Why Your Signal Integrity Simulations Don’t Always Measure Up

This week on LinkedIn, I saw my friend Bert Simonovich post about the effects of anisotropy in PCB materials—and it took me right back to my days at Transline Technology, where RF/microwave engineers would frequently ask:

"Why doesn’t my board match the simulation?"

It’s a common and valid frustration. Over the years, I’ve learned from some of the best minds in the industry—like Bert, Eric Bogatin, Steve Sandler, Heidi Barnes, and John Coonrod—and I’ve picked up a lot about why simulations so often fail to match reality.

Here are just a few reasons why your simulations may not measure up:

• You’re modeling with ideal assumptions that don’t account for real-world fabrication effects.

• You're ignoring anisotropy, glass weave skew, and copper roughness.

• Your return path isn’t modeled explicitly.

• You're trusting tool defaults that prioritize speed over accuracy.

💡 Good news: there are ways to fix this and close the gap between simulation and lab bench results.

👉 Want to dive deeper? I unpack the full story—with practical tips, expert insights, and recommended resources—over on The EEcosystem Substack:

🔗 Read the full article on Substack →

Why your Simulations Don't Always Measure up