In addition to serving as directional radiators, what other purpose do horn radiators serve?

Horn radiators serve multiple functions in addition to their primary role as directional radiators. One of their significant purposes is functioning as waveguide impedance matching devices. In radio frequency applications, the transition from a coiled transmission line to free space can lead to impedance mismatches that result in signal loss. Horn radiators effectively manage these mismatches by providing a smooth transition in impedance, allowing for efficient energy transfer from the waveguide into free space.

The shape of the horn is designed to gradually expand the wavefront of the electromagnetic waves, which minimizes reflection and maximizes the transmission of energy. This impedance transformation helps maintain a strong signal and improves the overall performance of the antenna system.

In contrast, the other options focus on different functions that horns do not primarily serve. While antenna scanning or signal amplification and frequency modulation relate to different aspects of signal processing and communication, they do not directly align with the physical and practical characteristics of horn radiators.