How Many Ferrite Beads on an HF Antenna? What is Coaxial Cable? What are Common Mode Currents?

Six second delay at the beginning. Title was edited down to fit the number of characters. Jim W6LG uses a device similar to that manufactured by Mark Smith at www.halibut.electronics.com. Jim has ordered that circuit board and will test it soon in a YouTube video. How many conductors are there in a typical coax cable? Where do common mode currents flow?