Explanation: Waveguides are transmission lines designed to efficiently carry microwave signals. When bending a waveguide, it's crucial to make the bend gradual to avoid significant signal reflections, power loss, and mode conversion. For X-band frequencies (typically 8 to 12 GHz), the physical dimensions of standard rectangular waveguides (e.g., WR-90) are quite small, with the broad dimension ('a') being approximately 0.9 inches. To ensure low loss and good performance, the radius of any bend should be several times the broad dimension of the waveguide, or at least a significant fraction of a wavelength. A bend radius of two inches provides a sufficiently gradual curve for X-band waveguides, minimizing reflections and maintaining efficient power transfer. A radius smaller than two inches (like one inch) would be too sharp, leading to substantial signal degradation. While larger radii (three or six inches) would offer even lower losses, two inches is a practical minimum threshold that balances performance with physical space constraints for X-band applications. Therefore, the radius must be *greater than* two inches to meet this minimum.