optimization of a dual band slot antenna - dynardo …2 optimization dual band slot antenna ansys...

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Example

optiSLang Optimization of a Dual Band Slot Antenna

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Optimization ● Dual Band Slot Antenna ● ANSYS HFSS

Example optiSLang © Dynardo GmbH

Problem Definition

• Minimize the return loss at desired frequencies of 2.4 and 5.8 kHz

The minima (positions) of the return loss should match the required frequencies

The amplitudes of both minima should be minimized

• 9 geometry parameters are considered for the design variation

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Task Description

• Width and length of the slot (ws, ls)

• Distances of the U-shaped conductors in the ground plane

to the boundary of the slot on x- and y-direction (gap1, gap2)

• Distance of the two conductors in the ground plane to each other (dd)

• Width of the conductors in the ground plane in x- and y-direction (w1, w2)

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• Length and width of the microstrip feed line (lf, wf)

Task Description

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ANSYS Workbench Project

• Open the ready to use Workbench project Dual_Band_Antenna.wbpz

• ANSYS HFSS (High Frequency Structural Solver) is used as solver

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Task Description

• Amplitudes at desired frequencies as well as positions and amplitudes of

the two minima are response values

• Input parameters and simulation responses appear in the parameter set

Return loss of initial design

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• Drag a new sensitivity system to the parameter set

• Specify the lower and upper ranges of the geometry parameters

Definition of the Design Variables

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Definition of the Optimization Criteria

• Sum of squared differences of calculated and desired frequencies

is used as objective to monitor the deviation in the sensitivity designs

• Constraints are not necessary

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Example optiSLang © Dynardo GmbH © Dynardo GmbH

Results of the Sensitivity Analysis

• 100 Latin Hypercube Samples are evaluated by the HFSS solver

• Some design frequencies are far away from the desired 2.4 and 5.8 kHz

• After deactivation a positive correlation can be observed in the positions,

furthermore the prognosis quality in the MOP approximations is increased

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Example optiSLang © Dynardo GmbH © Dynardo GmbH

• Positions are mostly influenced by ws and have high CoP values

• Parameters ws and lf have highest influence on minimum amplitudes

• Due to the low prognosis quality of the amplitudes,

a confident quantification of the parameter influence is not possible

All parameters are considered for the following optimization

Sensitivity Analysis using MOP

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• Positions show an almost linear behavior and have large CoP values

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• The amplitudes show an strong nonlinear behavior and have low CoP values

Optimization on the MOP might be not successful

Optimization using direct solver calls is applied in the next step

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Best Design of Sensitivity Analysis

• The best design of the Latin Hypercube Sampling shows a good

agreement of the positions of the minima with the desired values

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Best Design of Sensitivity Analysis

• The positions match much better than the initial design

• Corresponding amplitudes are not improved

Following optimization has to consider positions and amplitudes

in the objective function

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• Two terms are considered in objective function to be minimized

• Sum of squared differences of calculated and desired frequencies

• Maximum value of negative amplitudes at both minima

• Weighting is introduced by scaling the position error by 0.01 GHz

Direct Optimization

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Optimization using Direct Solver Calls

• The Adaptive Response Surface Method is suggested as optimizer

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Optimization with Adaptive Response Surfaces

• The best design matches the desired frequencies very well and has

significantly improved amplitude values

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Summary of the Optimization Results

• Sensitivity analysis found a design which serves the desired frequencies

• Unimportant parameters could not identified securely due to low CoP

values in the amplitudes values

• Optimization with direct solver calls by weighting the deviation of the

frequencies and the amplitude values could achieve a significant

improvement of the initial design

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If you have any questions on this tutorial do not hesitate to contact

[email protected]

phone +49 (0) 3643 9008-32

optimization of a dual band slot antenna - dynardo …2 optimization dual band slot antenna ansys...

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