Which of the following conductors is preferred for bonding at RF?

At radio frequencies (RF), current tends to flow only along the very outer surface of a conductor. This phenomenon is known as the "skin effect." Because of this, the best conductor for RF bonding is one that maximizes surface area. A flat copper strap has a massive surface area relative to its overall cross-section, providing a much lower impedance path for RF currents compared to standard round wire. This ensures all pieces of equipment in the shack remain safely at the same RF potential. While copper braid removed from coaxial cable also has a large surface area, it can deteriorate, trap moisture, and cause erratic noise from the individual woven strands oxidizing and rubbing together. Therefore, solid flat copper strap is always the preferred choice.