Krairiksh, Monai

Preferred name

Krairiksh, Monai

Alternative Name

Krairiksh', Monai

Krairiksh, M.

Main Affiliation

School of Engineering

monai.kr@kmitl.ac.th

Now showing 1 - 10 of 81

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EBG-backed ultrawideband circularly polarized Archimedean spiral antenna scheme for IoT applications
(2025-12-01)
Luadang, Bancha
;
Ainthachot, Chalanthon
;
Janpangngern, Pisit
;
Pookkapund, Khanet
;
Torrungrueng, Danai
This research proposes a low-profile ultrawideband circularly polarized Archimedean spiral antenna with an electromagnetic band gap (EBG)-backed structure. The proposed antenna scheme consists of an upper-layer spiral radiator, a microstrip tapered balun, and a lower-layer high-impedance circular EBG reflector of three concentric rings of trapezoid-shaped unit cells. The antenna scheme can achieve a significant profile reduction, with a total height of 0.1 wavelengths at the lowest operational frequency. The integration of the EBG reflector improves the radiation characteristics and antenna gain, achieving a maximum gain of 9.87 dBic at 6.90 GHz. The EBG reflector also improves impedance matching and axial ratio (AR) over the 1.5–8.75 GHz frequency range, achieving a wide AR bandwidth of 141.46%. The novelty of this work lies in the integration of Archimedean spiral antenna with high-impedance EBG reflector of trapezoid-shaped unit cells to enhance the impedance and AR bandwidths without increasing the overall antenna profile. Essentially, the proposed antenna scheme is suitable for broadband communication systems that require ultrawide bandwidth, circular polarization, and a small form factor.
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Simple and Effective Design Concept for Constructing In-Situ Soil Dielectric Property Sensor with Dual Low-Cost COTS Microwave Modules
(2022-01-01)
Leekul, Prapan
;
Mgawe, Bonny
;
Kazema, Twahir
;
Dao, Hoang Nam
;
Sirisuk, Phaophak
This paper presents a compact sensor system for estimating the dielectric properties of materials based on commercial, off-the-shelf (COTS) modules. The dielectric constant and conductivity of a material under test can be determined from the measurement of the microwave reflected from the material. By using dual microwave sensor modules with a slightly different radio frequency, an identical intermediate frequency at the mixers of the modules was obtained. The intermediate frequency was chosen such that the associated microwave and data processing components could be easily obtainable, leading to a practical realization of the sensor system. Synchronization of the two microwave sensor modules was achieved using electronically controlled relays that simultaneously switch on the power supplies of both modules. Two microcontrollers were used to capture the corresponding signals. The sensor was designed at a 10 GHz band for measuring reflected waves from various kinds of materials, especially soils with different moisture and fertilizer contents. The evaluation results indicate a good agreement between the measured results from the proposed sensor and the ones from a network analyzer, verifying that the proposed sensor is fully functional for monitoring variation in the dielectric properties of materials, including soil. The average sensitivity for the dielectric constant of moist soil is 0.26/% moisture content and the error rate for dielectric constant measurement is 4.83%.
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Broadband Multi-Shaped Metasurface Circularly Polarized Antenna With Suppressed Non-CP Radiation Modes
(2023-01-01)
Supreeyatitikul, Nathapat
;
Lertwiriyaprapa, Titipong
;
Chudpooti, Nonchanutt
;
Krairiksh, Monai
;
Phongcharoenpanich, Chuwong
In this research, a multi-shaped metasurface broadband circularly polarized (CP) patch antenna with parasitic elements is proposed for 5G new radio (NR) applications. The proposed metasurface CP patch antenna comprises triple-layered substrates without air gap. The upper layer sits with multi-shaped metasurface elements and parasitic patches. The middle layer consists of an L-shaped slot functioning as the ground plane, and the lower layer contains a microstrip and a fan-shaped stub functioning as the feed line. The proposed metasurface CP patch antenna with parasitic elements is evaluated using characteristic mode analysis (CMA). The CMA results indicate that the modal significance of Modes 1 and 2 of the multi-shaped metasurface CP antenna are orthogonal, giving rise to circular polarization. The non-CP radiation of Modes 3 and 4 are suppressed by using the multi-shaped metasurface elements and parasitic patches. The measured impedance bandwidth and axial ratio bandwidth are 42.85% (3.4 - 4.9 GHz) and 38% (3.27 - 4.6 GHz), achieving the maximum gain of 7.23 dBic at 3.7 GHz. The experiments demonstrate that the multi-shaped metasurface CP patch antenna with parasitic elements is suitable for 5G NR wireless applications. The novelty of this study is attributed to its utilization of multi-shaped metasurface elements and parasitic patches, which effectively suppress non-circularly polarized radiation modes.
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A multibeam antenna using quasi-optical antenna-mixers
(2008-06-02)
Janin, Suwan
;
Sripimanwat, Keattisak
;
Phongcharoenpanich, Chuwong
;
Krairiksh, Monai
A multibeam antenna could be designed without using a complicated feeding system by using quasi-optical antenna-mixers. Accurate beam directions could be obtained when practical antenna patterns was taken into account in the design. The effectiveness of a three-beam antenna is demonstrated at K-band showing accurate beam directions which is very useful in modern wireless communications. © 2007 Elsevier GmbH. All rights reserved.
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Beam-Scanning Reflectometer for Detecting Granulated Fruits
(2017-03-01)
Kittiyanpunya, Chainarong
;
Leekul, Prapan
;
Phongcharoenpanich, Chuwong
;
Krairiksh, Monai
The problem of granulation in fruits costs vendors a big chunk of their revenue, hence a non-destructive sensor that can identify granulated fruits without destroying good fruits is highly desirable. This paper presents such a sensor system based on beam-scanning reflectometer operating at 2.45 GHz. Beams of scattered waves from several directions around the fruit are reflected by a conical reflector and scanned by a phased array of pattern reconfigurable Yagi-Uda antennas equipped with 1-b phase shifters for lowest loss in feed network. The collected data are used to calculate the Rician k-factor. The system was tested with plasticine spheres and real tangerines. It was found that the system with an eight-beam array was better than one with a four-beam array. This system may prove useful for quality control of tangerines and other agricultural products.
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A rhombic patch monopole antenna with modified minkowski fractal geometry for umts, wlan, and mobile wimax application
(2009-01-01)
Mahatthanajatuphat, C.
;
Saleekaw, S.
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Akkaraekthalin, P.
;
Krairiksh, M.
This paper presents a rhombic patch monopole antenna applied with a technique of fractal geometry. The antenna has multiband operation in which the generator model, which is an initial model to create a fractal rhombic patch monopole, is inserted at each center side of a rhombic patch monopole antenna. Especially, a modified ground plane has been employed to improve input impedance bandwidth and high frequency radiation performance. The proposed antenna is designed and implemented to effectively support personal communication system (PCS 1.85-1.99 GHz), universal mobile telecommunication system (UMTS 1.92-2.17GHz), wireless local area network (WLAN), which usually operate in the 2.4GHz (2.4-2.484GHz) and 5.2/5.8GHz (5.15-5.35 GHz/5.725-5.825 GHz) bands, mobile worldwide interoperability for microwave access (Mobile WiMAX), and WiMAX, which operate in the 2.3/2.5 GHz (2.305-2.360 GHz/2.5-2.69 GHz) and 5.5 GHz (5.25-5.85 GHz) bands. The radiation patterns of the proposed antennas are similar to an omnidirectional radiation pattern. The properties of the antenna such as return losses, radiation patterns and gain are determined via numerical simulation and measurement.
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Signal-to-interference ratio improvement by using a phased array antenna of switched-beam elements
(2005-05-01)
Ngamjanyaporn, Phaisan
;
Phongcharoenpanich, Chuwong
;
Akkaraekthalin, Prayoot
;
Krairiksh, Monai
A phased array antenna of switched-beam elements is proposed to improve the signal-to-interference ratio (SIR). By using 1-bit phase shifters, the main beam of the array is switched to desired signal direction, and with the switched-beam patch antenna elements the null patterns are changeable. The results of radiation patterns show that the interference suppression can be improved. Moreover, the SIR measurement is also set up in multipath environment to ensure the array performance. It is found that the SIR is significantly affected by the multipath environment; however, the SIR improvement of more than 10 dB can be obtained by changing the null patterns. © 2005 IEEE.
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Enhancement of enzymatic hydrolysis of lignocellulosic wastes by microwave pretreatment under atmospheric pressure
(2003-05-01)
Kitchaiya, P.
;
Intanakul, P.
;
Krairiksh, M.
A technique to improve enzymatic hydrolysis of lignocellulosic wastes by microwave pretreatment under atmospheric pressure was developed. Ground rice straw or sugar cane bagasse immersed in a glycerine medium with small amounts of water, was treated with 240 W of microwave irradiation for 10 min at atmospheric pressure. A temperature of about 200°C could be reached in this medium without high pressure build up. More than twice the amount of reducing sugars was produced from enzyme saccharification utilizing the microwave pretreatment, compared with no pretreatment. The microwave pretreatment which achieves high temperatures at atmospheric pressure provides some advantages over a steam explosion process which requires high pressure and a subsequent sudden pressure drop.
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Analysis and design of a Gaussian backscatter antenna with ring focus feed
(2010-12-01)
Thaiwirot, W.
;
Wongsan, Rangsan
;
Krairiksh, M.
This paper presents analysis and design of a Gaussian backscatter antenna with ring focus feed. The curvature of main reflector is Gaussian, and the subreflector is a portion of an ellipse. The antenna has axial symmetry. A backscattering technique is used with the main reflector to achieve wide beamwidth. The input parameters of the proposed antenna are derived in closed form. Physical theory of diffraction (PTD) is used to analyze the radiation pattern of the proposed antenna and verified with experimental results. The effects of the support structures on the radiation patterns of the proposed antenna have been investigated experimentally. The proposed antenna can produces high gain and wide beamwidth (coverage angle θ = ±65°). This antenna can be used for realizing earth coverage beam in LEO satellite or indoor wireless LAN applications.
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An extended ZY T-chart for conjugately characteristic-impedance transmission lines with active characteristic impedances
(2007-08-01)
Torrungrueng, D.
;
Chou, P. Y.
;
Krairiksh, M.
It has been shown recently in the literature that the conjugately characteristic-impedance transmission lines (CCITLs) implemented by periodically loaded lossless lines can exhibit active characteristic impedances (i.e., negative characteristic resistances). In this case, the magnitude of the voltage reflection coefficient is always greater than or equal to unity for passive load termination. Because of this reason, some modifications to the standard T-chart, a graphical tool for solving CCTTL problems, is necessary. The modified chart is called as an extended ZY T-chart, where the range of plotting is always outside or on the unit circle of the voltage reflection coefficient Γ plane. It is found that the extended chart depends on the angle Φ, the argument of the CCITL characteristic impedances, in a complicated fashion. © 2007 Wiley Periodicals, Inc.

Krairiksh, Monai

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