What is a balanced transmission line composed of?

A balanced transmission line is specifically composed of two parallel wires that are designed to carry equal and opposite currents. The parallel configuration helps to minimize the electromagnetic interference and radiation effects that can arise in unbalanced lines. In a balanced line, the current flows equally on both wires, maintaining a balanced impedance and creating a magnetic field that cancels out outside interference.

This design plays a crucial role in achieving efficient transmission of signals over distances, particularly in amateur radio applications where clear communication is essential. The balance in transmission lines is important in maintaining signal integrity and reducing losses, making this option the most accurate representation of what constitutes a balanced transmission line.

The other choices do not accurately describe the characteristics of a balanced transmission line. For instance, twisted wires can help with reducing interference but do not fundamentally constitute a balanced line. Coaxial cables are inherently unbalanced due to their single central conductor surrounded by a shield, which disrupts the balance. Therefore, the definition of a balanced transmission line is best captured by the use of two parallel wires.