What is an advantage of vertically stacking horizontally polarized Yagi antennas?
The correct answer is D: It narrows the main lobe in elevation. An advantage of vertically stacking horizontally polarized Yagi antennas is that it narrows the main lobe in elevation. Stacking reduces the vertical beamwidth, concentrating energy in a narrower elevation angle. For amateur radio operators, this improves long-distance communication. Understanding this helps when designing antenna arrays.
Exam Tip
Vertically stacked Yagis advantage = narrows main lobe in elevation. Think 'V'ertically 'S'tacked = 'V'ertical 'S'eparation = 'N'arrows 'E'levation. Stacking reduces vertical beamwidth, concentrating energy in narrower elevation angle. Not polarization selection, not dual polarization, not azimuth - just elevation narrowing.
Memory Aid
"Vertically stacked Yagis advantage = narrows main lobe in elevation. Think 'V'ertically 'S'tacked = 'N'arrows 'E'levation. Stacking reduces vertical beamwidth, concentrating energy in narrower elevation angle. Improves long-distance communication."
Real-World Application
Two horizontally polarized Yagis stacked vertically: The vertical separation creates a narrower elevation pattern. Instead of a wide elevation beam, you get a narrower beam that concentrates energy at a specific elevation angle. This is ideal for long-distance communication - the narrower elevation beam improves performance. This is the advantage - narrows main lobe in elevation.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Stacking doesn't allow quick selection of vertical or horizontal polarization - stacking is for elevation pattern, not polarization selection. Polarization selection isn't the advantage.
Option B: Incorrect. Stacking doesn't allow simultaneous vertical and horizontal polarization - stacking is for elevation pattern, not dual polarization. Dual polarization isn't the advantage.
Option C: Incorrect. Stacking doesn't narrow the main lobe in azimuth - it narrows in elevation, not azimuth. Azimuth narrowing isn't the advantage.
题目解析
The correct answer is D: It narrows the main lobe in elevation. An advantage of vertically stacking horizontally polarized Yagi antennas is that it narrows the main lobe in elevation. Stacking reduces the vertical beamwidth, concentrating energy in a narrower elevation angle. For amateur radio operators, this improves long-distance communication. Understanding this helps when designing antenna arrays.
考试技巧
Vertically stacked Yagis advantage = narrows main lobe in elevation. Think 'V'ertically 'S'tacked = 'V'ertical 'S'eparation = 'N'arrows 'E'levation. Stacking reduces vertical beamwidth, concentrating energy in narrower elevation angle. Not polarization selection, not dual polarization, not azimuth - just elevation narrowing.
记忆口诀
Vertically stacked Yagis advantage = narrows main lobe in elevation. Think 'V'ertically 'S'tacked = 'N'arrows 'E'levation. Stacking reduces vertical beamwidth, concentrating energy in narrower elevation angle. Improves long-distance communication.
实际应用示例
Two horizontally polarized Yagis stacked vertically: The vertical separation creates a narrower elevation pattern. Instead of a wide elevation beam, you get a narrower beam that concentrates energy at a specific elevation angle. This is ideal for long-distance communication - the narrower elevation beam improves performance. This is the advantage - narrows main lobe in elevation.
错误选项分析
Option A: Incorrect. Stacking doesn't allow quick selection of vertical or horizontal polarization - stacking is for elevation pattern, not polarization selection. Polarization selection isn't the advantage. Option B: Incorrect. Stacking doesn't allow simultaneous vertical and horizontal polarization - stacking is for elevation pattern, not dual polarization. Dual polarization isn't the advantage. Option C: Incorrect. Stacking doesn't narrow the main lobe in azimuth - it narrows in elevation, not azimuth. Azimuth narrowing isn't the advantage.
知识点
Vertically stacked Yagis, Horizontally polarized, Narrows main lobe, Elevation
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.