What does the term 'signal attenuation' refer to in the context of directional couplers?

The term 'signal attenuation' in the context of directional couplers refers to the loss of signal power as it travels through a medium. In practical scenarios, as a signal travels through a coupler or any transmission medium, some portion of its power can be lost due to various factors such as resistance, dielectric losses, or radiation losses, which effectively reduces the signal's strength or amplitude over distance. This loss is a critical factor in designing and utilizing directional couplers since it impacts the efficiency and effectiveness of signal distribution. Attenuation is often quantified in decibels (dB) and is an important consideration in high-frequency applications to ensure that the received signal remains above a certain level for reliable communication.