Deep Dive: T7C02
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.
Why Other Answers 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.
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 Example
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.
Source & Coverage
Question Pool: 2022-2026 Question Pool
Subelement: T7C
Reference: 2022-2026 Question Pool · T7 - Practical circuits
Key Concepts
Verified Content
Question from the official FCC Technician Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the T7C topic.