Accelerated simulation‐driven design optimisation of compact couplers by means of two‐level space mapping

Int J RF Microw Comput Aided Eng

2017

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In this article, fast design closure of microwave components using feature‐based optimization (FBO) and adjoint sensitivities is discussed. FBO is one of the most recent optimization techniques that exploits a particular structure of the system response to “flatten” the functional landscape handled during the optimization process, which leads to reducing its computational complexity. When combined with gradient‐based search involving adjoint sensitivities, the design cost becomes even lower, allowing us to find the optimum design using just a few electromagnetic (EM) simulations of the structure at hand. Here, operation and performance of the algorithm is demonstrated using a waveguide filter and a miniaturized microstrip rat‐race coupler (RRC). Comparative studies indicate considerable savings that can be achieved even compared with adjoint‐based gradient search. In case of RRC, numerical results are supported by experimental validation.

Section: Case Studiesmentioning

confidence: 98%

Rapid design closure of microwave components by means of feature-based optimization and adjoint sensitivities

Int J RF Microw Comput Aided Eng

2017

Self Cite

“…A recommended approach is automated design through simultaneous numerical optimization of all relevant geometry parameters. However, conventional optimization algorithms may be impractical due to excessive computational cost . Design speedup can be obtained using surrogate‐based optimization (SBO) .…”

Section: Introductionmentioning

confidence: 99%

“…However, conventional optimization algorithms may be impractical due to excessive computational cost . Design speedup can be obtained using surrogate‐based optimization (SBO) . One of the most popular SBO methods in microwave engineering is space mapping (SM) .…”

Section: Introductionmentioning

confidence: 99%

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Low-cost multiband compact branch-line coupler design using response features and automated EM model fidelity adjustment

Int J RF Microw Comput Aided Eng

2017

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Design closure of compact microwave components is a challenging problem because of significant electromagnetic (EM) cross‐couplings in densely arranged layouts. A separate issue is a large number of designable parameters resulting from replacement of conventional transmission line sections by compact microstrip resonant cells. This increases complexity of the design optimization problem and requires employment of expensive high‐fidelity EM analysis for reliable performance evaluation of the structure at hand. Consequently, neither conventional numerical optimization algorithms nor interactive approaches (e.g., experience‐driven parameters sweeps) are capable of identifying optimum designs in reasonable timeframes. Here, we discuss application of feature‐based optimization for fast design optimization of dual‐ and multiband compact couplers. On one hand, design of such components is difficult because of multiple objectives (achieving equal power split and good matching and port isolation for all frequency bands of interest). On the other hand, because of well‐defined shapes of the S‐parameter responses for this class of components, feature‐based optimization seems to be well suited to control multiple figures of interest as demonstrated in this work. Two‐level EM modeling is used for further design cost reduction. More importantly, we develop a procedure for automated determination of the low‐fidelity EM model coarseness that allows us to find the fastest possible model that still ensures sufficient correlation with its high‐fidelity counterpart, which is critical for robustness of the optimization process. Our approach is illustrated using two dual‐band compact couplers. Experimental validation is also provided.

“…Reliable evaluation of such structures requires full‐wave EM analysis , which becomes a challenge for the design process. Another issue is increased number of geometry parameters: as opposed to a TL described by two dimensions, a typical CMRC is described by four to six variables . Clearly, traditional design approaches largely based on parameter sweeps are of limited applicability here because of their inability of handling multiple parameters .…”

Section: Introductionmentioning

confidence: 99%

Surrogate modeling for expedited two-objective geometry scaling of miniaturized microwave passives

Int J RF and Microwave Comp Aid Eng

2016

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Geometry scaling of compact microwave structures is a challenging problem because of complex relationships between the physical dimensions of the circuit and its electrical characteristics, which is mostly caused by considerable cross-couplings in densely arranged layouts. Yet, possibility of rapid redesign of a structure for various sets of design specification is important from practical point of view. In this article, we develop a procedure for expedited dimension scaling of compact microwave couplers with respect to two independent criteria. Our approach exploits inverse surrogates constructed at the level of equivalent circuit model and correction techniques that permits low-cost re-design of the coupler structure (at the level of EM-simulation model) for a required operating frequency and power split ratio. The procedure is demonstrated using a folded microstrip rat-race coupler. The scaling range for the considered example is from 0.5 to 2.0 GHz for the operating frequency, and from 26 dB to 0 dB for the power split ratio. V C 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 00:000-000, 2016.