Which of the following structures is NOT commonly used to support telecommunications antennas?

In the context of telecommunications infrastructure, a spur is not typically recognized as a standard structure used for supporting antennas. The term "spur" often refers to a secondary or subsidiary structure or branch that does not serve the primary purpose of supporting telecommunications antennas.

On the other hand, self-supporting towers, guyed towers, and monopoles are all well-established structures designed specifically for supporting telecommunications antennas. Self-supporting towers are designed to stand by themselves, relying on their design and structural integrity. Guyed towers are supported by guy wires that anchor the structure to the ground, providing stability and allowing for greater height and load-bearing capacity. Monopoles are single, tall structures that also serve as effective supports for antennas, offering a smaller footprint compared to other types of towers.

Understanding these different structures and their specific roles in telecommunications can highlight the unique nature of a spur as not being a conventional choice for antenna support.