Which of the following is used to determine if an antenna is resonant at the desired operating frequency?
The correct answer is B: An antenna analyzer. An antenna analyzer is used to determine if an antenna is resonant at the desired operating frequency. Antenna analyzers measure impedance, SWR, and resonance characteristics across a frequency range, allowing you to see exactly where your antenna resonates and how its impedance changes with frequency. For amateur radio operators, antenna analyzers are essential tools for tuning antennas, checking resonance, measuring impedance, and optimizing antenna performance. They're more convenient and accurate than using an SWR meter with a transmitter, as they can sweep frequencies and show resonance curves.
Exam Tip
Antenna analyzer = measures antenna resonance. Think 'A'ntenna 'A'nalyzer = 'A'nalyzes 'A'ntenna resonance. It measures impedance and SWR across frequencies to find resonance. Other instruments measure voltage, Q, or frequency, not antenna characteristics.
Memory Aid
"Antenna analyzer = Analyzes antenna resonance. Think 'A'ntenna 'A'nalyzer = 'A'nalyzes 'A'ntenna characteristics. Measures impedance and SWR to find resonance."
Real-World Application
You've built a 2-meter dipole and want to know if it's resonant at 146 MHz. You connect an antenna analyzer and sweep from 140-150 MHz. The analyzer shows the antenna's impedance and SWR at each frequency, clearly indicating that it resonates at 146.2 MHz with an SWR of 1.2:1. This tells you the antenna is close but needs slight adjustment to be exactly on 146 MHz.
Key Concepts
Why Other Options Are Wrong
Option A (VTVM): Incorrect. A VTVM (Vacuum Tube Voltmeter) measures voltage, not antenna resonance. It's a basic test instrument, not an antenna measurement tool.
Option C (Q meter): Incorrect. A Q meter measures the Q (quality factor) of resonant circuits but isn't specifically designed for antenna resonance measurement. Antenna analyzers are more appropriate.
Option D (Frequency counter): Incorrect. A frequency counter measures signal frequency but doesn't measure antenna resonance or impedance. It just counts frequency.
题目解析
The correct answer is B: An antenna analyzer. An antenna analyzer is used to determine if an antenna is resonant at the desired operating frequency. Antenna analyzers measure impedance, SWR, and resonance characteristics across a frequency range, allowing you to see exactly where your antenna resonates and how its impedance changes with frequency. For amateur radio operators, antenna analyzers are essential tools for tuning antennas, checking resonance, measuring impedance, and optimizing antenna performance. They're more convenient and accurate than using an SWR meter with a transmitter, as they can sweep frequencies and show resonance curves.
考试技巧
Antenna analyzer = measures antenna resonance. Think 'A'ntenna 'A'nalyzer = 'A'nalyzes 'A'ntenna resonance. It measures impedance and SWR across frequencies to find resonance. Other instruments measure voltage, Q, or frequency, not antenna characteristics.
记忆口诀
Antenna analyzer = Analyzes antenna resonance. Think 'A'ntenna 'A'nalyzer = 'A'nalyzes 'A'ntenna characteristics. Measures impedance and SWR to find resonance.
实际应用示例
You've built a 2-meter dipole and want to know if it's resonant at 146 MHz. You connect an antenna analyzer and sweep from 140-150 MHz. The analyzer shows the antenna's impedance and SWR at each frequency, clearly indicating that it resonates at 146.2 MHz with an SWR of 1.2:1. This tells you the antenna is close but needs slight adjustment to be exactly on 146 MHz.
错误选项分析
Option A (VTVM): Incorrect. A VTVM (Vacuum Tube Voltmeter) measures voltage, not antenna resonance. It's a basic test instrument, not an antenna measurement tool. Option C (Q meter): Incorrect. A Q meter measures the Q (quality factor) of resonant circuits but isn't specifically designed for antenna resonance measurement. Antenna analyzers are more appropriate. Option D (Frequency counter): Incorrect. A frequency counter measures signal frequency but doesn't measure antenna resonance or impedance. It just counts frequency.
知识点
Antenna analyzers, Antenna resonance, Impedance measurement, Antenna tuning
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.