How to Use HarnessFlow

We have several wire harness examples ready for you to try. Just follow these steps:

1. Click the Examples button to browse available harness configurations.
2. Choose a harness example. We recommend Option 4: Shielded Twisted Pair to start.
3. Click the Run button to simulate. This calculates the capacitance and inductance matrices.
4. Click the Export Model button to generate and download an S-parameter model. You can import this into any commercial signal integrity tool such as HyperLynx or ADS.
   Note: Refer to the model drawing for pin references. If you prefer to use PSpice, check out the EMI Sleuth S-parameter to PSpice Converter Tool.

What Is HarnessFlow?

HarnessFlow is a simulation tool built specifically for electromagnetic analysis of electrical wire harnesses. It is designed for engineers working in aerospace, military, automotive, and industrial applications.

What Does HarnessFlow Do?

HarnessFlow calculates key electrical parameters of wire harnesses, including:

• Capacitance and inductance
• Dielectric conductance losses
• Radiation resistance
• Series wire resistance
• Skin effect
• Shield transfer impedance

The secret sauce, and what makes HarnessFlow so useful, is that it also generates an S-parameter model that can be dropped straight into a circuit simulation. This model is valid over the frequency range and harness length that you specify. This makes simulating harness coupling effects trival.

How Accurate Is It?

Verification testing shows capacitance results within 1% of analytical equations. Capacitance is computed using the Method of Moments (MoM), a trusted technique in computational electromagnetics. Inductance is derived from the multiconductor transmission line (MTL) capacitance matrix using a TEM mode assumption in free space.

Other parameters such as resistance, dielectric losses, and shield impedance are calculated using analytical approximations. This hybrid approach provides fast simulations with reliable accuracy.

Formal validation reports are in progress and will be presented at upcoming IEEE conferences. These reports will detail the accuracy of S-parameter models for circular connectors used in space system testing. Early results show strong agreement with RF coax cable behavior in terms of propagation, loss, and shield leakage.

If you have a specific application you would like to validate, feel free to reach out: russell@emisleuth.com

Goals and Future Plans

HarnessFlow is free to use and will remain free as long as server load stays manageable. It is built on an open-source project called PyCoupling, which was started in 2021. Eventually, the full package will be released so you can run it locally or in a secure environment.

I am working hard to build a practical tool for engineers solving real-world signal integrity and electromagnetic compatibility problems, especially for those who do not have the budget for traditional and expensive simulation software.