What does impedance mean for antennas?

Antenna impedance refers to the resistance that the antenna presents to alternating current at its frequency and is a measure of the relationship between voltage and current at a particular point on the antenna. It is expressed in ohms. A good impedance match between the antenna and the connected radio transmitter or receiver is crucial to ensure effective transmission and the best possible reception, as it minimizes power losses. Common impedance values are 50 ohms for coaxial cable connections.