What Yagi driven element feed point impedance is required to use a beta or hairpin matching system?
Capacitive (driven element electrically shorter than 1/2 wavelength)✓Correct answer
Inductive (driven element electrically longer than 1/2 wavelength)
Purely resistive
Purely reactive
Explanation
The hairpin is a shorted stub, which acts as a shunt inductor, and a shunt inductor can only tune out negative reactance. The driven element is therefore cut slightly shorter than resonance so its feed point impedance has the capacitive component the hairpin needs to cancel.