What is a disadvantage of using a handheld VHF transceiver with a flexible antenna inside a vehicle?
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.
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 Application
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.
Key Concepts
Why Other Options 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.
题目解析
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.
考试技巧
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.
记忆口诀
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.
实际应用示例
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.
错误选项分析
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.
知识点
Vehicle shielding, Mobile operation, Antenna placement, RF shielding
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.