Deep Dive: T9A10
The correct answer is D: Broadside to the antenna. A half-wave dipole antenna radiates the strongest signal broadside to the antenna (perpendicular to the antenna wire). The radiation pattern of a dipole is a figure-8 shape, with maximum radiation at right angles to the wire and minimum radiation off the ends. For amateur radio operators, understanding dipole radiation patterns helps when orienting antennas for maximum signal in desired directions. A horizontal dipole provides best coverage to the sides (broadside), not off the ends. This knowledge is essential for antenna placement and orientation.
Why Other Answers Are Wrong
Option A: Incorrect. A dipole doesn't radiate equally in all directions - that's an isotropic antenna. A dipole has a directional pattern with maximum broadside and minimum off the ends. Option B: Incorrect. A dipole radiates weakest off the ends, not strongest. The ends are the null points in the radiation pattern. Option C: Incorrect. Radiation direction isn't related to feed line direction - it's related to antenna orientation. The feed line doesn't affect the radiation pattern.
Exam Tip
Dipole = strongest broadside (perpendicular to wire). Think 'D'ipole = 'D'irection is 'B'roadside. Maximum radiation at right angles to the wire, minimum off the ends. Not omnidirectional, not off ends, not toward feed line.
Memory Aid
Dipole = strongest broadside. Think 'D'ipole = 'D'irection is 'B'roadside (perpendicular to wire). Maximum radiation at right angles, minimum off the ends. Figure-8 pattern.
Real-World Example
You install a 20-meter dipole running east-west. The antenna radiates strongest to the north and south (broadside to the wire), giving you best coverage in those directions. Signals to the east and west (off the ends) are much weaker. If you want to work Europe, you'd orient the dipole north-south so it radiates broadside toward Europe.
Source & Coverage
Question Pool: 2022-2026 Question Pool
Subelement: T9A
Reference: 2022-2026 Question Pool · T9 - Antennas and feed lines
Key Concepts
Verified Content
Question from the official FCC Technician Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the T9A topic.