Why do most two-element Yagis with normal spacing have a reflector instead of a director?

Erklärung

At the element spacings normally used in a two-element beam, roughly 0.15 to 0.2 wavelength, a parasitic element tuned slightly longer than the driven element and acting as a reflector yields more forward gain than a director at the same spacing. It is also less sensitive to exact length and spacing.