Extra exam question E9D07

WhyTop loading an electrically short HF vertical antenna improves its radiation efficiency. Top loading an electrically short HF vertical improves its radiation efficiency, since moving the loading toward the top of the antenna, where current would otherwise already be tapering off, keeps more of the antenna's current distribution higher up where it contributes more effectively to far-field radiation, answer D. It doesn't lower Q, doesn't provide greater structural strength, and doesn't cause higher losses, top loading is specifically an efficiency-improving technique, not a structural or lossy one.