What is the radiation pattern of a dipole antenna in free space in a plane containing the conductor?
The correct answer is A: It is a figure-eight at right angles to the antenna. The radiation pattern of a dipole antenna in free space in a plane containing the conductor is a figure-eight at right angles to the antenna. A dipole has maximum radiation broadside (perpendicular) to the wire and minimum radiation off the ends, creating a figure-8 pattern. For amateur radio operators, this is fundamental dipole theory. Understanding this helps when using dipole antennas.
Exam Tip
Dipole pattern in plane = figure-eight at right angles to antenna. Think 'D'ipole = 'D'irectional = 'F'igure-'8' 'B'roadside. Dipole has maximum radiation broadside (perpendicular) to wire, minimum off ends. Not off ends, not circle, not asymmetric - just figure-8 broadside.
Memory Aid
"Dipole pattern in plane = figure-eight at right angles to antenna. Think 'D'ipole = 'F'igure-'8' 'B'roadside. Dipole has maximum radiation broadside (perpendicular) to wire, minimum off ends. Fundamental dipole pattern."
Real-World Application
A dipole antenna in free space: In the plane containing the conductor, the radiation pattern is a figure-8. Maximum radiation is at right angles (broadside) to the wire, minimum radiation is off the ends. This creates the classic figure-8 pattern. This is fundamental dipole theory - figure-8 pattern at right angles to the antenna.
Key Concepts
Why Other Options Are Wrong
Option B: Incorrect. Figure-eight off both ends is wrong - the figure-8 is at right angles (broadside), not off the ends. Off ends is minimum, not figure-8.
Option C: Incorrect. Circle (equal in all directions) is for vertical antennas, not dipoles - dipoles have directional pattern. Circle is wrong.
Option D: Incorrect. Pair of lobes on one side and single lobe on other is wrong - dipoles have symmetric figure-8 pattern. Asymmetric pattern is wrong.
题目解析
The correct answer is A: It is a figure-eight at right angles to the antenna. The radiation pattern of a dipole antenna in free space in a plane containing the conductor is a figure-eight at right angles to the antenna. A dipole has maximum radiation broadside (perpendicular) to the wire and minimum radiation off the ends, creating a figure-8 pattern. For amateur radio operators, this is fundamental dipole theory. Understanding this helps when using dipole antennas.
考试技巧
Dipole pattern in plane = figure-eight at right angles to antenna. Think 'D'ipole = 'D'irectional = 'F'igure-'8' 'B'roadside. Dipole has maximum radiation broadside (perpendicular) to wire, minimum off ends. Not off ends, not circle, not asymmetric - just figure-8 broadside.
记忆口诀
Dipole pattern in plane = figure-eight at right angles to antenna. Think 'D'ipole = 'F'igure-'8' 'B'roadside. Dipole has maximum radiation broadside (perpendicular) to wire, minimum off ends. Fundamental dipole pattern.
实际应用示例
A dipole antenna in free space: In the plane containing the conductor, the radiation pattern is a figure-8. Maximum radiation is at right angles (broadside) to the wire, minimum radiation is off the ends. This creates the classic figure-8 pattern. This is fundamental dipole theory - figure-8 pattern at right angles to the antenna.
错误选项分析
Option B: Incorrect. Figure-eight off both ends is wrong - the figure-8 is at right angles (broadside), not off the ends. Off ends is minimum, not figure-8. Option C: Incorrect. Circle (equal in all directions) is for vertical antennas, not dipoles - dipoles have directional pattern. Circle is wrong. Option D: Incorrect. Pair of lobes on one side and single lobe on other is wrong - dipoles have symmetric figure-8 pattern. Asymmetric pattern is wrong.
知识点
Dipole antenna, Radiation pattern, Figure-eight, Right angles to antenna
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.