Which of the following factors affect the feed point impedance of an antenna?

The feed point impedance of an antenna is primarily determined by its physical dimensions, its operating frequency, and its surrounding environment. When an antenna is placed close to the earth, the ground acts as a reflector. The reflected electromagnetic wave interacts with the antenna elements, altering its radiation resistance and reactance depending on its height above the ground. Distractors such as transmission line length or antenna tuner settings affect the impedance seen at the transmitter end of the feed line, but they do not change the physical feed point impedance of the antenna itself. The input power level simply scales the voltage and current but has no effect on the inherent impedance.