- The ratio of voltage to current (impedance) varies along the wire – at the ends the current is low and the voltage is high (high impedance) while at the centre the current is high and the voltage is low (low impedance)
- Feed-point impedance depends on where the feed point is. It varies from high impedance at the ends reducing to low impedance at the centre
- At the centre of a resonant half wave antenna the impedance is resistive and in free space is about 70Ω