Extra exam question E9D02

WhyCircular polarization can be produced by arranging two linearly polarized Yagis on the same axis, perpendicular to each other, with the driven elements at the same point on the boom and fed 90 degrees out of phase. Circular polarization can be produced by arranging two linearly polarized Yagis on the same axis, physically perpendicular to each other, with both driven elements at the same point along the boom, and feeding them 90 degrees out of phase, so their combined fields rotate as they propagate, answer C. Stacking two Yagis in parallel planes, whether fed in phase or 90 degrees out of phase, or arranging them collinearly fed 180 degrees apart, don't produce this same rotating-field circular polarization effect.