scholarly journals Balanced gain for a square metaloop antenna

2019 ◽  
Vol 6 ◽  
pp. 3
Author(s):  
Hisamatsu Nakano ◽  
Ittoku Yoshino ◽  
Tomoki Abe ◽  
Junji Yamauchi
Keyword(s):  
Frequency Response ◽  
Radiation Pattern ◽  
Free Space ◽  
Loop Antenna ◽  
Circularly Polarized ◽  
Left Handed ◽  
The Difference

A square loop antenna implemented using a metamaterial line, referred to as a metaloop, is discussed. The metaloop radiates a counter circularly polarized (CP) broadside beam when the loop circumference equals one guided wavelength. The frequency response of the gain shows two different maximum values: gain G Lmax for a left-handed CP wave at frequency fGLmax and gain GRmax for a right-handed CP wave at frequency fGRmax, where GLmax is smaller than GRmax. In order to increase GLmax, while not affecting the original GRmax as much as possible (i.e. balance the gain), a parasitic natural conducting loop (paraloop), whose circumference is one free-space wavelength at fGLmax, is placed at height Hpara above the metaloop. It is found that the difference in the gains can be reduced by choosing an appropriate Hpara. The radiation pattern at fGLmax is narrowed by the paraloop, while the VSWR is not remarkably affected.

Modulation instability in nonlinear chiral fiber

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Demissie Jobir Gelmecha ◽  
Ram Sewak Singh
Keyword(s):  
Theoretical Model ◽  
Numerical Simulations ◽  
Pulse Propagation ◽  
Modulation Instability ◽  
Constitutive Relations ◽  
Gain Spectrum ◽  
Circularly Polarized ◽  
Left Handed ◽  
Simulation Results ◽  
The Difference

AbstractIn this paper, the rigorous derivations of generalized coupled chiral nonlinear Schrödinger equations (CCNLSEs) and their modulation instability analysis have been explored theoretically and computationally. With the consideration of Maxwell’s equations and Post’s constitutive relations, a generalized CCNLSE has been derived, which describes the evolution of left-handed circularly polarized (LCP) and right-handed circularly polarized (RCP) components propagating through single-core nonlinear chiral fiber. The analysis of modulation instability in nonlinear chiral fiber has been investigated starting from CCNLSEs. Based on a theoretical model and numerical simulations, the difference on the modulation instability gain spectrum in LCP and RCP components through chiral fiber has been analyzed by considering loss and chirality into account. The obtained simulation results have shown that the loss distorts the sidebands of the modulation instability gain spectrum, while chirality modulates the gain for LCP and RCP components in a different manner. This suggests that adjusting chirality strength may control the loss, and nonlinearity simultaneously provides stable modulated pulse propagation.

scholarly journals Determination of Absolute Structure of Chiral Crystals Using Three-Wave X-ray Diffraction

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1389
Author(s):  
Ksenia Kozlovskaya ◽  
Elena Ovchinnikova ◽  
Jun Kokubun ◽  
Andrei Rogalev ◽  
Fabrice Wilhelm ◽  
...  
Keyword(s):  
Bragg Reflection ◽  
Quantitative Description ◽  
X Rays ◽  
Circularly Polarized ◽  
X Ray ◽  
Left Handed ◽  
The Difference ◽  
The Right ◽  
Chiral Crystals ◽  
Absolute Structure

We propose a new method to determine the absolute structure of chiral crystals, which is based on the chiral asymmetry of multiple scattering diffraction. It manifests as a difference in the azimuthal dependence of the forbidden Bragg reflection intensity measured with left and right circularly polarized X-ray beams. Contrary to the existing ones, the suggested method does not use X-ray anomalous dispersion. The difference between the Renninger scans with circularly polarized X-rays has been experimentally demonstrated for the 001 reflection intensities in the right- and left-handed quartz single crystals. A Jmulti-based code on model-independent three-wave-diffraction approach has been developed for quantitative description of our experimental results. The proposed method can be applied to various structures including opaque, organic and monoatomic crystals, even with only light elements. To determine the type of isomer, the Renninger plot of a single forbidden reflection is sufficient.

scholarly journals Modified Dual-Band Stacked Circularly Polarized Microstrip Antenna

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Guo Liu ◽  
Liang Xu ◽  
Yi Wang
Keyword(s):  
Radiation Pattern ◽  
Global Positioning System ◽  
Microstrip Antenna ◽  
High Performance ◽  
Axial Ratio ◽  
Dual Band ◽  
Optimized Design ◽  
Positioning System ◽  
Circularly Polarized ◽  
Global Positioning

A novel high-performance circularly polarized (CP) antenna is proposed in this paper. Two separate antennas featuring the global positioning system (GPS) dual-band operation (1.575 GHz and 1.227 GHz for L1 band and L2 band, resp.) are integrated with good isolation. To enhance the gain at low angle, a new structure of patch and two parasitic metal elements are introduced. With the optimized design, good axial ratio and near-hemispherical radiation pattern are obtained.

scholarly journals Experimental tests for characterization of GPR antenna patterns

1994 ◽  
Vol 37 (5 Sup.) ◽  
Author(s):  
E. Pettinelli ◽  
N. Pierdicca ◽  
S. Piro ◽  
L. Versino
Keyword(s):  
Radiation Pattern ◽  
National Research Council ◽  
Experimental Tests ◽  
Radar Signal ◽  
Antenna Radiation ◽  
Buried Structures ◽  
Antenna Radiation Pattern ◽  
The Difference ◽  
Set Up

Detection and location of buried structures using the electromagnetic impulsive methodologies (GPR) require the study of the spatial distribution of energy irradiated by an antenna into the ground and the mechanisms of wave propagation and scattering from relevant targets. Evaluation of the difference in wave field distribution in the ground with respect to free space can provide some useful indications on the propagation of the Geo-radar signal in the ground and the spatial resolution capability of the GPR method. For this reason, a research group, involving “La Sapienza” University, Rome and the National Research Council began, during 1992, to perform studies on antenna radiation pattern, the propagation and scattering phenomena of GPR. This paper presents the experimental set up and the obtained results on the antenna radiation pattern.

scholarly journals A high-efficiency and ultrathin transmission-type circular polarization converter based on surface structure

2021 ◽  
Vol 8 ◽  
pp. 4
Author(s):  
Peng Xu ◽  
Wei Xiang Jiang ◽  
Xiao Cai ◽  
Yue Gou ◽  
Tie Jun Cui
Keyword(s):  
High Efficiency ◽  
Transmission Mode ◽  
Polarization Converter ◽  
Periodic Surface ◽  
Circularly Polarized ◽  
Left Handed ◽  
Via Holes ◽  
Working Frequency ◽  
The Right ◽  
Good Agreement

In this paper, we propose, design and fabricate a kind of ultrathin and high-efficiency circularly polarization converter based on artificially engineered surfaces in the transmission mode. The converter is composed of double-layer periodic surface structures with cross slots. The top and bottom layers are printed on both sides of the F4B substrate and connected by metallic via holes. The proposed converter can transform the right-handed circularly polarized incident electromagnetic (EM) wave to a left-handed circularly-polarized one with near-unity efficiency in the transmission mode, or vice versa. We explain the conversion mechanism based on numerical simulations and equivalent circuit (EC) theory. The measured result has a good agreement with the simulated one in the working frequency band. Such ultrathin polarization converters can be used in wireless microwave communication, remote sensing, and EM imaging where circularly polarization diversity is needed.

Vibration Analysis of Diesel’s Undercarriage by Virtual Measure and Actual Measure

2011 ◽  
Vol 228-229 ◽  
pp. 621-626
Author(s):  
Peng Liu ◽  
Ying Yun Huang ◽  
Hao Peng Gao ◽  
Da Sheng Ou
Keyword(s):  
Frequency Response ◽  
Time Domain ◽  
Vibration Analysis ◽  
Response Characteristics ◽  
Amplitude Frequency Response ◽  
Actual Measure ◽  
Frequency Response Characteristics ◽  
The Difference

This paper proposes to verify and test the vibration of diesel’s undercarriage got by virtual measure and actual measure through the analysis of time domain characteristics and amplitude frequency response characteristics of three-orientation vibrant speed of diesel’s undercarriage, represents the difference in time domain characteristics and amplitude frequency response characteristics got by virtual measure and actual measure, expounds the reasons of difference and puts forward a method to diminution the difference. It proves that virtual measure can replace actual measure in a way, though there are some difference in existence, we can erase these difference to the best of ours’ abilities through enough analysis.

Sign in / Sign up

Export Citation Format

Share Document