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ABSTRACT: This paper proposes a design method of arbitrarily- shaped bandpass filters with multiple resonators in the limited space. Although the proposed method is based on the genetic- algorithm (GA) optimization, we newly introduce the fitness function which estimates not only the magnitude of S-parameters but also the phase characteristics in a passband. Conventional GAs without phase evaluation are difficult to design a filter having the specified number of resonators efficiently, whereas the present method can easily construct such a filter. As an example, arbitrarily-shaped planar-circuit filters with 3 and 4 resonators are optimized in the limited space and fabricated. The effectiveness of the present technique is verified by comparison of frequency responses between the calculated and the measured results.
Microwave Conference, 2007. European; 11/2007
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ABSTRACT: This paper proposes a design method of arbitrarily-shaped bandpass filters with multiple resonators in the limited space. Although the proposed method is based on the genetic-algorithm (GA) optimization, we newly introduce the fitness function which estimates not only the magnitude of S-parameters but also the phase characteristics in a passband. Conventional GAs without phase evaluation are difficult to design a filter having the specified number of resonators efficiently, whereas the present method can easily construct such a filter. As an example, arbitrarily-shaped planar-circuit filter with 3 and 4 resonators are optimized in the limited space and fabricated. The effectiveness of the present technique is verified by comparison of frequency responses between the calculated and the measured results.
Microwave integrated circuit conference, 2007. eumic 2007. european; 11/2007
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ABSTRACT: This paper presents a high-performance waveguide filter constructed by novel metallic resonant windows, which have a resonant characteristic with two attenuation poles on both sides of a passband, that is, a dual-behavior resonance. Such resonant windows make it possible to produce multiple attenuation poles without any additional coupling structures, thereby realizing a compact and light-weight filter. As a design example, a 3-pole Chebyshev waveguide filter with six attenuation poles at X band was shown. The validity of the filter is proven by the comparison of the frequency characteristics between the calculated and the measured results
Microwave Conference, 2006. 36th European; 10/2006
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ABSTRACT: This paper develops novel waveguide filters consisting of frequency-selective surfaces (FSSs) in order to realize both the drastic size reduction and multiple attenuation poles in stopbands at both sides of passband. The FSS provides not only a passband but also attenuation-pole frequencies in stopbands since the FSS has both the aperture-element and the patch-element behaviors. In the present design method, the shape of each FSS is designed by a genetic algorithm so that the resonant curve of FSS can be fitted to that obtained from an equivalent-circuit approach. By using such FSSs and quarter-wavelength waveguides, a bandpass filter with six attenuation poles like an elliptic-function filter has been constructed. Furthermore, a technique of the size reduction by controlling adequately the resonant response of each FSS is presented. In this filter, the FSSs are closely located at the interval of the length much shorter than a quarter wavelength. It is shown from the design example that the half longitudinal length of the former example can be obtained, keeping both the passband response and attenuation poles in stopbands. The effectiveness of the waveguide filters with FSSs is validated by good agreement between the calculated and the measured results.
IEEE Transactions on Microwave Theory and Techniques 12/2005; · 1.85 Impact Factor
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ABSTRACT: This paper proposes a new element shape of frequency selective surface (FSS) for designing a waveguide filter with multiple attenuation poles like an elliptic-function filter. The FSS is a dual-behavior resonator by the combination of the aperture-type and the patch-type FSSs. Introducing such FSSs can realize high skirt selectivity by utilizing anti-resonances (full reflection) in stopbands at both sides of passband in addition to resonance (full transmission) in a passband. To design the waveguide filter, the resonant characteristics for various geometrical parameters of the FSS are investigated. As a design example, we demonstrate the bandpass filter with 4% bandwidth at the center frequency 10 GHz. The effectiveness of the waveguide filter with the FSSs proposed here is validated by good agreement between the calculated and the measured results.
Microwave Conference, 2005 European; 11/2005
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ABSTRACT: This paper proposes a waveguide filter consisting of frequency selective surfaces (FSS) with an arbitrarily-shaped element, which can control not only a passband characteristic but also attenuation-pole frequencies at stopbands. In the present design method, the shape of each FSS is designed by a genetic algorithm (GA) so that the resonant curve of the FSS can be fitted to that obtained from an equivalent-circuit approach. By using such FSSs, we have constructed the bandpass filters with 4% bandwidth at the center frequency 10 GHz, in addition to multiple attenuation poles like an elliptic-function filter. The effectiveness of the waveguide filter with FSSs proposed here is validated by good agreement between the calculated and the measured results.
Microwave Symposium Digest, 2005 IEEE MTT-S International; 07/2005
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ABSTRACT: This paper proposes an optimization-design method for the frequency selective surface (FSS) based on the genetic algorithm (GA) incorporated with a geometry-refinement technique. The present method takes the connectivity condition of the elements into consideration, thereby resulting in an easy fabrication. As an example, we design the multiband single-layer FSS for transmitting L band (1.5 GHz band) and S band (2.5 GHz band) and also reflecting Ka band (20/30 GHz band). The designed FSS has bandwidths broader than previous FSSs. Finally, the validity of the present method is proved by the agreement between the calculated and the measured transmission responses for the designed FSS.
IEEE Transactions on Antennas and Propagation 12/2004; · 2.15 Impact Factor
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ABSTRACT: We have developed multiband single-layer frequency selective surfaces (FSS) by using the optimization technique based on the genetic algorithm (GA). In the frequency responses of these FSS for oblique incidence, unwanted sharp dips appear, depending on the element shape. Similar singular characteristics have been confirmed for a dipole element with the length of a wavelength. But the mechanism causing such singular characteristics has not been investigated for the FSS with the complicated element shape produced by the optimization technique. This paper makes it clear how the singular characteristics of the FSS occur in the frequency response. Firstly, we show briefly the methods for finding the singular frequency with unwanted sharp dips, and also the resonant frequency yielding the specified reflection. Then, by using an example of the FSS developed by us, we explain the mechanism of the singular characteristics from the current distribution. Finally, the validity of the discussion is proved experimentally.
Wireless Communication Technology, 2003. IEEE Topical Conference on; 11/2003
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ABSTRACT: This paper has developed a multiband single-layer frequency selective surface (FSS) designed by using the optimization technique (micro-genetic algorithm). The characteristics of the designed FSS are superior to those of the Fractal FSS in the close dual-band separation and to those of the convoluted double square loop FSS in the bandwidth. We design the FSS for transmitting L and S bands and reflecting Ku and Ka bands. The agreement between the calculated and measured transmission responses for the designed FSS proves the validity of the present method.
Microwave Conference, 2002. 32nd European; 10/2002
