KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Search Results

Now showing 1 - 8 of 8

Some of the metrics are blocked by your
consent settings
A thz metamaterial absorber with multiple polarization: Insensitive, sensitive, and tunable
(2021-01-01)
Mohanty, Ayesha
;
Acharya, Om Prakash
;
Appasani, Bhargav
;
Sooksood, Kriangkrai
;
Mohapatra, Sushanta Kumar
Terahertz (THz) absorbers are gaining interest in many applications. In this paper, we present the design and simulation of a multiband metama-terial absorber (MMA) with combined polarization properties and prominent absorption at 2.2 THz and 3.9 THz. The MMA comprises two square split-ring resonators and one square ring resonator placed on top of a polyimide dielectric spacer, offering multiband absorption characteristics with maximum absorptivity of 93.18% and 96.09%, respectively. The most protruding feature of this design is that it displays multiple polarization characteristics, including insensitivity, sensitivity, and tunability, even though the structure is similar to those of conventional absorbers. Firstly, the distinctly visible absorption spectra at 1.8 THz, gradually diminishes with an increase in polarization angle and then completely vanishes for TM polarization. Secondly, the prominent band at 2.2 THz is insensitive to changes in polarization of the incident wave, whereas, at 3.9 THz, the absorption band displays polarization tunability characteristics. Due to the multiple characteristics displayed by the structure, this MMA can be simultaneously used for several applications in the terahertz frequency regime such as imaging, terahertz spectroscopy, sensing, and stealth technology.
Some of the metrics are blocked by your
consent settings
Effects of H2O2 and temperature on electrolytic pickling of austenitic stainless steel 304L in Na2SO4 solution
(2020-10-01)
Tipves, Kanrayaphus
;
Lothongkum, Gobboon
;
Lothongkum, Anchaleeporn Waritswat
The effects of H2O2 solution addition and temperature on electrolytic pickling via Na2SO4 solution to eliminate the metal oxide layers of an annealed 304L stainless steel were investigated by polarization technique. The experimental conditions involved a pure 190 kg × m-3 Na2SO4 solution and a mixture of 190 kg × m-3 Na2SO4 + 10 kg × m-3 H2O2 at 298, 318 and 333 K and pH 4. It was found that the addition of a 10 kg × m-3 H2O2 solution in 190 kg × m-3 Na2SO4 solution and an increase in temperature resulted in a decrease in the passive region of the polarization curves. The results from the SEM images, the XRD patterns and root-meansquare roughness showed that the surface of the annealed 304L stainless steel was smoother and fewer remaining oxide scales was found when pickling in 190 kg × m-3 Na2SO4 + 10 kg × m-3 H2O2 solution. However, no effects of the addition of 10 kg × m-3 H2O2 solution in 190 kg × m-3 Na2SO4 solution and temperature on pickling time at 298, 318 and 333 K were observed.
Some of the metrics are blocked by your
consent settings
Polarization effect of quantitative phase imaging using digital holography method
(2019-01-01)
Gasosoth, T.
;
Jongjinakool, K.
;
Buranasiri, P.
In this study, we investigate polarization effect of quantitative phase imaging (QPI) using digital holography (DH) technique. By using different polarization state of writing beam the reconstructed images of different kinds of samples including biological cells from DH interferometer have been analyzed and shown their difference of quantitative measurement with reconstructed images of unpolarized writing fields. In addition, the property changes of some samples have been studied using the property analysis of the polarization image fields.
Some of the metrics are blocked by your
consent settings
Polarization reconfigurable suspended antenna using RF switches and P-I-N diodes
(2014-01-01)
Boonying, Komkris
;
Phongcharoenpanich, Chuwong
;
Kosulvit, Sompol
Polarization reconfigurable square flat antenna using RF switches and P-I-N diodes is presented for WLAN application operated at the center frequency of 2.45 GHz. The proposed antenna consists of the square flat structure, three switches (six P-I-N diodes), transmission-line phase shifters of 0 and 90 degrees. The antenna can be switched between 5 different states: vertical, horizontal and slant polarizations for linear polarization (LP), left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP) by controlling the DC bias of 5 V and the current of 16 mA for the P-I-N diodes. The simulated and measured results show that the proposed antenna can cover the impedance bandwidth from 2.400 GHz to 2.484 GHz and good axial ratio for the circular polarization. © 2014 IEEE.
Some of the metrics are blocked by your
consent settings
Polymer film selection for corrosion protection of data storage magnetic materials
(2011-12-01)
Chatruprachewin, Santi
;
Supadee, Laddawan
;
Titiroongruang, Wisut
Due to the current requirement of high recording density of hard disk drive, the thickness of DLC layer which is the protective layer is needed to be reduced. Therefore, the corrosion of read-write elements that are fabricated from soft magnetic materials is more critical. During the photolithography process, polymer photoresist is playing the major role on controlling the corrosion of soft magnetic materials. Two different types of polymer photoresists are selected to investigate, noted as wet photoresist and dry photoresist, respectively. Contact angle measurement, AFM and SEM are techniques using to determine the quality of polymer photoresists. Furthermore, the direct corrosion is also studied by using potentiostat/galvanostat-based measurements. The result suggested that the wet photoresist, AZ4999 Clariant, is better as compared to that of dry photoresist. No surface degradation as well as surface defects of the wet photoresist was found after lithography process. The corrosion rate of the specimen coated by this corresponding wet film is found to be only 1.44×10 <sup>-6</sup> mm/y. In addition, the wet photoresist surface is hydrophobic posed of more than 75 degree of contact angle. Copyright © 2011 American Scientific Publishers All rights reserved.
Some of the metrics are blocked by your
consent settings
A probe-fed U-shaped cross-sectional antenna with tuning stubs on a U-shaped ground plane
(2006-01-01)
Srimoon, Duang Arthit
;
Phongcharoenpanich, Chuwong
;
Krairiksh, Monai
A probe-fed U-shaped cross-sectional antenna with tuning stubs on a U-shaped ground plane is proposed for wideband applications. The bottom of the antenna is etched to form tuning stubs for impedance matching. The simulated results of return loss, co- and cross-polarized patterns are presented and compared with the measured ones. Characteristics of a constructed antenna prototype at the operating frequency show that the antenna has an impedance bandwidth (2:1 VSWR) of 37.44% and average gain level of 8.5 dBi. Good radiation characteristics of the proposed antenna have been obtained that is the cross-polarization level and front-to-back ratio in both E- and H-planes across the large bandwidth are better than 22 dB and 12 dB, respectively. Copyright © 2006 The Institute of Electronics, Information and Communication Engineers.
Some of the metrics are blocked by your
consent settings
Analysis of a circumferential aperture beside the radial waveguide near the reflector
(2003-01-01)
Kruekaew, B.
;
Phongcharoenpanich, C.
This paper presents the analysis and design of a simple conical beam antenna using circumferential aperture beside the radial waveguide near the reflector for vertically polarized radiation. The structure of the antenna is composed of two circular plates that are parallelled to each other in horizontal plane. The vector potential approach is used to calculate the radiation properties. The radiation characteristics such as radiation pattern, elevation beam peak, half power beamwidth and maximum directivity of the antenna are analyzed. The contour plot of elevation beam peak and directivity as a function of the radius of the circular plates and the spacing between the radial waveguide and the reflector are illustrated as the guideline for the design criterion of a conical beam antenna using circumferential aperture beside the radial waveguide near the reflector for vertically polarized.
Some of the metrics are blocked by your
consent settings
Radiation characteristics of inclined slot antenna on conducting spherical cavity
(2003-01-01)
Phongcharoenpanich, C.
;
Boonrod, D.
;
Krairiksh, M.
This paper presents theoretical investigations of the characteristics such as radiation pattern, half-power beamwidth, directivity, front-to-back ratio and polarization of an inclined slot on spherical surface. The total fields inside the cavity are formulated by means of the combination of TE and TM modes. The unknown coefficients of the fields are determined by imposing the boundary conditions. The voltage distribution along the slot is reasonably assumed to be the sinusoidal functions. The numerical results of radiation characteristics for various radii of the spherical surface are illustrated. The comparisons between horizontal slot and inclined slot are reported. The result of the analysis shows that this technique is very useful for the design of spherical slot array antenna of any orientation.

KMITL

Browse

Filters

Settings

Sort By

Results per page

Search Results