Question T4A08
From subelement T4 - T4A
Which of the following conductors is preferred for bonding at RF?
Why is this correct?
Flat copper strap is preferred for RF bonding because it has low impedance at radio frequencies. At RF, current flows primarily on conductor surfaces (skin effect), so the wide, flat surface area of copper strap provides an excellent path. Steel wire has poor conductivity and high resistance. Twisted-pair cable creates inductance that opposes RF current. Copper braid, while conductive, has higher impedance than flat strap due to its woven structure creating small inductances between strands.
Memory tip
Remember the 'surface area rule' for RF: wider conductors with more surface area always win over narrower ones. When you see RF grounding questions, look for the option with the most surface area and shortest path - this pattern applies across many RF circuit problems.
Learn more
Proper RF bonding requires understanding skin effect - the tendency for RF current to flow on conductor surfaces rather than through the bulk material. Flat copper strap maximizes surface area while minimizing inductance, creating the lowest impedance path for RF energy. This principle applies to all RF grounding systems, from equipment bonding to tower grounding arrays. The wide, flat geometry also reduces electromagnetic field coupling between nearby conductors, improving overall system performance and reducing interference potential.
Think about it
Why do you think the geometry of a conductor becomes more important at radio frequencies compared to DC circuits?