What is one effect of increasing the boom length and adding directors to a Yagi antenna?

A Yagi antenna achieves its directional properties by combining a driven element with parasitic elements (reflectors and directors). Adding more directors and increasing the length of the boom focuses the radiated RF energy into a tighter, more concentrated beam in the forward direction. Because the total amount of radiated power remains the same, focusing it into a narrower path results in an increase in forward gain. This allows you to punch through interference and reach more distant stations. Adding directors actually narrows the beamwidth, making the 'Beamwidth increases' option incorrect. Furthermore, power handling is determined by the physical components and feedline, not the number of directors, and the front-to-back ratio is primarily controlled by the reflector design rather than simply stacking multiple directors.