If a transmission line has a characteristic impedance of 72 ohms and is cut in half, what will each half's ZO be?

The characteristic impedance of a transmission line, denoted as ZO, is determined by the physical properties of the line itself, such as its capacitance and inductance per unit length, rather than its length. When a transmission line is cut in half, the impedance of each segment does not change; it remains the same as the original line.

Thus, if the original transmission line has a characteristic impedance of 72 ohms, each half also retains this same characteristic impedance of 72 ohms, regardless of the fact that their lengths have been halved. This principle is fundamental in transmission line theory and is crucial for understanding how impedance behaves in various configurations.

Options that suggest a new impedance based on the halving of the line or require knowledge about the length to determine impedance misunderstand how characteristic impedance works. The characteristic impedance is an intrinsic property of the line relating to its design and materials, not its length.