Design of perfect electrical conductor wall‐loaded 2.45 GHz high‐efficiency rectenna

2018 ◽  
Vol 29 (3) ◽  
pp. e21604 ◽  
Author(s):  
Gengqi Zheng ◽  
Kui Dang ◽  
Baohua Sun ◽  
Jincheng Zhang
Keyword(s):  
High Efficiency ◽  
Electrical Conductor ◽  
Perfect Electrical Conductor

scholarly journals On the Accuracy of Asymptotic Solutions for TM Waves Diffracting on an Impedance Wedge

2014 ◽  
Vol 2014 ◽  
pp. 1-5
Author(s):  
Sonia Fu ◽  
Pierre Jacolot ◽  
Tommaso Balercia ◽  
Christian Rom ◽  
Jørgen B. Andersen ◽  
...  
Keyword(s):  
Electromagnetic Field ◽  
Boundary Conditions ◽  
The Other ◽  
Asymptotic Solutions ◽  
Electrical Conductor ◽  
Impedance Wedge ◽  
Uniform Theory Of Diffraction ◽  
Approximate Boundary Conditions ◽  
Perfect Electrical Conductor

The contribution focuses on the accuracy of two asymptotic solutions aimed at representing the electromagnetic field scattered by penetrable wedges. One is a heuristic manipulation of the solution for the perfect electrical conductor, and the other one is a more rigorous coefficient based on approximate boundary conditions. The results presented here extend those proposed by other authors by illustrating the accuracy of such solutions at the edge of validity of the uniform theory of diffraction. In particular, they show that the heuristic formulation can be freely applied in similar conditions, while the other might not always lead to accurate predictions.

scholarly journals Reshaping the perfect electrical conductor cylinder arbitrarily

2008 ◽  
Vol 10 (11) ◽  
pp. 113016 ◽  
Author(s):  
Huanyang Chen ◽  
Xiaohe Zhang ◽  
Xudong Luo ◽  
Hongru Ma ◽  
Che Ting Chan
Keyword(s):  
Electrical Conductor ◽  
Perfect Electrical Conductor

1D and 2D phase gradient perforated dielectric reflective surfaces atmmWave

2017 ◽  
Vol 10 (4) ◽  
pp. 446-452 ◽  
Author(s):  
Mustafa K. Taher Al-Nuaimi ◽  
Wei Hong ◽  
Xiqi Gao
Keyword(s):  
Electromagnetic Waves ◽  
Normal Incidence ◽  
Electrical Conductor ◽  
Wave Regime ◽  
Phase Gradient ◽  
Reflected Waves ◽  
Dielectric Surfaces ◽  
Full Wave ◽  
Perfect Electrical Conductor ◽  
Reflective Surfaces

This paper presents the design of all dielectric non-absorptive phase gradient reflective surfaces that can be used to manipulate the reflected electromagnetic waves at millimeter-wave regime. Compared with a bare perfect electrical conductor reflector which obeys the classical Snell's law of reflection, the presented design can effectively alter both the shape and level of the backscattered energy and thus radar cross section (RCS) reduction is achieved in the specular direction. One- and two-dimensional phase gradient reflective dielectric surfaces of phase change about 72° across their apertures are designed and their ability to manipulate the reflected waves under normal incidence are investigated both by means of full-wave simulations and experimentally tested for validation. More than 6 dB of specular RCS reduction is achieved from about 66.5–78.2 GHz.

HELMHOLTZ INSTABILITY OF A VISCOUS COMPRESSIBLE PLASMA

1965 ◽  
Vol 43 (10) ◽  
pp. 1891-1903
Author(s):  
O. P. Bhutani ◽  
A. K. Sundaram
Keyword(s):  
Uniform Magnetic Field ◽  
Plane Boundary ◽  
Electrical Conductor ◽  
Helmholtz Instability ◽  
Compressible Plasma ◽  
Viscosity Parameter ◽  
Perfect Electrical Conductor ◽  
The Stability ◽  
Exchange Of Stability ◽  
Mode Technique

An attempt has been made to discuss the Helmholtz instability of a viscous compressible plasma considered to be a perfect electrical conductor. Initially, the plasma is assumed to be in contact with a uniform magnetic field along a plane boundary that is parallel to the field and is assumed to flow with uniform velocity V0 perpendicular to the field. By using the normal mode technique, the amplitudes of the perturbed quantities are obtained. The conditions for the validity of the principle of exchange of stability and overstability are obtained also. Finally, the growth-rate curves for different values of the viscosity parameter λ′ have been drawn and it has been found that the effect of viscosity adds to the stability of the system.

scholarly journals Low Radar Cross-section and Low Cost Dipole Antenna Reflector

2017 ◽  
Vol 6 (3) ◽  
pp. 25 ◽  
Author(s):  
G. G. Machado ◽  
M. T. De Melo ◽  
H. V. H. Silva Filho ◽  
A. G. Neto ◽  
T. R. De Souza
Keyword(s):  
Laboratory Experiment ◽  
Cross Section ◽  
Return Loss ◽  
Low Cost ◽  
Frequency Selective Surface ◽  
Dipole Antenna ◽  
Electrical Conductor ◽  
Perfect Electrical Conductor ◽  
Antenna Reflector ◽  
Good Agreement

This paper presents a method for reducing Radar CrossSection (RCS) of an increased gain metal backed dipole antenna. Numerical simulations were done and compared to a laboratory experiment. The results show that when a Perfect Electrical Conductor (PEC) is replaced by a Frequency Selective Surface (FSS), the antenna is still able to perform with the desired characteristics, but the RCS of the structure is greatly reduced out of band. The design of the FSS and the return loss, gain improvement, and RCS are presented for an antenna operating at 4.2GHz, and the results are compared with a conventional metal backed layout. Measurements show a good agreement with the simulations, and so the advantages on other structures from the reviewed literature are mentioned.

Microcalorimeters for X-Ray Spectroscopy

1988 ◽  
Vol 102 ◽  
pp. 41
Author(s):  
E. Silver ◽  
C. Hailey ◽  
S. Labov ◽  
N. Madden ◽  
D. Landis ◽  
...  
Keyword(s):  
High Resolution ◽  
High Efficiency ◽  
Thermal Response ◽  
Low Noise ◽  
High Resolution Spectroscopy ◽  
Superconducting Transition ◽  
Sapphire Substrates ◽  
Laboratory Plasmas ◽  
Adiabatic Demagnetization ◽  
Theoretical Predictions

The merits of microcalorimetry below 1°K for high resolution spectroscopy has become widely recognized on theoretical grounds. By combining the high efficiency, broadband spectral sensitivity of traditional photoelectric detectors with the high resolution capabilities characteristic of dispersive spectrometers, the microcalorimeter could potentially revolutionize spectroscopic measurements of astrophysical and laboratory plasmas. In actuality, however, the performance of prototype instruments has fallen short of theoretical predictions and practical detectors are still unavailable for use as laboratory and space-based instruments. These issues are currently being addressed by the new collaborative initiative between LLNL, LBL, U.C.I., U.C.B., and U.C.D.. Microcalorimeters of various types are being developed and tested at temperatures of 1.4, 0.3, and 0.1°K. These include monolithic devices made from NTD Germanium and composite configurations using sapphire substrates with temperature sensors fabricated from NTD Germanium, evaporative films of Germanium-Gold alloy, or material with superconducting transition edges. A new approache to low noise pulse counting electronics has been developed that allows the ultimate speed of the device to be determined solely by the detector thermal response and geometry. Our laboratory studies of the thermal and resistive properties of these and other candidate materials should enable us to characterize the pulse shape and subsequently predict the ultimate performance. We are building a compact adiabatic demagnetization refrigerator for conveniently reaching 0.1°K in the laboratory and for use in future satellite-borne missions. A description of this instrument together with results from our most recent experiments will be presented.

Imaging and diffraction modes in Scanning Transmission Electron Microscopy

1986 ◽  
Vol 44 ◽  
pp. 684-687
Author(s):  
J. M. Cowley ◽  
R. Glaisher ◽  
J. A. Lin ◽  
H.-J. Ou
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
High Efficiency ◽  
Fiber Optic ◽  
Image Intensifier ◽  
Detector System ◽  
Detector Plane ◽  
Secondary Electrons ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Special Detector

Some of the most important applications of STEM depend on the variety of imaging and diffraction made possible by the versatility of the detector system and the serial nature, of the image acquisition. A special detector system, previously described, has been added to our STEM instrument to allow us to take full advantage of this versatility. In this, the diffraction pattern in the detector plane may be formed on either of two phosphor screens, one with P47 (very fast) phosphor and the other with P20 (high efficiency) phosphor. The light from the phosphor is conveyed through a fiber-optic rod to an image intensifier and TV system and may be photographed, recorded on videotape, or stored digitally on a frame store. The P47 screen has a hole through it to allow electrons to enter a Gatan EELS spectrometer. Recently a modified SEM detector has been added so that high resolution (10Å) imaging with secondary electrons may be used in conjunction with other modes.

Influence of MBE Growth Conditions on Dislocation Densities of GaAs/Ge Epilayers Grown on Silicon Substrates

1985 ◽  
Vol 43 ◽  
pp. 364-365
Author(s):  
K.M. Hones ◽  
P. Sheldon ◽  
B.G. Yacobi ◽  
A. Mason
Keyword(s):  
High Efficiency ◽  
Lattice Mismatch ◽  
Low Cost ◽  
Growth Conditions ◽  
Nonradiative Recombination ◽  
Device Structure ◽  
Si Substrates ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Dislocation Type

There is increasing interest in growing epitaxial GaAs on Si substrates. Such a device structure would allow low-cost substrates to be used for high-efficiency cascade- junction solar cells. However, high-defect densities may result from the large lattice mismatch (∼4%) between the GaAs epilayer and the silicon substrate. These defects can act as nonradiative recombination centers that can degrade the optical and electrical properties of the epitaxially grown GaAs. For this reason, it is important to optimize epilayer growth conditions in order to minimize resulting dislocation densities. The purpose of this paper is to provide an indication of the quality of the epitaxially grown GaAs layers by using transmission electron microscopy (TEM) to examine dislocation type and density as a function of various growth conditions. In this study an intermediate Ge layer was used to avoid nucleation difficulties observed for GaAs growth directly on Si substrates. GaAs/Ge epilayers were grown by molecular beam epitaxy (MBE) on Si substrates in a manner similar to that described previously.

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