Which of the following best describes the typical frequency service for coax versus waveguides?

• A. Coax is used for lower to mid frequencies; waveguides are used for higher frequencies requiring lower loss and higher power
• B. Coax is used for higher frequencies; waveguides for lower frequencies
• C. Both are interchangeable with no performance difference
• D. Waveguides are smaller and cheaper than coax

Answer: (A)

At lower to mid frequencies, coaxial cables are favored because they’re flexible, easy to install, and cost-effective, with sufficient performance for those bands. As you move to higher frequencies, coax suffers more from attenuation and dielectric losses and can’t handle as much power, while waveguides—hollow metallic tubes—offer much lower loss per unit length and can carry higher power. That combination makes waveguides the better choice for high-frequency, high-power links, even though they’re bulkier and more expensive. So the description that coax handles lower to mid frequencies and waveguides handle higher frequencies with low loss and high power captures the practical trade-off. The other statements don’t fit the real-world performance: coax isn’t typically used primarily at the highest frequencies, saying there’s no performance difference ignores clear distinctions in loss and power handling, and waveguides aren’t smaller or cheaper than coax.