Which component in a RADAR receiver is responsible for mixing signals?

The correct answer, the crystal detector, acts as the mixer in a RADAR receiver system. Its primary function is to combine the received radio frequency (RF) signals with a locally generated signal in order to produce an intermediate frequency (IF) signal. This mixing process is essential because it allows the system to convert high-frequency signals into a lower frequency that is easier to process and analyze.

In RADAR systems, the signals received from targets are often at very high frequencies. The mixing action performed by the crystal detector effectively facilitates demodulation, enabling the extraction of useful information such as the distance to, and speed of, the target. This allows for improved target tracking and detection capabilities within the RADAR.

Other components listed, while important in the overall RADAR system, do not serve the mixing function. The discriminator, for example, is typically used for frequency modulation demodulation, while the IF amplifier amplifies the intermediate frequency signal after it has been mixed. The Klystron is a type of microwave oscillator or amplifier and does not engage in mixing signals.