Which factor is explicitly identified as a primary limiting factor for maximum range?

• A. Carrier Frequency
• B. Peak Power
• C. Receiver sensitivity with PRF as the primary limiting factor
• D. Pulse Repetition Rate

Answer: (C)

The key factor determining how far a radar can reliably see is the receiver’s ability to detect a weak return. The received echo must rise above the receiver’s noise floor by a sufficient amount (a minimum signal-to-noise ratio) for the system to say, with confidence, “we’ve found a target.” That threshold sets the practical maximum range: even if you could push more power or a sharper antenna, if the receiver can’t distinguish the faint echo from noise, the target remains unseen.

Pulse repetition frequency (PRF) comes into play by shaping how often you send pulses and how echoes are time-separated and processed. A higher PRF can improve detection through more frequent sampling or coherent averaging, but it also reduces the time window before the next pulse, which can cause echoes from distant targets to overlap with subsequent pulses. That overlap creates range-ambiguity problems, limiting how far out you can unambiguously identify targets. So PRF becomes a limiting factor in how far you can reliably assign echoes to the correct range bin, even though the fundamental detectability is still governed by receiver sensitivity.

In short, the ultimate ceiling on detectable range is set by the receiver’s sensitivity—what the system can recognize above the noise. PRF then acts as the primary parameter that constrains unambiguous range and processing, so the combination of receiver sensitivity with PRF defines the practical maximum range.