Wide-Range Exciter with an Electrically Scanned Radiation Pattern

1966 ◽  
pp. 13-24 ◽  
Author(s):  
S. N. Ivanov ◽  
Yu. P. Ilyasov ◽  
G. N. Khramov
Keyword(s):  
Radiation Pattern ◽  
Wide Range

scholarly journals A Compact Single-Feed Circularly Polarized Microstrip Antenna with Symmetric and Wide-Beamwidth Radiation Pattern

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Xihong Ye ◽  
Mang He ◽  
Pingyuan Zhou ◽  
Houjun Sun
Keyword(s):  
Circular Polarization ◽  
Radiation Pattern ◽  
Microstrip Antenna ◽  
Return Loss ◽  
Axial Ratio ◽  
Compact Structure ◽  
Circularly Polarized ◽  
Wide Range ◽  
Half Power ◽  
Slot Aperture

A compact single-feed circularly polarized microstrip antenna is proposed to achieve symmetric radiation pattern over a wide range of observation angles. In order to reduce the radiation aperture and consequently broaden the circular polarization (CP) and the half power beamwidth (HPBW) of the antenna, a partially etched superstrate and a conducting cavity are employed in the design. Further, reasonable axial ratio (AR) and impedance bandwidths are realized within the compact structure by using a simple series crossed-slot aperture coupled feeding. As a consequence, the overall dimension of the fabricated prototype is 0.32λ0× 0.32λ0× 0.12λ0at the center operating frequency of 1.56 GHz, and a 3.0% overlapped bandwidth of 10 dB return loss (RL) and 3 dB AR is obtained. Within the bandwidth, symmetric CP radiation pattern over almost the entire upper hemisphere is observed and the HPBW is also increased from 60° to 106°.

scholarly journals Synthesis of a Luneburg lens with a flat surface using quasi-conformal transformation optics

2021 ◽  
Vol 23 (4) ◽  
pp. 68-73
Author(s):  
Andrey V. Lazarev ◽  
Andrey Yu. Kiselev ◽  
Anatoly M. Bobreshov ◽  
Grigory K. Uskov
Keyword(s):  
Radiation Pattern ◽  
Flat Surface ◽  
Antenna System ◽  
Wide Frequency Range ◽  
Main Lobe ◽  
Scanning Angle ◽  
Change Of Direction ◽  
Mathematical Algorithm ◽  
Wide Range ◽  
Luneberg Lens

Annotation In modern systems of radiolocation, navigation and communication, the requirements for antennas are becoming higher requirements every year, namely: operation in a wide frequency range, the ability to change of direction of the main lobe of the radiation pattern. Antenna systems with similar characteristics can be built using dielectric antenna beamforming structures. One of these structures is the Luneberg lens, the peculiarity of which is its spherical symmetry. However, the curved surface of this lens significantly complicates the placement of transmitting and receiving elements along it, which increases the complexity of constructing the entire antenna system. This paper proposes an algorithm for constructing a Luneberg lens with a flat surface. The lens was synthesized using the method of quasi-conformal optical transformations, the mathematical algorithm of which is also described in this work. The paper also presents the results of mathematical modeling of the antenna system using a Luneberg lens with a flat surface at different positions of the emitter relative to the center of the lens, as well as different cut angles. The simulation results show that the synthesized lens can be used to construct a multi-beam antenna system that allows the direction of the main lobe of the antenna radiation pattern to be rearranged over a wide range of angles. However, the scanning angles of this system are limited by the lens geometry, the larger the maximum scanning angle we choose, the more significant the influence of the side lobes on the radiation pattern becomes.

INVESTIGATION OF THE INFLUENCE OF THE METAMATERIAL PYRAMIDAL HORN INTEGRATED INTO THE CONSTRUCTION ON THE DIRECTIONAL DIAGRAM

2020 ◽  
pp. 107-113
Author(s):  
Е.А. Ищенко ◽  
Ю.Г. Пастернак ◽  
М.А. Сиваш ◽  
С.М. Фёдоров
Keyword(s):  
Radiation Pattern ◽  
Three Dimensional ◽  
Horn Antenna ◽  
Target Range ◽  
Directional Diagram ◽  
Specialized Software ◽  
Wide Range ◽  
Pyramidal Horn ◽  
Three Dimensional Models ◽  
Electrodynamic Modeling

Рассматривается метаматериал, который интегрирован в конструкцию пирамидальной рупорной антенны. Коммутация узлов метаматериала позволяет осуществлять управление диаграммой направленности рассматриваемой антенны. Для замыкания узлов в решетке метаматериала применяются pin-диоды, которые имеют в открытом состоянии эквивалентную схему, представляющую собой последовательное соединение сопротивления 2,1 Ом и индуктивности 0,6 нГн. Предложенная конструкция позволяет добиться управления характеристиками диаграммы направленности рассматриваемой антенны в широких пределах. Управление характеристиками антенн путем применения метаматериалов различных конструкций является передовым методом управления характеристиками излучателя. Для получения результатов применялось электродинамическое моделирование в специализированном программном обеспечении, на основе полученных результатов были построены диаграммы направленности в диапазоне работы рупорной антенны. Приведены результаты моделирования в виде трехмерных моделей исследуемых конструкций метаматериала, коммутируемых узлов; диаграммы направленности полученных антенн, на которых были определены изменения, вносимые коммутируемыми линиями метаматериала. Наибольшее изменение картин диаграмм направленности наблюдалось на частотах 13 и 14 ГГц, входящих в целевой диапазон работ рупорной антенны, основные исследования производились в H-плоскости рупора, так как коммутации подвергались вертикальные линии метаматериала The article discusses a metamaterial that is integrated into the structure of a pyramidal horn. Switching the nodes of the metamaterial allows you to control the radiation pattern of the antenna in question. To close the nodes in the lattice of the metamaterial, pin diodes are used, which in the open state have an equivalent circuit, which is a series connection of a resistance of 2.1 Ohm and an inductance of 0.6 nH. The proposed design makes it possible to achieve control over the characteristics of the radiation pattern of the antenna in question over a wide range. Antenna control by the use of metamaterials of various designs is an advanced method of a beam control. To obtain the results, electrodynamic modeling was used in specialized software, on the basis of the results obtained, directional patterns were constructed in the operating range of the horn antenna. The article presents the results of modeling in the form of three-dimensional models of the investigated metamaterial structures, switched nodes; directional diagrams of the received antennas, on which the changes introduced by the switched lines of the metamaterial were determined. The greatest change in the patterns of radiation patterns was observed at frequencies of 13 and 14 GHz, included in the target range of the horn antenna, the main studies were carried out in the H-plane of the horn, since the vertical lines of the metamaterial were subjected to commutation

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.

Comparison of Deterministic and Linear Cosine Spatial Filtering of Transmission Electron Micrographs

1972 ◽  
Vol 30 ◽  
pp. 596-597
Author(s):  
David A. Ansley
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Spatial Filter ◽  
Operating Conditions ◽  
Objective Lens ◽  
List Type ◽  
Spatial Filters ◽  
Transmission Electron ◽  
Wide Range

The coherence of the electron flux of a transmission electron microscope (TEM) limits the direct application of deconvolution techniques which have been used successfully on unmanned spacecraft programs. The theory assumes noncoherent illumination. Deconvolution of a TEM micrograph will, therefore, in general produce spurious detail rather than improved resolution.A primary goal of our research is to study the performance of several types of linear spatial filters as a function of specimen contrast, phase, and coherence. We have, therefore, developed a one-dimensional analysis and plotting program to simulate a wide 'range of operating conditions of the TEM, including adjustment of the:(1) Specimen amplitude, phase, and separation(2) Illumination wavelength, half-angle, and tilt(3) Objective lens focal length and aperture width(4) Spherical aberration, defocus, and chromatic aberration focus shift(5) Detector gamma, additive, and multiplicative noise constants(6) Type of spatial filter: linear cosine, linear sine, or deterministic

Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

1976 ◽  
Vol 34 ◽  
pp. 592-593
Author(s):  
Ernest L. Hall ◽  
J. B. Vander Sande
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Optical Devices ◽  
Semiconductor Compound ◽  
Wide Range ◽  
Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

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