Which component is NOT part of the five components of the secondary radar system?

The five components of a secondary radar system typically include the antenna, transmitter, receiver, decoder, and display. The receiver is essential in a secondary radar system as it picks up the signals reflected back from transponders located on aircraft.

A crucial part of the secondary radar system is the decoder, which processes the information received from the transponder to extract valuable data such as the aircraft's identity and altitude. Furthermore, the display showcases this information to air traffic controllers, thus facilitating effective monitoring and management of air traffic.

While the antenna is also a vital element that emits and receives signals, the receiver plays a unique role in capturing those signals, making the absence of the receiver critical as the radar system would not be able to process information if it is missing. Therefore, identifying the receiver as a non-component in this context does not align with the operational components essential for a functional secondary radar system.