What is the impedance at the feed point of a half-wave dipole in free space?

The theoretical feed point impedance of a resonant half-wave dipole situated in free space (infinitely far away from the ground and any other objects) is mathematically calculated to be approximately 73 ohms. In real-world amateur radio applications, a dipole is usually mounted at a finite height above the ground, which naturally lowers its feed point impedance to somewhere around 50 to 60 ohms. This makes standard 50-ohm coaxial cable an excellent match. However, exam questions specifying 'in free space' are testing your knowledge of the pure theoretical value. Distractors like 300 ohms or 450 ohms apply to other antenna types, such as folded dipoles or specific open-wire feedlines, not a standard half-wave dipole.