What is meant by the “main lobe” of a directive antenna?
The correct answer is D: The direction of maximum radiated field strength from the antenna. What is meant by the 'main lobe' of a directive antenna is the direction of maximum radiated field strength from the antenna. The main lobe is where the antenna radiates most strongly. For amateur radio operators, this is the primary radiation direction. Understanding this helps when using directional antennas.
Exam Tip
Main lobe = direction of maximum radiated field strength. Think 'M'ain 'L'obe = 'M'aximum 'L'ight (radiation) direction. The main lobe is where the antenna radiates most strongly. Not vertical angle, not maximum current, not VSWR point - just direction of maximum field strength.
Memory Aid
"Main lobe = direction of maximum radiated field strength. Think 'M'ain 'L'obe = 'M'aximum 'L'ight direction. The main lobe is where the antenna radiates most strongly. Primary radiation direction of directive antennas."
Real-World Application
A directive antenna (like a Yagi): The main lobe is the direction where the antenna radiates most strongly (maximum field strength). For a Yagi pointing east, the main lobe is toward the east - that's where maximum radiation occurs. This is the primary radiation direction - the main lobe.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Main lobe isn't maximum vertical angle of radiation - it's the direction of maximum field strength, not just angle. Vertical angle isn't the definition.
Option B: Incorrect. Main lobe isn't point of maximum current - current and radiation pattern are different. Maximum current isn't the main lobe.
Option C: Incorrect. Main lobe isn't maximum voltage standing wave point - VSWR and radiation pattern are different. VSWR point isn't the main lobe.
题目解析
The correct answer is D: The direction of maximum radiated field strength from the antenna. What is meant by the 'main lobe' of a directive antenna is the direction of maximum radiated field strength from the antenna. The main lobe is where the antenna radiates most strongly. For amateur radio operators, this is the primary radiation direction. Understanding this helps when using directional antennas.
考试技巧
Main lobe = direction of maximum radiated field strength. Think 'M'ain 'L'obe = 'M'aximum 'L'ight (radiation) direction. The main lobe is where the antenna radiates most strongly. Not vertical angle, not maximum current, not VSWR point - just direction of maximum field strength.
记忆口诀
Main lobe = direction of maximum radiated field strength. Think 'M'ain 'L'obe = 'M'aximum 'L'ight direction. The main lobe is where the antenna radiates most strongly. Primary radiation direction of directive antennas.
实际应用示例
A directive antenna (like a Yagi): The main lobe is the direction where the antenna radiates most strongly (maximum field strength). For a Yagi pointing east, the main lobe is toward the east - that's where maximum radiation occurs. This is the primary radiation direction - the main lobe.
错误选项分析
Option A: Incorrect. Main lobe isn't maximum vertical angle of radiation - it's the direction of maximum field strength, not just angle. Vertical angle isn't the definition. Option B: Incorrect. Main lobe isn't point of maximum current - current and radiation pattern are different. Maximum current isn't the main lobe. Option C: Incorrect. Main lobe isn't maximum voltage standing wave point - VSWR and radiation pattern are different. VSWR point isn't the main lobe.
知识点
Main lobe, Directive antenna, Maximum radiated field strength, Direction
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.