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    Omnidirectional anti-reflection properties of vertically align SiO2 nanorod films prepared by electron beam evaporation with glancing angle deposition
    (2018-01-01)
    Prachachet, R.
    ;
    Samransuksamer, B.
    ;
    Horprathum, M.
    ;
    Eiamchai, P.
    ;
    Limwichean, S.
    Omnidirectional anti-reflection coating nanostructure film have attracted enormous attention for the developments of the optical coating, lenses, light emitting diode, display and photovoltaic. However, fabricated of the omnidirectional antireflection nanostructure film on glass substrate in large area was a challenge topic. In the past two decades, the invention of glancing angle deposition technique as a growth of well-controlled two and three-dimensional morphologies has gained significant attention because of it is simple, fast, cost-effective and high mass production capability. In this present work, the omnidirectional anti-reflection nanostructure coating namely silicon dioxide (SiO<inf>2</inf>) nanorods has been investigated for optimized high transparent layer at all light incident angle. The SiO<inf>2</inf> nanorod films of an optimally low refractive index have been fabricated by electron beam evaporation with the glancing angle deposition technique. The morphological of the prepared sampled were characterized by field-emission scanning electron microscope (FE-SEM) and high-resolution transmission electron microscope (HRTEM). The optical transmission and omnidirectional property of the SiO<inf>2</inf> nanorod films were investigated by UV-Vis-NIR spectrophotometer. The measurement were performed at normal incident angle and a full spectral range of 200 - 2000 nm. The angle dependent transmission measure were investigated by rotating the specimen, with incidence angle defined relative to the surface normal of the prepared samples. The morphological characterization results showed that when the glancing angle deposition technique was applied, the vertically align SiO<inf>2</inf> nanorods with partially isolated columnar structure can be constructed due to the enhanced shadowing and limited addtom diffusion effect. The average transmission of the vertically align SiO<inf>2</inf> nanorods were higher than the glass substrate reference sample over the visible wavelength range at all incident angle due to the transition in the refractive index profile from air to the nanostructure layer that improved the anti-reflection characteristics.
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    A comparative study on omnidirectional anti-reflection SiO2 nanostructure films coating by glancing angle deposition
    (2018-01-01)
    Prachachet, R.
    ;
    Samransuksamer, B.
    ;
    Horprathum, M.
    ;
    Eiamchai, P.
    ;
    Limwichean, S.
    Fabricated omnidirectional anti-reflection nanostructure films as a one of the promising alternative solar cell applications have attracted enormous scientific and industrial research benefits to their broadband, effective over a wide range of incident angles, lithography-free and high-throughput process. Recently, the nanostructure SiO<inf>2</inf> film was the most inclusive study on anti-reflection with omnidirectional and broadband characteristics. In this work, the three-dimensional silicon dioxide (SiO<inf>2</inf>) nanostructured thin film with different morphologies including vertical align, slant, spiral and thin films were fabricated by electron beam evaporation with glancing angle deposition (GLAD) on the glass slide and silicon wafer substrate. The morphological of the prepared samples were characterized by field-emission scanning electron microscope (FE-SEM) and high-resolution transmission electron microscope (HRTEM). The transmission, omnidirectional and birefringence property of the nanostructure SiO<inf>2</inf> films were investigated by UV-Vis-NIR spectrophotometer and variable angle spectroscopic ellipsometer (VASE). The spectrophotometer measurement was performed at normal incident angle and a full spectral range of 200 - 2000 nm. The angle dependent transmission measurements were investigated by rotating the specimen, with incidence angle defined relative to the surface normal of the prepared samples. This study demonstrates that the obtained SiO2 nanostructure film coated on glass slide substrate exhibits a higher transmission was 93% at normal incident angle. In addition, transmission measurement in visible wavelength and wide incident angles -80 to 80 were increased in comparison with the SiO2 thin film and glass slide substrate due to the transition in the refractive index profile from air to the nanostructure layer that improve the antireflection characteristics. The results clearly showed the enhanced omnidirectional and broadband characteristic of the three dimensional SiO2 nanostructure film coating.
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    Compact split circular ring shape dual-band antenna with open ring and additional strip
    (2016-09-06)
    Chawanonphithak, Yuktitath
    ;
    Phongcharoenpanich, Chuwong
    A dual-band antenna designed at the wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) bands is presented compact split circular ring shape dual-band antenna with open ring and addition strip. Its size is compact by the recondition circular ring shaped resonator connected. The antenna is fabricated onto a printed circuit board (PCB) on FR-4 substrate and the relative permittivity of 4.4, an overall size of 23 mm × 30 mm × 0.8 mm. This antenna can easily adjusted with open ring and strip to match impedance using a 50 ohm transmission line with SMA connector. The measured results show that the compacted antenna achieves a dual-band operating bandwidth from 2.38 GHz to 2.56 GHz and 4.66 GHz to 7.29 GHz for 11 S below -10 dB and the antenna yields omnidirectional patterns. The measured gains of the antenna from 2.45 and 5.5 GHz frequencies are 1.55 dBi and 3.2 dBi, respectively.
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    Compact dual-band I-shaped patch antenna with longitudinal strip on inverted-T ground plane
    (2014-01-01)
    Chawanonphithak, Yuktitath
    ;
    Phongcharoenpanich, Chuwong
    This paper presents a compact dual-band I-shaped patch antenna with longitudinal strip on inverted-T ground plane for wireless local area network (WLAN) applications over the frequency band of 2.400-2.484 GHz and 5.150-5.350 GHz. The I-shaped patch antenna and inverted-T ground plane are etched onto a piece of printed circuit board (PCB) with an overall size of 40 mm × 60 mm × 1.6 mm. It is excited by strip line to match impedance with a 50 ω transmission line. The measured results show that the miniaturized antenna achieves a broad operating bandwidth of 2.26-2.89 GHz and 4.92-5.83 GHz for S<inf>11</inf><-10 dB and omnidirectional radiation pattern. The measured gains of the antenna at 2.4 GHz and 5.2 GHz frequencies are 1.90 dBi and 3.45 dBi, respectively. © 2014 IEEE.
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    Miniaturized dual-band II-shaped monopole antennas with modified rectangular ground plane
    (2014-01-01)
    Chawanonphithak, Yuktitath
    ;
    Phongcharoenpanich, Chuwong
    Dual-band antenna covering IEEE 802.11a/b/g bands is presented using a miniaturized II-shaped monopole antennas with modified rectangular strip ground plane for dualband WLAN operation over the frequency band of 2.400-2.484 GHz, 5.150-5.350 GHz and 5.725-5.825GHz. The II-shaped monopole antenna and with modified rectangular ground plane are etched onto a piece of printed circuit board (PCB) with an overall size of 25 mm × 44 mm × 1.6 mm. This antenna can easily be fed by strip line to match impedance using a 50 ohm transmission line with SMA connector. The measured results show that the miniaturized antenna achieves a broad operating bandwidth of 2.26-2.89 GHz and 4.92-5.83 GHz for -S<inf>11</inf>-< -10 dB and omnidirectional radiation pattern. The measured gains of the antenna from 2.400 to 2.484 GHz and 5.150 to 5.825 GHz frequencies are 1.3 dBi and 2.5 dBi, respectively. © 2014 IEEE.