Characteristic modal decomposition of reflection phase of a microstrip-patch reflectarray unit-cell

2016 ◽  
Author(s):  
Abdul Maalik ◽  
Roberto G. Rojas ◽  
Robert J. Burkholder
Keyword(s):  
Unit Cell ◽  
Modal Decomposition ◽  
Microstrip Patch ◽  
Reflection Phase

Reflectarray Resonant Element based on a Dielectric Resonator Antenna for 5G Applications

2021 ◽  
Vol 36 (7) ◽  
pp. 844-851
Author(s):  
Nur Sallehuddin ◽  
Mohd Jamaluddin ◽  
Muhammad Kamarudin ◽  
Muhammad Dahri
Keyword(s):  
Reflection Loss ◽  
Dielectric Resonator ◽  
Phase Shifter ◽  
High Gain ◽  
Unit Cell ◽  
Dielectric Resonator Antenna ◽  
Microstrip Patch ◽  
Reflection Phase ◽  
Phase Range ◽  
High Reflection

The performance of a proposed cross hybrid dielectric resonator antenna (DRA) element for dual polarization configuration operating at 26 GHz for 5G applications is presented in this paper. The new cross hybrid DRA unit cell is introduced which combines a cross shape DRA with a bottom loading cross microstrip patch. This technique of a bottom loading cross microstrip patch is chosen as the tuning mechanism (varying the length of the microstrip to tune the phase) instead of changing the DRA dimensions because of their ease of implementation and fabrication. By doing so, high reflection phase range with low reflection loss performance can be obtained, which is essential for a high bandwidth and high gain reflectarray for 5G applications. The design and simulation have been done using commercial software of CST MWS. The reflection loss, reflection phase and slope variation were analyzed and compared. A metallic cross microstrip patch of varying length placed beneath the DRA to act as the phase shifter to tune the phase and give smooth variation in slope with a large phase range. The proposed cross hybrid DRA unit cell provides a high reflection phase range of 342º and 1.8 dB reflection loss. The computed results are compared with experimental results revealing reasonable agreement, thereby confirming the viability of the design.

scholarly journals Innovative Reconfigurable Metasurface 2-D Beam-Steerable Reflector for 5G Wireless Communication

Electronics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1191
Author(s):  
David Rotshild ◽  
Efraim Rahamim ◽  
Amir Abramovich
Keyword(s):  
Beam Steering ◽  
Unit Cell ◽  
Reflection Phase ◽  
Low Profile ◽  
Unit Cells ◽  
Phase Range ◽  
New Type ◽  
Dc Bias ◽  
Communication Methods ◽  
Indoor And Outdoor

A tunable reflector component based on metasurface (MS) with a low profile and reduced mass is offered for indoor and outdoor 5G communication methods to overcome obstacles such as buildings, walls, and turns, and to allow wireless quasi-line of sight path communication at 37 GHz. Integrating varactors with MS unit cells allows tunability and reconfigurability. This approach was presented in many studies, with frequencies of up to K–band. However, today, higher frequencies are used, especially in communication. This work presents the design of a reconfigurable MS reflector, at Ka-band frequencies, based on a new type of resonant unit cell, with uniformed reflection for wide-incident-angular-range, and a simple stimulating DC bias for each MS unit cell, which allows a two–dimensional (2-D) continuous reflection phase manipulation. The unit cell provides a dynamic reflection phase range of over 300° at a wide bandwidth. Simulations of one-dimensional (1-D) and (2-D) at 37 GHz are presented. A steering range of up to ±48° was obtained for azimuth or elevation. A simultaneous independent 2-D beam steering range of up to ±10° in azimuth and up to ± 5° in elevation, allowing obstacles to overcome covering at a practical angular spatial cone of 20° and 10°, is presented.

scholarly journals Ultra-Wideband Reconfigurable X-Band and Ku-Band Metasurface Beam-Steerable Reflector for Satellite Communications

Electronics ◽  
2021 ◽  
Vol 10 (17) ◽  
pp. 2165
Author(s):  
David Rotshild ◽  
Amir Abramovich
Keyword(s):  
Beam Steering ◽  
Satellite Communications ◽  
Unit Cell ◽  
Ultra Wideband ◽  
Design Parameters ◽  
Continuous Control ◽  
Reflection Phase ◽  
X Band ◽  
Phase Reflection ◽  
Ku Band

A continuously reconfigurable metasurface reflector based on unit cell mushroom geometry that was integrated with a varactor diode is presented in this paper. The unit cell of the metasurface was designed and optimized to operate in the X-band and Ku-band, improving satellite communication’s quality of service. The losses mechanisms of continuous control over the unit cell phase reflection in beam steering resolution are considered and the analysis results are presented. The unit cell design parameters were analyzed with an emphasis on losses and dynamic reflection phase range. The unit cell magnitude and phase reflection are shown in the wide frequency bandwidth and showed a good agreement between all the measurements and the simulations. This metasurface enabled a high dynamic range in the unit cell resonant frequency range from 7.8 to 15 GHz. In addition, the reflection phase and absorption calibration are demonstrated for multiple operating frequencies, namely, 11 GHz, 12 GHz, and 13.5 GHz. Furthermore, design trade-offs and manufacturing limitations were considered. Finally, a beam-steering simulation using the designed metasurface is shown and discussed.

High-resolution structure determination by ALCHEMI

1983 ◽  
Vol 41 ◽  
pp. 178-181 ◽  
Author(s):  
Peter G. Self ◽  
Peter R. Buseck
Keyword(s):  
Site Occupancy ◽  
Real Space ◽  
Unit Cell ◽  
Bragg Angle ◽  
Electron Current ◽  
High Resolution Structure ◽  
Beam Incident ◽  
Crystallographic Planes ◽  
Electron Beam Incident ◽  
Resolution Structure

ALCHEMI (Atom Location by CHanneling Enhanced Microanalysis) enables the site occupancy of atoms in single crystals to be determined. In this article the fundamentals of the method for both EDS and EELS will be discussed. Unlike HRTEM, ALCHEMI does not place stringent resolution requirements on the microscope and, because EDS clearly distinguishes between elements of similar atomic number, it can offer some advantages over HRTEM. It does however, place certain constraints on the crystal. These constraints are: a) the sites of interest must lie on alternate crystallographic planes, b) the projected charge density on the alternate planes must be significantly different, and c) there must be at least one atomic species that lies solely on one of the planes.An electron beam incident on a crystal undergoes elastic scattering; in reciprocal space this is seen as a diffraction pattern and in real space this is a modulation of the electron current across the unit cell. When diffraction is strong (i.e., when the crystal is oriented near to the Bragg angle of a low-order reflection) the electron current at one point in the unit cell will differ significantly from that at another point.

The External Shape of Human γ GI Immunoglobulin from Crystal Sections

1971 ◽  
Vol 29 ◽  
pp. 428-429
Author(s):  
L. W. Labaw
Keyword(s):  
Molecular Weight ◽  
Sodium Phosphate ◽  
Osmium Tetroxide ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
X Ray ◽  
Large Molecular Weight ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Crystallographic Axes

Crystals of a human γGl immunoglobulin have the external morphology of diamond shaped prisms. X-ray studies have shown them to be monoclinic, space group C2, with 2 molecules per unit cell. The unit cell dimensions are a = 194.1, b = 91.7, c = 51.6Å, 8 = 102°. The relatively large molecular weight of 151,000 and these unit cell dimensions made this a promising crystal to study in the EM.Crystals similar to those used in the x-ray studies were fixed at 5°C for three weeks in a solution of mother liquor containing 5 x 10-5M sodium phosphate, pH 7.0, and 0.03% glutaraldehyde. They were postfixed with 1% osmium tetroxide for 15 min. and embedded in Maraglas the usual way. Sections were cut perpendicular to the three crystallographic axes. Such a section cut with its plane perpendicular to the z direction is shown in Fig. 1.This projection of the crystal in the z direction shows periodicities in at least four different directions but these are only seen clearly by sighting obliquely along the micrograph.

The orientation of sickle hemoglobin fibers within fascicles

1988 ◽  
Vol 46 ◽  
pp. 400-401
Author(s):  
Christopher A. Miller ◽  
Bridget Carragher ◽  
William A. McDade ◽  
Robert Josephs
Keyword(s):  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Relative Orientation ◽  
Unit Cell ◽  
Red Cell ◽  
High Ph ◽  
Sickle Hemoglobin ◽  
Polar Crystal ◽  
Helical Configuration

Highly ordered bundles of deoxyhemoglobin S (HbS) fibers, termed fascicles, are intermediates in the high pH crystallization pathway of HbS. These fibers consist of 7 Wishner-Love double strands in a helical configuration. Since each double strand has a polarity, the odd number of double strands in the fiber imparts a net polarity to the structure. HbS crystals have a unit cell containing two double strands, one of each polarity, resulting in a net polarity of zero. Therefore a rearrangement of the double strands must occur to form a non-polar crystal from the polar fibers. To determine the role of fascicles as an intermediate in the crystallization pathway it is important to understand the relative orientation of fibers within fascicles. Furthermore, an understanding of fascicle structure may have implications for the design of potential sickling inhibitors, since it is bundles of fibers which cause the red cell distortion responsible for the vaso-occlusive complications characteristic of sickle cell anemia.

Kinematical and Dynamical CBED Pattern Models: Increasing the Accuracy of the Unit-Cell Parameter Measurements Based on CBED Patterns

1990 ◽  
Vol 48 (2) ◽  
pp. 540-541
Author(s):  
I.N. Yadhikov ◽  
S.K. Maksimov
Keyword(s):  
Reciprocal Lattice ◽  
Unit Cell ◽  
Reciprocal Lattice Vector ◽  
Unit Cell Parameters ◽  
Lattice Vector ◽  
Cell Parameters ◽  
Accuracy Of Measurements ◽  
The Difference ◽  
Image Position ◽  
Convergent Beam

Convergent beam electron diffraction (CBED) is widely used as a microanalysis tool. By the relative position of HOLZ-lines (Higher Order Laue Zone) in CBED-patterns one can determine the unit cell parameters with a high accuracy up to 0.1%. For this purpose, maps of HOLZ-lines are simulated with the help of a computer so that the best matching of maps with experimental CBED-pattern should be reached. In maps, HOLZ-lines are approximated, as a rule, by straight lines. The actual HOLZ-lines, however, are different from the straights. If we decrease accelerating voltage, the difference is increased and, thus, the accuracy of the unit cell parameters determination by the method becomes lower.To improve the accuracy of measurements it is necessary to give up the HOLZ-lines substitution by the straights. According to the kinematical theory a HOLZ-line is merely a fragment of ellipse arc described by the parametric equationwith arc corresponding to change of β parameter from -90° to +90°, wherevector, h - the distance between Laue zones, g - the value of the reciprocal lattice vector, g‖ - the value of the reciprocal lattice vector projection on zero Laue zone.

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