scholarly journals Wideband Circularly Polarized Antenna Based on a Non-Uniform Metasurface

2020 ◽  
Vol 10 (23) ◽  
pp. 8652
Author(s):  
Tuan Tu Le ◽  
Huy Hung Tran ◽  
Ayman Abdulhadi Althuwayb
Keyword(s):  
High Frequency ◽  
Frequency Region ◽  
The Other ◽  
Impedance Bandwidth ◽  
High Frequency Region ◽  
Circularly Polarized ◽  
Operation Characteristic ◽  
Operating Bandwidth ◽  
Overall Performance ◽  
Comparable Size

This paper presents a non-uniform metasurface (MS)-based circularly polarized (CP) antenna that is able to perform with a wideband operation characteristic. A squared patch with truncated corners was chosen as a radiating CP source. Then, unlike the conventional CP MS antennas with a uniform MS, the proposed design employed a non-uniform MS placed above the driven patch. Apart from increasing the impedance bandwidth, the non-uniform MS was also capable of generating two additional CP bands in the high-frequency region, which contributed to significantly increasing the antenna’s overall performance. For demonstration, an antenna prototype was fabricated and experimentally tested. The measured operating bandwidth of the fabricated antenna was about 30% and the broadside gain within this band was around 6.6 dBic. Compared to the other reported CP MS antennas in the open literature, the proposed design has the advantages of very wideband operation with a comparable size and gain.

Anderson-Stuart Model to Analyze AC and DC Conductivity of Lithium Zinc-Silicate Glass / Glass-Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 919-924
Author(s):  
M.S. Jogad ◽  
V.K. Shrikhande ◽  
A.H. Dyama ◽  
L.A. Udachan ◽  
Govind P. Kothiyal
Keyword(s):  
High Frequency ◽  
Glass Ceramics ◽  
Low Frequency ◽  
Frequency Region ◽  
Dc Conductivity ◽  
Frequency Range ◽  
High Frequency Region ◽  
Dc Conductivities ◽  
Conductivity Variation ◽  
Different Temperatures

AC and DC conductivities have been measured by using the real (e¢) and imaginary (e¢¢) parts of the dielectric constant data of glass and glass-ceramics (GC) at different temperatures in the rage 297-642K and in the frequency range 100 Hz to 10 MHz. Using Anderson –Stuart model, we have calculated the activation energy, which is observed to be lower than that of the DC conductivity. The analysis for glass/glass-ceramics indicates that the conductivity variation with frequency exhibits an initial linear region followed by nonlinear region with a maximum in the high-frequency region. The observed frequency dependence of ionic conductivity has been analyzed within the extended Anderson–Stuart model considering both the electrostatic and elastic strain terms. In glass/glassceramic the calculations based on the Anderson-Stuart model agree with the experimental observations in the low frequency region but at higher frequencies there is departure from measured data.

Channel thermal noise of SOI MOSFET in high-frequency region

2005 ◽  
Vol 20 (2) ◽  
pp. 216-220
Author(s):  
Nirupama Kapoor ◽  
Subhasis Haldar ◽  
Mridula Gupta ◽  
R S Gupta
Keyword(s):  
High Frequency ◽  
Thermal Noise ◽  
Frequency Region ◽  
High Frequency Region ◽  
Soi Mosfet

Further Observations on Noise Levels in Infant Incubators

PEDIATRICS ◽  
1979 ◽  
Vol 63 (1) ◽  
pp. 100-106 ◽  
Author(s):  
Fred H. Bess ◽  
Barbara Finlayson Peek ◽  
Judy J. Chapman
Keyword(s):  
High Frequency ◽  
Impulse Noise ◽  
Life Support ◽  
Acoustic Analysis ◽  
Frequency Region ◽  
Noise Levels ◽  
Storage Unit ◽  
High Frequency Region ◽  
Different Types ◽  
Opening And Closing

The purpose of this study was to conduct an acoustic analysis of incubator noise under two conditions: when the incubator was associated with different types of life-support equipment; and when impulse noise was created by striking the side of the incubator or by opening and closing the doors of the storage unit. It was found that the life-support equipment increased the overall noise levels of incubators by as much as 15 to 20 dB. Much of this increased energy was in the high frequency region. Impulse signals created by striking the side of the incubator ranged from 130 to 140 dB. A representative impulse for opening the incubator was 92.8 dB, whereas closing the door produced a peak amplitude of 114 dB.

Carrier-envelope-phase effect on laser-driven bound-bound transitions in the high-frequency region

2012 ◽  
Vol 86 (4) ◽  
Author(s):  
Zhen Zhai ◽  
Dian Peng ◽  
Xi Zhao ◽  
Fuming Guo ◽  
Yujun Yang ◽  
...  
Keyword(s):  
High Frequency ◽  
Frequency Region ◽  
Phase Effect ◽  
High Frequency Region ◽  
Carrier Envelope Phase

New data on the kaolinite-potassium acetate complex

Clay Minerals ◽  
1999 ◽  
Vol 34 (4) ◽  
pp. 565-577 ◽  
Author(s):  
M. D. Ruiz Cruz ◽  
F. I. Franco Duro
Keyword(s):  
High Frequency ◽  
Electrostatic Interactions ◽  
Potassium Acetate ◽  
Frequency Region ◽  
Basal Spacing ◽  
Intercalation Complex ◽  
High Frequency Region ◽  
Oh Groups ◽  
Acetate Complex ◽  
Inner Surface

AbstractThe intercalation complex of kaolinite and potassium acetate (KAc) was studied by HTXRD, IR spectroscopy and DTA-TG. The HTXRD patterns indicate that the 14.06 Å basal spacing of the complex contracts to 11.77 Å and 9.35 Å after heating at 60°C. The DTA-TG data indicate that water is present in these new complexes, the decomposition of which occurs between 290°C and 400°C. Modifications observed in the high-frequency region of the spectra obtained after heating suggest that K ions occupy the ditrigonal holes in the OH surface of the kaolinite layers, whereas water is probably located between the KAc layer and the OH surface of the kaolinite. This structural arrangement would favour the H-bonding between inner-surface OH groups and water and justifies the presence of new bands at lower frequencies. Electrostatic interactions between the keyed K ions and O of the inner OH groups would justify the modifications of the 3619 cm-1 OH-stretching band.

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