The Experts below are selected from a list of 10251 Experts worldwide ranked by ideXlab platform

J W Bandler - One of the best experts on this subject based on the ideXlab platform.

  • cognition driven formulation of space mapping for equal ripple optimization of Microwave Filters
    IEEE Transactions on Microwave Theory and Techniques, 2015
    Co-Authors: Chao Zhang, Feng Feng, Qijun Zhang, Venumadhavreddy Gongalreddy, J W Bandler
    Abstract:

    Space mapping is a recognized method for speeding up electromagnetic (EM) optimization. Existing space-mapping approaches belong to the class of surrogate-based optimization methods. This paper proposes a cognition-driven formulation of space mapping that does not require explicit surrogates. The proposed method is applied to EM-based filter optimization. The new technique utilizes two sets of intermediate feature space parameters, including feature frequency parameters and ripple height parameters. The design variables are mapped to the feature frequency parameters, which are further mapped to the ripple height parameters. By formulating the cognition-driven optimization directly in the feature space, our method increases optimization efficiency and the ability to avoid being trapped in local minima. The technique is suitable for design of Filters with equal-ripple responses. It is illustrated by two Microwave filter examples.

  • electromagnetic design of high temperature superconducting Microwave Filters
    International Journal of Microwave and Millimeter-wave Computer-aided Engineering, 1995
    Co-Authors: J W Bandler, C Moskowitz, R M Biernacki, S H Chen, William J Getsinger, P A Grobelny, S H Talisa
    Abstract:

    We present novel approaches to electromagnetic design of high-temperature superconducting (HTS) quarter-wave parallel coupled-line microstrip Filters. The desired narrow bandwidths (less than 2%) coupled with the large dielectric constant of substrate materials used in the HTS technology (er ≈ 24) make the design problems difficult to treat accurately for many traditional Microwave circuit design software packages with analytical/empirical models. We have successfully performed an HTS filter design with accurate electromagnetic field simulations. We discuss problems related to electromagnetic design of such Filters. We describe a look-up table method and a powerful space mapping optimization technique, which dramatically reduce the CPU time needed in the design process. Finally, we address the issue of improved modeling of the HTS filter using analytical/empirical models. © 1995 John Wiley & Sons, Inc.

  • electromagnetic design of high temperature superconducting Microwave Filters
    International Microwave Symposium, 1994
    Co-Authors: J W Bandler, C Moskowitz, R M Biernacki, S H Chen, P A Grobelny, S H Talisa
    Abstract:

    We present novel approaches to electromagnetic design of high-temperature superconducting quarter-wave parallel coupled-line microstrip Filters. The dielectric constant of substrate materials used in high-temperature superconductor technology is too large to be accurately treated by traditional Microwave circuit design software packages with analytical/empirical models. We employ electromagnetic field simulation and develop a look-up table method and a powerful space mapping optimization technique, which dramatically reduce the CPU time for the design process. >

S H Talisa - One of the best experts on this subject based on the ideXlab platform.

  • electromagnetic design of high temperature superconducting Microwave Filters
    International Journal of Microwave and Millimeter-wave Computer-aided Engineering, 1995
    Co-Authors: J W Bandler, C Moskowitz, R M Biernacki, S H Chen, William J Getsinger, P A Grobelny, S H Talisa
    Abstract:

    We present novel approaches to electromagnetic design of high-temperature superconducting (HTS) quarter-wave parallel coupled-line microstrip Filters. The desired narrow bandwidths (less than 2%) coupled with the large dielectric constant of substrate materials used in the HTS technology (er ≈ 24) make the design problems difficult to treat accurately for many traditional Microwave circuit design software packages with analytical/empirical models. We have successfully performed an HTS filter design with accurate electromagnetic field simulations. We discuss problems related to electromagnetic design of such Filters. We describe a look-up table method and a powerful space mapping optimization technique, which dramatically reduce the CPU time needed in the design process. Finally, we address the issue of improved modeling of the HTS filter using analytical/empirical models. © 1995 John Wiley & Sons, Inc.

  • electromagnetic design of high temperature superconducting Microwave Filters
    International Microwave Symposium, 1994
    Co-Authors: J W Bandler, C Moskowitz, R M Biernacki, S H Chen, P A Grobelny, S H Talisa
    Abstract:

    We present novel approaches to electromagnetic design of high-temperature superconducting quarter-wave parallel coupled-line microstrip Filters. The dielectric constant of substrate materials used in high-temperature superconductor technology is too large to be accurately treated by traditional Microwave circuit design software packages with analytical/empirical models. We employ electromagnetic field simulation and develop a look-up table method and a powerful space mapping optimization technique, which dramatically reduce the CPU time for the design process. >

  • low and high temperature superconducting Microwave Filters
    IEEE Transactions on Microwave Theory and Techniques, 1991
    Co-Authors: S H Talisa, M A Janocko, C Moskowitz, J Talvacchio, J F Billing, R Brown, D C Buck, C K Jones, Bruce R Mcavoy, G R Wagner
    Abstract:

    Stripline and microstrip Filters at X-band were designed and fabricated using low- and high-temperature superconductors in quarter-wave, parallel-coupled section configurations. Low-temperature superconducting niobium thin films, deposited on single-crystal sapphire, were used to build to six-pole stripline Filters with adjacent passbands and approximately 3 dB crossovers and 1.2% bandwidth. Four- and six-pole microstrip Filters were made with in situ epitaxial YBa/sub 2/Cu/sub 3/O/sub 7/ (YBCO) films on LaAlO/sub 3/ substrates. All the YBCO Filters showed 77 K passbands with clean skirts and high out-of-band rejection. The six-pole Filters had adjacent passbands with -28 dB crossovers and 1.5% bandwidth. >

M J Lancaster - One of the best experts on this subject based on the ideXlab platform.

  • global optimization of Microwave Filters based on a surrogate model assisted evolutionary algorithm
    IEEE Transactions on Microwave Theory and Techniques, 2017
    Co-Authors: Bo Liu, Hao Yang, M J Lancaster
    Abstract:

    Local optimization is a routine approach for full-wave optimization of Microwave Filters. For filter optimization problems with numerous local optima or where the initial design is not near to the optimal region, the success rate of the routine method may not be high. Traditional global optimization techniques have a high success rate for such problems, but are often prohibitively computationally expensive considering the cost of full-wave electromagnetic simulations. To address the above challenge, a new method, called surrogate model-assisted evolutionary algorithm for filter optimization (SMEAFO), is proposed. In SMEAFO, considering the characteristics of filter design landscapes, Gaussian process surrogate modeling, differential evolution operators, and Gaussian local search are organized in a particular way to balance the exploration ability and the surrogate model quality, so as to obtain high-quality results in an efficient manner. The performance of SMEAFO is demonstrated by two real-world design cases (a waveguide filter and a microstrip filter), which do not appear to be solvable by popular local optimization techniques. Experiments show that SMEAFO obtains high-quality designs comparable with global optimization techniques but within a reasonable amount of time. Moreover, SMEAFO is not restricted by certain types of Filters or responses. The SMEAFO-based filter design optimization tool can be downloaded from http://fde.cadescenter.com .

  • synthesis of multiple output coupled resonator circuits using coupling matrix optimisation
    Iet Microwaves Antennas & Propagation, 2011
    Co-Authors: Talal Skaik, M J Lancaster, F Huang
    Abstract:

    Coupled resonator circuits are the basis for the design of many bandpass Microwave Filters. Design techniques used for two-port coupled resonator circuits are extended here to multiple output circuits such as power dividers and diplexers. The design approach is based on synthesis of coupling matrix for multiple coupled resonators with multiple outputs using gradient-based optimisation. It allows the synthesis of power dividers with arbitrary power division, as well as diplexers and multiplexers with novel topologies. Since there is no need to use separate energy distribution networks such as circulators, manifolds or other junctions, the components can be miniaturised. An X-band unequal power divider and diplexer have been designed and realised using waveguide cavity resonators to confirm the new design methodology.

  • tunable Microwave Filters based on discrete ferroelectric and semiconductor varactors
    Iet Microwaves Antennas & Propagation, 2011
    Co-Authors: X Wang, Peng Bao, T J Jackson, M J Lancaster
    Abstract:

    This study presents a direct comparison between semiconductor and barium strontium titanate (BST) tuning technologies. Tapped line combline two-pole and four-pole bandpass Filters were designed in a coplanar waveguide configuration. Discrete BST interdigital capacitors were fabricated and integrated into the filter circuits in a hybrid manner. The BST varactors performed as tuning elements in the Filters. The same filter was also made using gallium arsenide (GaAs) varactors and the tuning and loss performance were compared with the BST Filters. The centre frequency of the two-pole BST filter tuned 30.3% from 1.55 to 2.02 GHz with insertion loss ranging from 3.7 to 1.1 dB, at an electric field of 6.5 V/mu m. This filter has a figure of merit of 0.87 dB(-1). The two-pole GaAs filter showed a wide tuning range from 0.94 to 2.44 GHz at 14 V with insertion loss ranging from 4.2 to 0.8 dB. The results are discussed in detail, as it is important to clarify the comparison with relation to the quality of the materials, as well as the particular filter designs and centre frequencies involved.

  • coupling matrix synthesis of cross coupled Microwave Filters using a hybrid optimisation algorithm
    Iet Microwaves Antennas & Propagation, 2009
    Co-Authors: Gemma Nicholson, M J Lancaster
    Abstract:

    A hybrid optimisation algorithm that synthesises coupling matrices for cross-coupled Microwave Filters is presented. A binary encoded genetic algorithm is combined at regular intervals with a sequential quadratic programming local search method to form a hybrid, exploiting the speed of the local search, while maintaining diversity with the genetic algorithm. The genetic algorithm uses the stochastic uniform selection technique and a multiple point crossover operator. A compact, efficient cost function requiring only the determinant and a cofactor of the coupling matrix is used as the basis of the optimisation algorithm. Optimisation algorithms simplify the process of synthesising coupling matrices, compared with analytical synthesis. However, algorithms that use only local search methods cannot be guaranteed to find a global minimum. This hybrid method aims to extend the range of coupling matrices that can be synthesised by optimisation, while maintaining the speed of search. A coupling matrix for a tenth order coupling matrix for a dual band symmetric filter and a seventh order asymmetric filter are synthesised to verify the method.

  • air filled square coaxial transmission line and its use in Microwave Filters
    IEE Proceedings - Microwaves Antennas and Propagation, 2005
    Co-Authors: Ignacio Llamasgarro, M J Lancaster, Peter Hall
    Abstract:

    A suspended coaxial transmission line with an air propagation medium is presented. The transmission line is made only of metal, thereby avoiding dielectric and radiation losses. Short-circuit stubs suspend the centre conductor of the coaxial structure which is used in the design of two dual-mode narrowband Microwave Filters. Stacked layers of copper sheets are used to form the square coaxial transmission line, which has low loss and low dispersion.

G R Wagner - One of the best experts on this subject based on the ideXlab platform.

  • low and high temperature superconducting Microwave Filters
    IEEE Transactions on Microwave Theory and Techniques, 1991
    Co-Authors: S H Talisa, M A Janocko, C Moskowitz, J Talvacchio, J F Billing, R Brown, D C Buck, C K Jones, Bruce R Mcavoy, G R Wagner
    Abstract:

    Stripline and microstrip Filters at X-band were designed and fabricated using low- and high-temperature superconductors in quarter-wave, parallel-coupled section configurations. Low-temperature superconducting niobium thin films, deposited on single-crystal sapphire, were used to build to six-pole stripline Filters with adjacent passbands and approximately 3 dB crossovers and 1.2% bandwidth. Four- and six-pole microstrip Filters were made with in situ epitaxial YBa/sub 2/Cu/sub 3/O/sub 7/ (YBCO) films on LaAlO/sub 3/ substrates. All the YBCO Filters showed 77 K passbands with clean skirts and high out-of-band rejection. The six-pole Filters had adjacent passbands with -28 dB crossovers and 1.5% bandwidth. >

G L Heyshipton - One of the best experts on this subject based on the ideXlab platform.

  • concerning the use of high temperature superconductivity in planar Microwave Filters
    IEEE Transactions on Microwave Theory and Techniques, 1994
    Co-Authors: G L Matthaei, G L Heyshipton
    Abstract:

    The fundamentals of high-temperature superconductivity (HTS), as they apply to planar Microwave Filters, are briefly outlined. It is seen that some problems which are not usually prominent in the design of planar Microwave Filters come to the fore in the HTS case, and some of these problems are discussed. These problems include: preventing fields from impinging on normal conductor housings or radiating, reducing forward-coupling effects in order to permit the use of smaller substrates, coupling between the desired circuit mode and undesired housing waveguide-type modes, and estimating the maximum power that an HTS filter can handle without significant nonlinear effects. >