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ABSTRACT: In this study, the temperature distribution of a material (frozen tuna) that was heated in a commercial microwave oven is calculated by a coupled method using the finite-difference time-domain method, the semi-implicit method for pressure linked equations, the Monte Carlo method, and the radiative energy absorption distribution method. This method takes into consideration the melting heat during the phase change and the change in real and imaginary parts of the complex relative permittivity and heat conductivity during defrosting. Meanwhile, the temperature distribution of a sample of the frozen tuna is measured using an identical microwave oven and a thermograph. Then, the computed and monitored temperature distributions are compared. The calculated temperature distribution is found to agree well with the measured one, and the validity of the coupled method is confirmed. Additionally, the temperature distribution of a frozen heated material is verified both experimentally and theoretically.
IEEE Transactions on Microwave Theory and Techniques 06/2010; · 1.85 Impact Factor
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ABSTRACT: In this research, temperature distribution of a pyramidal EM-absorber under high power injection is computed by a coupled method called FDTD-SIMPLE-MR method. In this method, both electromagnetic field and all the heat transmission phenomena such as heat transportation, heat transfer by air convention and heat radiation can be calculated. Moreover, temperature distribution of a pyramidal EM-absorber is examined experimentally by using high power RF instruments. Then both the computed and the experimetal results are compared and examined. Average temperature difference between these temperature distribution results in about 4 degrees.
Microwave Conference, 2007. APMC 2007. Asia-Pacific; 01/2008
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ABSTRACT: Utilization of electromagnetic absorbers under high power is increasing. The absorbers are used in anechoic chambers for estimation of performance of high power radars. Variation of the absorption characteristics of the absorbers under such condition is expected, due to the generation of heat or temperature change. In this paper, first temperature distribution of a pyramidal EM-wave absorber under high power injection is examined using the coupled method. The coupled method can calculate electromagnetic field and all of the heat transmissions (heat transport, heat transfer and heat radiation). Next, the power injection experiment is examined using the absorber and high power instruments to get the temperature distribution experimentally. Finally the calculated and measured temperature distributions of the absorber are compared, discussed and evaluated.
Microwave Conference, 2007. European; 11/2007
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ABSTRACT: In this paper, first the temperature distribution of λ/4 type EM-absorber under high power injection is calculated using the coupled method. The coupled method can calculate electromagnetic field, and all the heat transmission phenomena of heat transport, heat transfer by air convection, and heat radiation. Next, the calculated and measured temperature distributions on the surface of the absorber are compared. As a result, the calculated distribution agrees well with the measured one. The internal temperature of the absorber is also obtained from the coupled method.
Electromagnetic Compatibility and Electromagnetic Ecology, 2007 7th International Symposium on; 07/2007
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ABSTRACT: In this paper, uneven temperature distribution of a heated material is computed by the coupled method. The coupled method can calculate electromagnetics, and all of the heat transmission phenomena of heat conduction, heat transfer by air convection, and heat radiation. The calculated temperature distribution at the surface of the material is compared with the measured one. As a result, the tendency of the calculated and measured temperature distributions agrees well. The validity of the proposed method on this kind of problem is verified. The temperature of the surrounding air is also confirmed by the computation including the temperature in the phantom.
Electromagnetic Compatibility and Electromagnetic Ecology, 2007 7th International Symposium on; 07/2007
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ABSTRACT: In this paper, first, FDTD, semi-implicit method for pressure linked equations (SIMPLE), Monte Carlo and radiative energy absorption distribution (READ) methods are combined to calculate electromagnetic field and all the heat transfer phenomena of heat transport, heat transfer by air convection and heat radiation (It is called FDTD-SIMPLE-MR method.). The temperature distribution of an one-layer EM-absorber using a lossy dielectric material under high power injection is calculated using FDTD-SIMPLE-MR method and a traditional method. And the both calculated temperature distributions of the absorber are compared. As a result, the more detailed temperature distribution of the absorber is obtained by FDTD-SIMPLE-MR method.
Microwave Conference, 2006. APMC 2006. Asia-Pacific; 01/2007
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ABSTRACT: In this paper, first, FDTD, semi-implicit method for pressure linked equations (SIMPLE), Monte Carlo and radiative energy absorption distribution (READ) methods are combined to calculate electromagnetic field and all the heat transfer phenomena of heat transport, heat transfer by air convection and heat radiation (It is called FDTD-SIMPLE-MR method.). The temperature distribution of A/4 type EM-absorber using resistive film under high power injection is calculated using FDTD-SIMPLE-MR method. Next, the high power injection experiment is conducted using an absorber and high power RF instruments to get the temperature distribution experimentally. Finally, the calculated and measured temperature distributions of the absorber are compared. As a result, the calculated temperature distribution by FDTD-SIMPLE-MR method agrees well with the measured one and the validity of FDTD-SIMPLE-MR method is confirmed
Microwave Conference, 2006. 36th European; 10/2006
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ABSTRACT: In this paper, temperature distribution of heated material (a frozen tuna) in a microwave oven is calculated by the method which combines FDTD for electromagnetic field calculation with heat transport equation considering melting heat and the nonlinear and rapid change of complex relative permittivity and heat conductivity during defrosting. As a result, the calculated temperature distribution of heated material agrees well with the measured one, and the validity of the combined method considering melting heat and the change of complex relative permittivity and heat conductivity is confirmed
Microwave Symposium Digest, 2006. IEEE MTT-S International; 07/2006
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ABSTRACT: Radiowave absorbers are frequently used in high power applications, such as radar sites, and the rise of temperature of the absorber has often become a matter of concern. In this paper, the finite-difference time-domain (FDTD) method combined with the heat transport equation (HTE), also known as the FDTD-HTE method, which has been widely used in the analysis of microwave heating or temperature increase in the human head due to portable phones, is used in the analysis of the wave absorption characteristics of a single-layer wave absorber. The complex permittivity of a sample made of epoxy resin, measured by a cavity-resonator method when the sample is irradiated by a high power field for different irradiation times, is used in the analysis, and the wave absorption characteristics of the absorber under investigation highly depend on the input power and irradiation time of the high power field.
IEEE Transactions on Electromagnetic Compatibility 12/2005; · 1.18 Impact Factor
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ABSTRACT: In this paper, we propose a method for analyzing one dimensional electromagnetic field employing constrained interpolation profile (CIP) method, characteristics curve method and time splitting method incorporated into the EM field equation considering lossy dielectric and magnetic materials in the domain of analysis. And also, the proposed method is applied to multi-dimensional EM field analysis. As a result, the validity of the CIP method applying EM field to compare FDTD method is confirmed.
Microwave Conference, 2005 European; 11/2005
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ABSTRACT: Electromagnetic (EM) wave absorbers have been used for improving the EM environment of an electronic toll collection system on an express highway or a wireless local area network system in an indoor environment. In this paper, an efficient multiray propagation model, which uses three-dimensional geometry and image techniques to trace multiple signal rays from transmitter to receiver, is employed to analyze the EM environment of a dedicated short-range communication (DSRC) system on an express highway. The validity of the model employed is discussed by a comparison with the results obtained by an experiment on the highways when a right-circular polarized transmitter and receiver are used. The analysis shows that the possible undesired communications between onboard equipment that acts as a receiver and DSRC beacon, which transmits the radio signals, is improved by increasing the EM wave-absorption capability of the sidewalls and the pavement of the highway. Another advantage of the employed model is that it is effective for investigating the location of wave absorbers to be set up on the highway, and it takes only a fraction of a minute for computation.
IEEE Transactions on Microwave Theory and Techniques 10/2005; · 1.85 Impact Factor
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ABSTRACT: This paper describes the temperature distribution analysis of lambda/4 type EM-absorber using resistive film when high electric power is injected to the absorber. For the temperature analysis, FDTD method is used to analyze electromagnetics and SIMPLE (semi-implicit method for pressure linked equations) method is used for calculation of heat transport and air convection enabling to analyze local heat transfer more strictly than heat transport equation (HTE) method which is the traditional heat transport analysis method. And we propose four types of wave absorbers to analyze these temperature distribution on the resistive film to find the best type with least temperature rise. As a result, when glass and metal plates are used for spacer and reflector, respectively, the absorber proved to be the best one from a view point of temperature descent. And it is shown that the temperature range does not cause the change of absorbing characteristics in the analysis but the temperature rise exceeds 160 degC, the characteristics may change
Electromagnetic Compatibility, 2005. EMC 2005. 2005 International Symposium on; 09/2005
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ABSTRACT: Electromagnetic (EM) wave absorbers have been used to improve the EM environment of an electronic toll collection (ETC) system on an express highway or a wireless local area network (LAN) system in an indoor environment. In this paper, an efficient multi-ray propagation model, which uses a combination of image technique and grid approach to trace multiple signal rays from transmitter to receiver, is employed to analyze the EM environment of a dedicated short-range communication (DSRC) system inside tunnel. The validity of the model employed is discussed by the comparison with the results obtained by an experiment inside tunnel.
Electromagnetic Compatibility, 2005. EMC 2005. 2005 International Symposium on; 09/2005
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ABSTRACT: Design methodologies of planar duplexer and triplexer consisting of bandpass filters (BPFs) using different tapped resonators are described. Firstly, we propose a planar duplexer consisting of BPFs using a tapped half-wavelength resonator and a tapped quarter-wavelength resonator. The duplexer is designed based on a classical filter design method with a narrow-band approximation and a tap-coupling method. The experimental duplexer is fabricated using coplanar-waveguide structures. Secondly, a planar triplexer consisting of three types of BPFs is described in a similar manner. The results of this study show that the design methodology is useful for realizing the high-performance planar duplexer and triplexer fabricated without increasing the number of elements.
IEEE Transactions on Microwave Theory and Techniques 07/2005; · 1.85 Impact Factor
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ABSTRACT: An efficient multi-ray propagation model, which uses 3D geometry and image techniques to trace multiple signal rays from transmitter to receiver, is employed to analyse the electromagnetic environment of a dedicated short-range communication system on an express highway. The employed model is effective for investigating the location of EM wave absorbers to be set up on the highway, and it takes only a fraction of a minute for computation.
Electronics Letters 10/2004; · 0.96 Impact Factor
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ABSTRACT: Resonant characteristics of a microstrip resonator loaded with dielectric rods below a strip conductor are investigated by a finite-difference time-domain method. A tapped resonator employing the proposed method is capable of realising the improved spurious responses together with an attenuation pole in the stopband, and of reducing the resonator's length.
Electronics Letters 05/2004; · 0.96 Impact Factor
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ABSTRACT: This paper describes propagation modes of leakage waves irradiated from a microwave oven examined by using finite difference time domain(FDTD) method. In this study, the amplitude coefficient in each mode of leakage waves is calculated under the use of the amplitude level of the electric field about these unwanted waves, and the percentage of each mode is also calculated. Furthermore, shielding effectiveness(SE) of choke structure for suppressing the leakage waves is calculated using combined waves composed of the higher order modes as each percentages. As a result, the percentage of each mode included in the leakage waves is examined quantitatively. The approximation analysis of the SE of the choke structure can also be carried out. Therefore, efficient method for analyzing the door structure of the oven has been established without the use of the memory for the calculation.
Microwave Conference, 2003. 33rd European; 11/2003
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ABSTRACT: This paper presents a planar duplexer consisting of mixed bandpass filters (BPFs) using different tapped resonators. The duplexer is designed based on the general filter design and tap-coupling technique. The actual duplexer is fabricated by coplanar waveguide (CPW) structure. The results of this study lead us to the conclusion that the proposal is useful for realizing the high performance planar duplexer fabricated without increasing the number of elements.
Radio and Wireless Conference, 2003. RAWCON '03. Proceedings; 09/2003
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ABSTRACT: Improvement of the skirt characteristics of a λ/4 resonator bandpass filter (BPF) is carried out by placement of attenuation poles. In this study, the characteristics of the tapped-resonator are effectively used because the attenuation pole can easily be realized, and the external Q of the resonator can be controlled. However, the technique includes the limitation of flexibility for the placement control of the attenuation pole. Therefore, we try to improve flexibility for placement control of the attenuation pole under the characteristics of the lumped-element loaded stub. It has been clarified that the proposed technique is useful for improving the skirt characteristics of the λ/4 resonator BPF.
Circuits and Systems, 2002. APCCAS '02. 2002 Asia-Pacific Conference on; 02/2002
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IEEE Asia Pacific Conference on Circuits and Systems 2002, APCCAS 2002, Singapore, 16-18 December 2002; 01/2002
