Technician exam question T9A06

WhyA Yagi antenna offers the greatest gain among the common antenna types. A Yagi arranges multiple elements, a driven element plus directors and reflectors, to concentrate radiated energy into a tight forward lobe, giving it more gain than the simpler antennas listed, answer D. A 5/8-wave vertical (A) and J-pole (C) are both single-element designs with only modest gain over a basic dipole, and an isotropic antenna (B) is a theoretical, non-directional reference antenna with no gain at all, by definition the baseline everything else is measured against.