ARRL Technician Practice Exam

What is a disadvantage of air core coaxial cable when compared to foam or solid dielectric types?

1. It requires special techniques to prevent water absorption

2. It is more expensive to manufacture

3. It has a higher signal loss

4. It is more difficult to work with

The correct answer is: It requires special techniques to prevent water absorption

The chosen answer highlights a significant disadvantage of air core coaxial cable: its susceptibility to water absorption, which necessitates special techniques to mitigate this issue. Air core coaxial cable is designed with a dielectric that is primarily air, which can leave it vulnerable to moisture infiltration. When water enters the cable, it can degrade performance by increasing signal attenuation and can lead to the likelihood of damage over time. In contrast, foam or solid dielectric coaxial cables are generally designed to be more resistant to moisture. These materials do not allow for easy water intrusion, which in turn helps maintain signal integrity and overall durability. Therefore, the need for special measures to manage moisture with air core coaxial cable marks its primary disadvantage when compared to foam or solid dielectric options. The other options focus on different facets but do not capture the critical concern of moisture absorption. For example, while air core cables may have different cost dynamics, the mention of expense does not directly correlate with the physical vulnerabilities inherent to the design. Similarly, signal loss characteristics are also a prevalent aspect, but not specifically linked to the moisture issue like the first option. Lastly, difficulty in handling is more a matter of user skill and practice rather than an inherent disadvantage of the air core design itself. Thus,