Superheterodyne receivers: What happens if the intermediate frequency (IF) lies within the receiver’s own tuning range?

Introduction / Context:
In superheterodyne radio receivers, the incoming radio frequency (RF) is mixed with a local oscillator (LO) to produce a fixed intermediate frequency (IF). This IF is then amplified and filtered for selectivity. Placing the IF within the receiver's own tuning range creates multiple interference and usability problems that designers try to avoid.

Given Data / Assumptions:

• Receiver uses superheterodyne architecture with a fixed IF (for example, 455 kHz in AM broadcast sets).
• The receiver's RF tuning range includes the IF itself.
• Standard mixer behavior produces sum and difference frequencies.

Concept / Approach:

If the IF lies inside the tunable RF band, the receiver can unintentionally tune to its own IF, and signals near the IF will interfere with normal operation. Beat notes (heterodyne whistles) and dead zones occur. Adjacent bands near the IF become unusable because any small leakage or LO harmonics can produce a loud tone or self-oscillation-like artifacts.

Step-by-Step Solution:

Verification / Alternative check:

Receiver design handbooks recommend choosing IF values outside the receiver's RF coverage band or adding front-end RF selectivity explicitly to avoid these issues.

Why Other Options Are Wrong:

• (a), (b), and (c) each describe real effects; the correct comprehensive choice is (d) All of the above.
• (e) None of the above contradicts known superheterodyne behavior.

Common Pitfalls:

• Confusing image-frequency problems with the distinct issue of IF being inside the tuning range; both are different but harmful.

Final Answer:

All of the above