In which direction does a half-wave dipole antenna radiate the strongest signal?
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.
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 Application
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.
Key Concepts
Why Other Options 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.
题目解析
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.
考试技巧
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.
记忆口诀
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.
实际应用示例
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.
错误选项分析
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.
知识点
Dipole radiation pattern, Broadside radiation, Antenna orientation, Radiation patterns
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.