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 217

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Electromagnetic wave scattering on 2D PEC cylinders using complex source point techniques and uniform geometrical theory of diffraction
(2010-07-30)
Lertwiriyaprapa, T.
;
Phaebua, K.
;
Phongcharoenpanich, C.
;
Krairiksh, M.
An analysis of the path loss in the durian orchard is presented by using the complex source point technique (CSP) and the uniform geometrical theory of diffraction (UTD). The 2D Gaussian beams (GBs) expansion scattered by 2D cylindrical structures are presented. The GB can be generated by using the CSP. The GBs expansion can provides an efficient way of the synthesis of the radiation pattern of the antenna. The cylindrical structures are preliminarily assumed to be a perfect electric conductor (PEC). The source (square patch antenna) is located on a durian. The CST-program uses to simulate the source pattern including the effect of durian for the UTD calculation. The CSP-UTD is applied to analyze the scattered fields from the cylindrical structures. The multi-path propagation and the path loss prediction in various aspects are then obtained. Also, the exact solution of the CSP scattered by a cylindrical is used to compare the UTD results. The good agreements are obtained in this work.
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Design of a spherical array self-mixing oscillator antenna
(2001-12-01)
Krairiksh, Monai
;
Buasomboon, Wanlika
;
Ngamjanyaporn, Phaisan
;
Phongcharoenpanich, Chuwong
Principle of a spherical array self-mixing oscillator antenna is discussed in this paper. Applying the injection locking technique to the spherical array which elements are made of simple waveguide radiators, the beam steering with considerably constant pattern in different directions can be achieved without using the sophisticated phase shifters. This antenna is designed and tested at the frequency of 10 GHz.
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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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Synthesis of the antenna array pattern accomplishing the tapered minor lobe distributions
(2000-01-01)
Phongcharoenpanich, C.
;
Lertwiriyaprapa, T.
;
Krairiksh, M.
This paper presents the synthesis of the array antenna pattern accomplishing the tapered minor lobes for the applications of radar and low noise systems. Some orthogonal polynomials, viz. Legendre and the second kind Tschebyscheff polynomials are used to synthesize the array antenna pattern and compared with the conventional discretized one parameter Taylor method. These tapered minor lobe array patterns are also comparatively demonstrated together with the array pattern yielding the uniform minor robe, i.e. the first kind Tschebyscheff array. The array characteristics for various side lobe levels such as radiation pattern, half-power beamwidth, first-null beamwidth, directivity, the nearest to the furthest minor lobe ratio, and beam efficiency are illustrated. The advantages and disadvantages of each method are summarized.
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A unidirectional beam antenna using a probe excited rectangular ring near the reflector
(2002-01-01)
Phongcharoenpanich, C.
;
Lamultree, S.
;
Kosulvit, S.
;
Krairiksh, M.
This paper proposes a unidirectional beam antenna using a probe excited rectangular ring near the reflector. The antenna structure is simple. The radiation characteristics of the antenna for various spacings between the probe excited rectangular ring and the reflector are analyzed. These characteristics are also compared with the conventional single aperture near the reflector. It is found that the proposed structure yields better characteristics than the conventional structure. The numerical results of the radiation pattern, elevational beam peak, beamwidth, and maximum directivity are investigated. The result of the analysis is very useful for the design of antennas of high directivity with unidirectional beam.
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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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Resolution Improvement in Preharvest Sensor
(2019-10-01)
Dao, Hoang Nam
;
Krairiksh, Monai
This work illustrates the benefit of subtracted beam antenna we presented earlier for a sensor system in fruit pre-harvesting. The angular resolution pattern of a receiving antenna that shows how far the unwanted object (fruit) can be eliminated from the desired target (fruit under test) is proposed. The link budget for the beam subtracted antenna is also calculated to indicate the transmitting power for ensuring the receiving power for a normal sensitivity of the sensor. This calculation shows that the beam subtracted antenna can be employed in pre-harvesting of fruits.
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Dual beam Yagi patch antenna
(2015-10-22)
Samree, S.
;
Getjulom, S.
;
Teangrod, S.
;
Kittiyanpunya, C.
;
Krairiksh, M.
This paper presents a dual beam Yagi patch antenna. The antenna operates in the ISM band of 2.41 and 2.45 GHz. It consists of rectangular patch fed at two different probe positions. The patch has two reflectors each provides directional pattern in two perpendicular directions. The isolation is better than 20 dB and directivity is more than 3 dBi. This antenna can be applied for receiving video signals from wireless cameras.
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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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