Which ASR-11 beam is the normal radiation beam and is always used to transmit and receive?

The correct answer identifies the normal radiation beam utilized for transmitting and receiving in the ASR-11 radar system. The Low beam is specifically designed for standard operations, providing reliable coverage and optimal performance for air traffic control functions. It operates in a manner that ensures consistent communication with aircraft within its service area, facilitating effective surveillance and tracking.

In contrast, the other beam types, such as the L-beam, S-beam, and High beam, serve different purposes or conditions depending on environmental factors or specific operational needs. For example, the L-beam and S-beam may be employed for varying altitudes or specific radar performance scenarios, while the High beam is used for detecting aircraft at greater ranges or altitudes. However, they are not designated as the standard beam used for day-to-day transmission and reception. This distinction highlights why the Low beam is the normal beam in the ASR-11 system.