Question 6A473

In a superheterodyne receiver, the image frequency is an undesired input signal that, when mixed with the local oscillator (LO), produces the same intermediate frequency (IF) as the desired signal. The image frequency is always separated from the desired signal frequency by twice the IF frequency ($F_{image} = F_{signal} \pm 2 \times F_{IF}$). A higher IF frequency pushes the image frequency further away from the desired signal. This increased separation makes it much easier for the receiver's RF pre-selector filter (the tuned circuit before the mixer) to attenuate the image frequency. By effectively filtering out the image, the receiver's susceptibility to this unwanted signal is *reduced*. Therefore, a high IF improves image frequency rejection.