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An annular microstrip antenna with sectoral slots for RFID reader
(2009-12-01)
Suwalak, Rattapong
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Pongpaibool, Pornanong
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Phongcharoenpanich, Chuwong
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Krairiksh, Monai
This paper presents an annular microstrip antenna with two sectoral slots fed by a coaxial probe on a square vertical ground plane. The proposed microstrip antenna can support the dual-band operation (UHF and microwave RFID bands). From the results, the antenna has the magnitude of S11 less than -10 dB along the bandwidth of 32 MHz (3.51%) for UHF band and 140 MHz (5.76%) for microwave band. The unidirectional beam can be achieved by the proposed microstrip antenna. The beamwidth in xz- and yz-planes is 82.8 and 89 degrees at the center frequency of 922.5 MHz and beamwidth in xz- and yz-planes is 39.8 and 28 degrees at the center frequency of 2.45 GHz, respectively. This antenna has efficiently high directivity for both bands. The simulation and measurement results are shown. ©2009 IEEE.
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A hybrid ring coupler quasi-optical antenna-mixer
(2009-01-17)
Janin, Suwan
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Sripimanwat, Keattisak
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Phongcharoenpanich, Chuwong
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Krairiksh, Monai
This paper proposes a hybrid ring coupler quasi-optical antenna-mixer for mitigating local oscillator retransmission. By demonstrating at K-band, the antenna element consists of back-to-back aperture coupled inverted square patch antenna to couple the RF signal at 18.8 GHz to the sigma port of a hybrid ring mixer while the LO signal at 17.5 GHz is coupled to the delta port. The HSCH-9101 Schottky diodes are used to transform the RF signal to the intermediate frequency signal at 1.3 GHz. The results show that the RF/LO isolation is better than 29 dB at 18.19 GHz, and the isotropic conversion loss of the down converted signal is better than 16 dB at 19.25 GHz. The application of the interest is an inverse measurement technique for dielectric property determination. © 2007 Elsevier GmbH. All rights reserved.
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Wordlength effect on CMA adaptive antenna with digital beam synthesis initialization
(2008-12-01)
Boonpoonga, Akkarat
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Tantisopharak, Tanawut
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Sirisuk, Phaophak
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Krairiksh, Monai
This paper investigates the wordlength effect on the CMA adaptive antenna with digital beam synthesis initialization. The antenna is a four-element circular array whose main beam can be switched into different directions by using digital beam synthesizer. A beam obtained from digital beam synthesis is exploited as an initial beam for CMA. A weight vector for generating initial beams of CMA is chosen by determining radiation patterns. The SINR of the digital beam synthesis-based CMA adaptive antenna with different wordlengths are shown. Moreover, the step-size constant of CMA is also investigated and properly chosen to avoid underflow and overflow phenomena. © 2008 IEEE.
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Statistical characteristic measurements of propagation in durian orchard for sensor network at 5.8 GHz
(2008-12-01)
Phaebua, Kittisak
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Suwalak, Rattapong
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Phongcharoenpanich, Chuwong
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Krairiksh, Monai
The statistical characteristic measurement results of wireless sensor network in durian orchard at 5.8 GHz are presented. The measurement results are performed to study the channel characteristic of the radio wave propagation in the durian orchard. The communication channel is connected from sensor node to communication node and between communication node. The transmitter is setup at the bole of a durian tree for one communication node, and the received power by spectrum analyzer is used for the other communication node. Moreover, the transmitter is setup on the branch of durian tree for the sensor node placed on a durian. The signal strength is measured by spectrum analyzer. The sampling time of two seconds is employed to collect the signal strength for histogram plot. The statistical models, such as the Rican distribution and normal distribution are employed to fit the measurement results. These results can be used to approximate the statistical channel characteristics to predict the bit error rate in the wireless sensor network systems in durian orchard at 5.8 GHz. © 2008 IEEE.
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Path loss model and measurements of 5.8 ghz wireless network in durian garden
(2008-12-01)
Suwalak, Rattapong
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Phaebua, Kittisak
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Phongcharoenpanich, Chuwong
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Krairiksh, Monai
This paper presents the path loss model and measurement of wireless network in durian garden at 5.8 GHz. This study is important in wireless communication system for predication and design the communication system of durian garden such as communication range, power transfer, position of transmitting and receiving antenna. From the results, it is obvious that the path loss at the distance of 128 m from the transmitter is less than -50 dB. © 2008 IEEE.
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Electric field and temperature distributions of a continuous fluidized bed microwave paddy drying system
(2008-12-01)
Sangdao, Chokchai
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Krairiksh, Monai
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Parallel multistage CM array with constrained initialization of digital beam synthesis
(2008-12-01)
Boonpoonga, Akkarat
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Tantisopharak, Tanawut
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Sirisuk, Phaophak
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Krairiksh, Monai
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Magnetic field distributions of two-slot array antenna on a concentric sectoral cylindrical resonator excited by a coupling slot
(2008-12-01)
Wounchoum, Phairote
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Worasawate, Denchai
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Phongcharoenpanich, Chuwong
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Krairiksh, Monai
in this paper, the magnetic field distribution of two-slot array antenna on a concentric sectoral cylindrical resonator excited by a coupling slot is presented. The correlations between the field distributions of the antenna and the mode-based field distributions are presented. The radiation pattern, magnetic field distribution and magnitude of S11 are investigated in the terms of the length of the sectoral resonator. It shows that the TE112 mode has degenerated to the magnitude of S11 for the circumferential slot array antenna. The results provide useful information for the design of switched-beam array antenna on the concentric sectoral cylindrical resonators. ©2008 IEEE.
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A portable dielectric-property determination system using coupled antennas
(2008-11-06)
Mearnchu, Jhirat
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Limpiti, Thunyawat
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Torrungrueng, Danai
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Akkaraekthalin, Prayoot
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Krairiksh, Monai
This paper presents a dielectric-property determination system that measures magnitude of reflection and coupling coefficients of coupled antennas. They are plotted on a ε<inf>r</inf>′ ε<inf>r</inf>″ plane, and the intersection of these two quantities provides the value of ε<inf>r</inf>′ and ε<inf>r</inf>″. Measurement results of paddy validate the effectiveness of the proposed technique. The system provides accurate results. The error from the results of proposed system differs from the use of network analyzer of less than 4 %.
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Dielectric-property determination from measurement of magnitude of reflection and coupling coefficients of coupled antennas
(2008-10-06)
Mearnchu, Jhirat
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Limpiti, Thunyawat
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Torrungrueng, Danai
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Akkaraekthalin, Prayoot
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Krairiksh, Monai
This paper presents a dielectric-property determination technique that measures the magnitudes of the reflection and coupling coefficients of coupled antennas. They are plotted on the ε′<inf>r</inf> ε″ <inf>r</inf> plane, and the intersection of these two quantities provides the values of ε′<inf>r</inf> and ε″<inf>r</inf> where ε′<inf>r</inf> is the real part and ε″<inf>r</inf> is the imaginary part of the relative complex permittivity. Measurement results of water validate the effectiveness of the proposed technique. This technique provides a compact measurement system and is suitable for localized dielectric determination. ©2008 IEEE.

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