Effects of Atomic Oxygen and UV rays ageing on the Reflection Coefficient of Carbon/Carbon Plates in the 12–18 GHz Frequency Range

2021 ◽  
Author(s):  
Andrea Delfini ◽  
Roberto Pastore ◽  
Fabio Santoni ◽  
Mario Marchetti
Keyword(s):  
Reflection Coefficient ◽  
Atomic Oxygen ◽  
Frequency Range ◽  
Uv Rays

scholarly journals Design and Development of a Wideband Planar Yagi Antenna Using Tightly Coupled Directive Element

Micromachines ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 975
Author(s):  
Muhammad A. Ashraf ◽  
Khalid Jamil ◽  
Ahmed Telba ◽  
Mohammed A. Alzabidi ◽  
Abdel Razik Sebak
Keyword(s):  
Reflection Coefficient ◽  
Wireless Communication ◽  
Radiation Pattern ◽  
Excellent Agreement ◽  
Frequency Range ◽  
Fractional Bandwidth ◽  
Yagi Antenna ◽  
Tightly Coupled ◽  
Simulation Results ◽  
Novel Concept

In this paper, a novel concept on the design of a broadband printed Yagi antenna for S-band wireless communication applications is presented. The proposed antenna exhibits a wide bandwidth (more than 48% fractional bandwidth) operating in the frequency range 2.6 GHz–4.3 GHz. This is achieved by employing an elliptically shaped coupled-directive element, which is wider compared with other elements. Compared with the conventional printed Yagi design, the tightly coupled directive element is placed very close (0.019λ to 0.0299λ) to the microstrip-fed dipole arms. The gain performance is enhanced by placing four additional elliptically shaped directive elements towards the electromagnetic field’s direction of propagation. The overall size of the proposed antenna is 60 mm × 140 mm × 1.6 mm. The proposed antenna is fabricated and its characteristics, such as reflection coefficient, radiation pattern, and gain, are compared with simulation results. Excellent agreement between measured and simulation results is observed.

scholarly journals Influence of water content of expanded clay on the reflection coefficient of electromagnetic shild

2021 ◽  
Vol 66 (1) ◽  
pp. 93-100
Author(s):  
T. V. Borbot’ko ◽  
S. E. Savanovich
Keyword(s):  
Reflection Coefficient ◽  
Moisture Content ◽  
Electromagnetic Radiation ◽  
Pore Size ◽  
Operating Frequency ◽  
Reflection Coefficients ◽  
Frequency Range ◽  
Operating Frequency Range ◽  
Influence Of Water ◽  
The Relationship

The regularities of the influence of the moisture content of expanded clay on the values of the reflection coefficient of electromagnetic radiation (EMR) of this material in the frequency range of 1–17 GHz have been established. The relationship between the size of fractions (pore size) of expanded clay and the operating frequency range of the EMR screen samples has been determined. It is shown that a twofold increase in the moisture content of expanded clay with fractions of 1…4 and 10…20 mm provides an extension of the operating frequency range of the EMR shield samples made on the basis of this material, with a decrease in the reflection coefficient of the test samples by 1.7 and 3 times, respectively. It was found that an increase in the moisture content of expanded clay from 19 to 40 % with a decrease in the size of its fractions from 10…20 to 1…4 mm and a pore size from 0.1…0.2 to 0.01…0.06 mm provides a decrease in the values of the reflection coefficient of EMR screen samples at frequencies of 7.7–17.0 GHz, and an increase in the size of expanded clay fractions from 1…4 to 10…20 mm with an increase in the size of its pores from 0.01…0.06 to 0.1…0.2 mm provides a decrease in the values of the reflection coefficient of EMR screen samples at frequencies of 1.0–7.7 GHz. It is shown that the practical use of these regularities makes it possible to form EMR screen samples with reflection coefficients from –2.8 to –22.0 dB in the frequency range 1–17 GHz, which makes it possible to recommend them for use when creating shielded rooms.

The measurement of reflection coefficient dispersion in the ultrasonic frequency range

2019 ◽  
Author(s):  
Min Li ◽  
Genyang Tang ◽  
Chunhui Dong ◽  
Liming Zhao ◽  
Chao Sun ◽  
...  
Keyword(s):  
Reflection Coefficient ◽  
Ultrasonic Frequency ◽  
Frequency Range

Shielded open-circuited probe for in-situ measurements of soil permittivity in Very high frequency (VHF) and Ultra high frequency (UHF) bands

2021 ◽  
pp. 014233122110377
Author(s):  
Konstantin Muzalevskiy ◽  
Andrey Karavaysky
Keyword(s):  
Reflection Coefficient ◽  
Root Mean Square Error ◽  
Mean Square Error ◽  
Root Mean Square ◽  
High Frequency ◽  
Mean Square ◽  
Frequency Range ◽  
Frequency Spectra ◽  
Determination Coefficient ◽  
Error Determination

In this paper, the shielded open-circuited probe operating in the wide frequency range from 75MHz to 2GHz is proposed. The probe is made of an SubMiniature version A (SMA) flange connector. The central rod of the SMA connector emerges from a coaxial transition in the flange and shielded by four rods. The robe design allows us to calculate of the probe reflection coefficient S11 used simple analytical transmission line model (TEM wave mode), the parameters of which were calibrated on a set of substances with a known frequency spectrum of permittivity. The refractive index (RI) and normalized attenuation coefficient (NAC) retrieval technique is based on solving the inverse problem of minimizing the residual norm between measured and calculated frequency spectra of reflection coefficient S11. After calibration, the root-mean-square error (determination coefficient) between the measured and calculated module and phase of the reflection coefficient S11 for the sets of calibration media air, distilled water, butanol, pure ice, water solution with NaCl of salinity of 8.9% do not exceed 0.26dB (0.995) and 0.03 rad (0.999), respectively, in the frequency range from 75MHz to 2GHz. The root-mean-square error (determination coefficient) between the measured RI and NAC spectra for four soil cover samples (variation of the clay fraction from 10.5 g/g to 47.6 g/g) using the proposed probe and a precision coaxial cell not exceeds 0.109 (0.993) and 0.057 (0.986), respectively, in the frequency range from 75 MHz to 2 GHz. As a result, it is experimentally shown that RI и NAC can be measured by the proposed non-precision probe with an error comparable to the precision coaxial cell.

scholarly journals Dual-Band Patch Antenna Fed by Meandering Probe for Low Cross-Polarization

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Xiao-Lan Zhao ◽  
Quan Wei Lin
Keyword(s):  
Reflection Coefficient ◽  
Patch Antenna ◽  
Dual Band ◽  
Cross Polarization ◽  
Frequency Range ◽  
Face To Face ◽  
Resonance Modes ◽  
The Cross ◽  
Polarization Level

This paper presents a dual-band patch antenna loaded with face-to-face U-shaped slots fed by a substrate-integrated meandering probe (SIM-probe). With the presence of U-shaped slots, two current paths are formed, which leads to the resonance modes at 2.4 and 3.65 GHz on the patch. The SIM-probe suppresses the unwanted cross-polarization radiations by providing out-of-phase vertical currents from vertical metallic vias. To verify our work, a prototype was fabricated and tested. The proposed antenna achieves the impedance bandwidths of 9.4% and 9% from the frequency range of 2.34–2.57 GHz and 3.5–3.83 GHz (for the reflection coefficient ≤ −10 dB) and obtains average gains of 5.8 dBi and 6.8 dBi at both bands. The cross-polarization level is below −20 dB. Measured results agree well with the simulation.

scholarly journals Compact Wideband Broadside-Coupled Microstrip-Slot Bandpass Filter for Communication Applications

2017 ◽  
Vol 5 (3) ◽  
pp. 650
Author(s):  
Norhudah Seman ◽  
Dyg Norkhairunisa Abang Zaidel ◽  
Zuhaili Amalina Abd. Wahid ◽  
Nor Azimah Mohd Shukor ◽  
Tharek Abd Rahman
Keyword(s):  
Reflection Coefficient ◽  
Insertion Loss ◽  
Bandpass Filter ◽  
Frequency Range ◽  
Compact Size ◽  
Low Insertion Loss ◽  
5 Ghz ◽  
Side Coupling

<p>This paper proposes a compact size design of wideband bandpass filter (BPF). The broad-side coupling microstrip-slot technique is used to accomplish a good passband response with very low insertion loss across a wideband frequency range. The BPF that is designed using Rogers RO4003C substrate shows a good performance with the respective maximum reflection coefficient and insertion loss of -10 dB and 1.2 dB between 0.92 GHz and 5 GHz. This type of BPF filter is useful in any communication applications.</p>

scholarly journals Гигантский магниторезистивный эффект в отражении микроволн от сверхрешеток (CoFe)/Cu

2021 ◽  
Vol 91 (2) ◽  
pp. 308
Author(s):  
А.Б. Ринкевич ◽  
Е.А. Кузнецов ◽  
Д.В. Перов ◽  
М.А. Миляев
Keyword(s):  
Magnetic Field ◽  
Reflection Coefficient ◽  
Field Dependence ◽  
Giant Magnetoresistance ◽  
Magnetic Field Dependence ◽  
Wave Reflection ◽  
Frequency Range ◽  
Giant Magnetoresistive Effect ◽  
The Magnetic Field ◽  
Magnetoresistive Effect

Experimental study of microwave giant magnetoresistive effect in wave reflection has been carried out in frequency range from 26 to 38 GHz. The magnitude of the effect is obtained and its magnetic field dependence is defined. The experiments are carried out with (CoFe)/Cu superlattices, which have giant magnetoresistance. Calculations of the magnetic field dependence of microwave reflection coefficient are fulfilled. The measured values of reflection coefficient variations are found to be greater than the calculated ones. This difference is connected with approximation within which the superlattice is replaced by the uniform metallic plate in calculations. A frequency dependence of microwave giant magnetoresistive effect in reflection is also observed. This dependence is explained by the influence of the waveguide impedance where the sample is placed in measurements.

scholarly journals The Improvement of first Iteration Log Periodic Fractal Koch Antenna with Slot Implementation

2018 ◽  
Vol 8 (4) ◽  
pp. 2564
Author(s):  
N. S. M. Yaziz ◽  
M. K. A. Rahim ◽  
F. Zubir ◽  
N. S. Nadzir ◽  
R. Dewan ◽  
...  
Keyword(s):  
Reflection Coefficient ◽  
Radiation Pattern ◽  
Digital Television ◽  
Frequency Range ◽  
Operating Bandwidth ◽  
Good Agreement

<span>In this paper, a slotted is introduced at each of the radiating elements on the 1<sup>st</sup> iteration log periodic fractal Koch antenna (LPFKA). The antenna is designed to testify the appropriate performance at UHF Digital television which operates from 4.0 GHz to 1.0 GHz. The dimension of the conventional 0<sup>th</sup> iteration LPKFA is successfully reduced by 17% with the implementation of slotted. The results show a good agreement with a stable radiation pattern across the operating bandwidth, stable gain more than 5 dBi and reflection coefficient of below -10 dB over the desired frequency range.</span>

scholarly journals Improved Microstrip Antenna with HIS Elements and FSS Superstrate for 2.4 GHz Band Applications

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Praphat Arnmanee ◽  
Chuwong Phongcharoenpanich
Keyword(s):  
Reflection Coefficient ◽  
Microstrip Antenna ◽  
Frequency Selective Surface ◽  
Antenna Design ◽  
Antenna Gain ◽  
Frequency Range ◽  
Electromagnetic Band Gap ◽  
High Impedance ◽  
Integrated Antenna ◽  
High Impedance Surface

This research presents a microstrip antenna integrated with the high-impedance surface (HIS) elements and the modified frequency selective surface (FSS) superstrate for 2.4 GHz band applications. The electromagnetic band gap (EBG) structure was utilized in the fabrication of both the HIS and FSS structures. An FR-4 substrate with 120 mm × 120 mm × 0.8 mm in dimension (W × L × T) and a dielectric constant of 4.3 was used in the antenna design. In the antenna development, the HIS elemental structure was mounted onto the antenna substrate around the radiation patch to suppress the surface wave, and the modified FSS superstrate was suspended 20 mm above the radiating patch to improve the directivity. Simulations were carried out to determine the optimal dimensions of the components and the antenna prototype subsequently fabricated and tested. The simulation and measured results were agreeable. The experimental results revealed that the proposed integrated antenna (i.e., the microstrip antenna with the HIS and FSS structures) outperformed the conventional microstrip antenna with regard to reflection coefficient, the radiation pattern, gain, and radiation efficiency. Specifically, the proposed antenna could achieve the measured antenna gain of 10.14 dBi at 2.45 GHz and the reflection coefficient of less than −10 dB and was operable in the 2.39–2.51 GHz frequency range.

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