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A novel quad-band bandpass filter with individually controllable centre frequencies and bandwidths using a folded stepped-impedance resonator (SIR) is proposed. The new filter that centres at 2.4, 3.3, 4.1 and 5.2 GHz has a measured passband insertion loss of no more than 1.6 dB, and has a miniature circuit size of 0.448λ g × 0.027λ g. The presented filter is fabricated and tested, and the experiment demonstrates the new design. The new quad-band bandpass filter has compact and simple circuit topology, good performance of low passband insertion loss and transmission zeros, and greatly reduced circuit size compared with the relative reports.

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[1] Water quality evaluation entails both randomness and fuzziness. Two hybrid models are developed, based on the principle of maximum entropy (POME) and engineering fuzzy set theory (EFST). Generalized weighted distances are defined for considering both randomness and fuzziness. The models are applied to 12 lakes and reservoirs in China, and their eutrophic level is determined. The results show that the proposed models are effective tools for generating a set of realistic and flexible optimal solutions for complicated water quality evaluation issues. In addition, the proposed models are flexible and adaptable for diagnosing the eutrophic status.Citation: Wang, D., V. P. Singh, and Y. Zhu (2007), Hybrid fuzzy and optimal modeling for water quality evaluation, Water Resour.

Abstract-In this paper, new microstrip bandstop filters with single band, dual-band and tri-band by using U-shaped defected ground structures are presented without the assistance of coupled lines or certain resonators, and the application of DGS is developed. The proposed bandstop filters have good performances of low loss, multiband operation, transmission zeros which improve the filter frequency selectivity, and miniaturization because of the cascade of DGS and minimum defected patterns which reduce the circuit size. The new designs are demonstrated by measurement.