicle

Unmanned aerial vehicles (UAVs) have recently become widespread, because they are capable of performing a wide range of functions useful for mankind. At the same time, UAVs are a source of potential threats in a number of areas of human activity, namely, military, economic, and everyday life. Therefore, an urgent scientific and technical problem of detecting and observing UAVs has been formed recently to prevent them from performing unauthorized actions. The main means of UAV surveillance are radar (both active and passive), optical, infrared, acoustic stations, as well as complex systems in which joint processing of information obtained using these information channels is carried out. However, in general, the scientific and technical problem of monitoring UAVs, especially small UAVs, remains unresolved: the efficiency of UAV detection using all these methods remains insufficient, and the needs of practice are far from being fully satisfied with the available means. This article is devoted to the analysis of currently known scientific and practical results aimed to assess the possibility of detecting UAVs by radio signals scattered by acoustic disturbances of the environment created by UAVs, and to formulate urgent scientific and technical problems in this aria of knowledge.

Recent Applications of High Resolution Electron Microscopy to Crystalline Arrays of Virus Particles

1978 ◽  
Vol 36 (3) ◽  
pp. 470-482 ◽  
Author(s):  
R.W. Horne
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Analytical Techniques ◽  
Staining Technique ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Full Potential ◽  
Virus Particles ◽  
Resolution Electron ◽  
Wide Range

The technique of surrounding virus particles with a neutralised electron dense stain was described at the Fourth International Congress on Electron Microscopy, Berlin 1958 (see Home & Brenner, 1960, p. 625). For many years the negative staining technique in one form or another, has been applied to a wide range of biological materials. However, the full potential of the method has only recently been explored following the development and applications of optical diffraction and computer image analytical techniques to electron micrographs (cf. De Hosier & Klug, 1968; Markham 1968; Crowther et al., 1970; Home & Markham, 1973; Klug & Berger, 1974; Crowther & Klug, 1975). These image processing procedures have allowed a more precise and quantitative approach to be made concerning the interpretation, measurement and reconstruction of repeating features in certain biological systems.

Microfabrication research at the National Submicron Facility

1983 ◽  
Vol 41 ◽  
pp. 86-89
Author(s):  
E.D. Wolf
Keyword(s):  
Integrated Circuits ◽  
Particle Physics ◽  
High Speed ◽  
New Technology ◽  
High Energy ◽  
High Energy Particle ◽  
New Science ◽  
Wide Range ◽  
Intermediate Domain ◽  
Circuit Function

Most microelectronics devices and circuits operate faster, consume less power, execute more functions and cost less per circuit function when the feature-sizes internal to the devices and circuits are made smaller. This is part of the stimulus for the Very High-Speed Integrated Circuits (VHSIC) program. There is also a need for smaller, more sensitive sensors in a wide range of disciplines that includes electrochemistry, neurophysiology and ultra-high pressure solid state research. There is often fundamental new science (and sometimes new technology) to be revealed (and used) when a basic parameter such as size is extended to new dimensions, as is evident at the two extremes of smallness and largeness, high energy particle physics and cosmology, respectively. However, there is also a very important intermediate domain of size that spans from the diameter of a small cluster of atoms up to near one micrometer which may also have just as profound effects on society as “big” physics.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

Observation of Atom Rows in Thorium Pyromellitate Using a Field Emission STEM

1977 ◽  
Vol 35 ◽  
pp. 80-81
Author(s):  
H. Todokoro ◽  
S. Nomura ◽  
T. Komoda
Keyword(s):  
Field Emission ◽  
Amorphous Carbon ◽  
Carbon Film ◽  
Dark Field Image ◽  
Dark Field ◽  
Amorphous Carbon Film ◽  
Atomic Size ◽  
Wide Range ◽  
A Chain

It is interesting to observe polymers at atomic size resolution. Some works have been reported for thorium pyromellitate by using a STEM (1), or a CTEM (2,3). The results showed that this polymer forms a chain in which thorium atoms are arranged. However, the distance between adjacent thorium atoms varies over a wide range (0.4-1.3nm) according to the different authors.The present authors have also observed thorium pyromellitate specimens by means of a field emission STEM, described in reference 4. The specimen was prepared by placing a drop of thorium pyromellitate in 10-3 CH3OH solution onto an amorphous carbon film about 2nm thick. The dark field image is shown in Fig. 1A. Thorium atoms are clearly observed as regular atom rows having a spacing of 0.85nm. This lattice gradually deteriorated by successive observations. The image changed to granular structures, as shown in Fig. 1B, which was taken after four scanning frames.

Development of a conical anode Fe-gun for low voltage SEM

1988 ◽  
Vol 46 ◽  
pp. 978-979
Author(s):  
T. Miyokawa ◽  
S. Norioka ◽  
S. Goto
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Low Voltage ◽  
Irradiation Damage ◽  
Cold Cathode ◽  
Virtual Source ◽  
Source Position ◽  
Electrostatic Lens ◽  
Electrostatic Lenses ◽  
Wide Range

Field emission SEMs (FE-SEMs) are becoming popular due to their high resolution needs. In the field of semiconductor product, it is demanded to use the low accelerating voltage FE-SEM to avoid the electron irradiation damage and the electron charging up on samples. However the accelerating voltage of usual SEM with FE-gun is limited until 1 kV, which is not enough small for the present demands, because the virtual source goes far from the tip in lower accelerating voltages. This virtual source position depends on the shape of the electrostatic lens. So, we investigated several types of electrostatic lenses to be applicable to the lower accelerating voltage. In the result, it is found a field emission gun with a conical anode is effectively applied for a wide range of low accelerating voltages.A field emission gun usually consists of a field emission tip (cold cathode) and the Butler type electrostatic lens.

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