Deep Dive: T9A07
The correct answer is A: Signal strength is reduced due to the shielding effect of the vehicle. A disadvantage of using a handheld VHF transceiver with a flexible antenna inside a vehicle is that signal strength is reduced due to the shielding effect of the vehicle. The vehicle's metal body acts like a Faraday cage, blocking and reflecting RF signals. This significantly reduces both transmit and receive performance. For amateur radio operators, this explains why mobile operation requires external antennas mounted outside the vehicle. Understanding vehicle shielding helps explain mobile antenna requirements.
Why Other Answers Are Wrong
Option B: Incorrect. The antenna bandwidth doesn't decrease due to vehicle shielding - bandwidth is an antenna characteristic, not affected by nearby metal. The issue is signal strength reduction. Option C: Incorrect. SWR might actually improve slightly due to vehicle ground effects, but signal strength is still reduced. The primary problem is shielding, not SWR. Option D: Incorrect. Since B and C are not correct, 'all of the above' cannot be correct. Signal strength reduction due to shielding is the main disadvantage.
Exam Tip
Handheld inside vehicle = reduced signal due to shielding. Think 'S'hielding = 'S'ignal 'S'trength reduced. Vehicle metal body blocks RF, reducing both transmit and receive. Bandwidth and SWR aren't the main issues - shielding is.
Memory Aid
Handheld inside vehicle = reduced signal due to shielding. Think 'S'hielding = 'S'ignal 'S'trength reduced. Vehicle metal body acts like Faraday cage, blocking RF. External antenna needed for mobile operation.
Real-World Example
You try using your handheld with its flexible antenna inside your car. The vehicle's metal body shields the antenna, blocking RF signals. Your transmit power is significantly reduced because the signal can't radiate effectively, and you can't receive weak signals because the vehicle blocks incoming RF. Mounting an external antenna on the roof solves this by getting the antenna outside the shielding vehicle body.
Source & Coverage
Question Pool: 2022-2026 Question Pool
Subelement: T9A
Reference: 2022-2026 Question Pool · T9 - Antennas and feed lines
Key Concepts
Verified Content
Question from the official FCC Technician Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the T9A topic.