What intermediate frequencies are usually used in radar receivers?

• A. 30 MHz or 60 MHz
• B. 100 Hz or 1 kHz
• C. 1 GHz
• D. 3 GHz

Answer: (D)

In radar receivers, the intermediate frequency is chosen to balance filter practicality, oscillator stability, and image rejection. For microwave radars, the front-end RF is in the GHz range, so converting the signal to an IF in the high-GHz region lets you use high-Q, compact filters and reliable local-oscillator sources without sacrificing performance. A few gigahertz as the IF provides good separation from the RF to suppress unwanted signals and LO leakage, while still allowing effective filtering and down-conversion stages downstream. Lower IF values, like tens of megahertz or kilohertz, would make filtering at microwave frequencies impractical and could worsen image rejection or require more complex, bulky filtering solutions. A 1 GHz IF is feasible but less common in practice for many microwave designs, whereas around 3 GHz hits a sweet spot that aligns with available high-frequency filter technology and stable, realizable oscillators.