Difference between flat ribbon type and rounded HDMI cables in EMI (RFI) shielding

When it comes to HDMI cables, the shape of the cable drastically changes how it handles electromagnetic interference (EMI). For radio amateurs, it is very important when you choose HDMI cables for your radio shack, often used to connect desktop computer to the monitor. The biggest difference between flat ribbon and round cables lies in their physical ability to incorporate shielding and how their internal wires are arranged.

• Round Cables (Superior Shielding): The cylindrical shape easily accommodates multiple layers of foil or braided shielding and protective fillers. Inside, the wires are configured in twisted pairs, which naturally cancels out induced noise and crosstalk. Use this geometry to protect high-speed signals in noisy environments.
• Flat Ribbon Cables (Weaker Shielding):Flat cables lay their copper wires parallel to each other, which can act like a small antenna and make them more prone to crosstalk and external EMI.Additionally, applying an overall shield to a flat cable is physically difficult because the shielding material tends to curl up rather than stay flat. Best reserved for static, tight spaces like under a carpet where EMI is low.