What are intermodulation products and how do they affect receiver performance?

• A. Linear amplification of signals with no distortion
• B. Phase noise causing jitter in the oscillator
• C. Nonlinear mixing of signals produces sum/difference frequencies causing interference
• D. Antenna misalignment causing interference

Answer: (C)

Intermodulation products happen when multiple RF signals pass through a non-linear element, such as an amplifier or mixer. The nonlinearity mixes the signals and creates new frequencies at the sums and differences of the original frequencies. If any of these new frequencies fall inside the receiver’s passband, they show up as interference, reducing the receiver’s sensitivity and dynamic range and potentially causing false signals or desense.

Think of it like this: in a perfectly linear system, signals just pass through without creating anything new. But real devices have some nonlinearity, so strong nearby signals can “creep” into the channel by mixing and producing extra tones. The other described issues—phase noise causing oscillator jitter or antenna misalignment causing interference—do not involve this nonlinear mixing process and thus are not about intermodulation products.