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

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

• A. It has more loss per foot
• B. It cannot be used for VHF or UHF antennas
• C. It requires special techniques to prevent water absorption
• D. It cannot be used at below freezing temperatures

Answer: (C)

The correct answer highlights a significant limitation of air core coaxial cable in comparison to foam or solid dielectric types. Air core coaxial cable is constructed without a dielectric material surrounding the inner conductor, which can lead to absorption of moisture when exposed to the environment. This moisture can negatively affect the cable's performance, especially in terms of attenuation and signal quality. In contrast, foam and solid dielectric coaxial cables are designed to provide better protection against environmental factors, including water absorption. These types of cables utilize materials that are inherently more resistant to moisture, thus ensuring more reliable performance over time, especially in varying weather conditions. The other options reflect inaccuracies or limitations that do not directly pertain to the core issue of moisture absorption in air core cable. For instance, air core coaxial cables can be used for VHF and UHF antennas, and while there may be performance considerations at certain temperatures, the primary disadvantage lies in its vulnerability to moisture, making option C the focus of concern.

The correct answer highlights a significant limitation of air core coaxial cable in comparison to foam or solid dielectric types. Air core coaxial cable is constructed without a dielectric material surrounding the inner conductor, which can lead to absorption of moisture when exposed to the environment. This moisture can negatively affect the cable's performance, especially in terms of attenuation and signal quality.

In contrast, foam and solid dielectric coaxial cables are designed to provide better protection against environmental factors, including water absorption. These types of cables utilize materials that are inherently more resistant to moisture, thus ensuring more reliable performance over time, especially in varying weather conditions.

The other options reflect inaccuracies or limitations that do not directly pertain to the core issue of moisture absorption in air core cable. For instance, air core coaxial cables can be used for VHF and UHF antennas, and while there may be performance considerations at certain temperatures, the primary disadvantage lies in its vulnerability to moisture, making option C the focus of concern.