DesignForge: A Klopfenstein Taper from One Prompt

Overview:

At DesignForge AI, one prompt took a 50→90 Ω Klopfenstein taper on 0.254 mm FR4 from specification to a solved, verified Ansys HFSS model. Deterministic apps supply every number, and the orchestrator runs the toolchain. The orchestrator ran on Claude Sonnet 5.

How it works:

  • Impedance Width Calculator (deterministic app): target Z₀, εr and height in; trace width out.
  • Taper Transition Calculator (deterministic app): 50→90 Ω, ripple and length in; the width profile and the analytical S11 and S21 out.
  • Taper Builder (skill): builds and solves the taper in HFSS from the calculator widths.
  • /plot-s-parameters (skill): overlays the HFSS sweep on the analytical model.

Result: the HFSS S11 and S21 follow the analytical Klopfenstein response from 1 to 60 GHz. It took about 20 minutes end to end, simulation time included.

Taper design, end to end
From the prompt, through the deterministic calculators and skills, to the solved HFSS model and the comparison plot.
HFSS vs analytical S-parameters
HFSS (solid) against the analytical model (dashed), S11 and S21 from 1 to 60 GHz.
The taper in HFSS
The complete taper, built and solved in HFSS.

View Next

Evaluating an HFSS agent: benchmarks and an honest loss

How I evaluated an AI agent that drives Ansys HFSS. An atomic prompt suite and gold benchmarks graded against reference projects, and an A/B race between two agents on the same task.

MMIC skills and IMS 2026 demos

Agent skills that turn hours of MMIC component work in Ansys HFSS into minutes, a skill chain that built a GaAs bandpass filter end to end, and the demos from the DesignForge booth at IMS 2026.