Ham Radio General Class Practice Test

The feed-point impedance of a half-wave dipole antenna is affected significantly by the position of the feed point. As the feed point is moved from the center toward the ends, the impedance steadily increases due to the changes in current distribution along the antenna.

In a center-fed half-wave dipole, the maximum current is present at the center of the antenna, resulting in the lowest impedance at this point because there’s high current and relatively low voltage. As you move the feed point toward one of the ends, the current decreases, and the voltage increases, which leads to a rise in impedance. This behavior continues until you reach the very end of the dipole, where the impedance reaches its maximum value.

The relationship between feed-point location and impedance is influenced by antenna theory principles, particularly as they relate to how standing waves and current distribution work on a resonant antenna. Thus, the steady increase in impedance as you move the feed point toward the end of the dipole makes it clear why this is the correct choice.