Popular intermediate frequencies (IF) for microwave and radar receivers operating in the 1–10 GHz RF range are typically which of the following?

Introduction / Context:Microwave and radar receivers use down-conversion from gigahertz RF to a convenient IF where filtering and amplification are practical. Standardized IFs simplify filter design and system interoperability.

Given Data / Assumptions:

• RF range: 1–10 GHz (L-, S-, C-, X-bands).
• Need IF high enough to separate images yet low enough for high-performance filters.

Concept / Approach:

Common IFs for microwave superhets include ~30 MHz, ~60 MHz, and ~70 MHz (and their near variants). These strike a balance between image rejection, filter availability (crystal/SAW), and achievable IF gains.

Step-by-Step Solution:

Verification / Alternative check:

Radar/receiver literature and module catalogs list 30/60/70 MHz IF chains as industry staples.

Why Other Options Are Wrong:

• kHz IFs are far too low for modern microwave selectivity demands.
• GHz IFs defeat the purpose of down-conversion.
• 1.6/4.5/10.7 MHz are common in other contexts (e.g., 10.7 MHz for FM), not typical for microwave radar IF back-ends.

Common Pitfalls:

• Assuming FM broadcast IF (10.7 MHz) is universal; microwave systems prefer higher IFs.

Final Answer:

30, 60 and 70 MHz