Amplifier Headroom / P1dB Compression Calculator
An LNA's noise figure and gain specs assume it's operating linearly. A strong nearby signal — an FM broadcast tower, a radar test bench, a jammer — can push it into compression even if your wanted signal is weak. This tool sums everything hitting the LNA's input, applies its gain, and checks the result against the amplifier's P1dB spec.
P1dB isn't a hard ceiling — it's the point where gain has already dropped 1 dB from its linear value. Distortion is present, and rising, well before you get there, and gets meaningfully worse past it. Treat 0 dB headroom as "already degraded," not "still fine." For distortion from two closely-spaced strong signals specifically (intermodulation products landing on your wanted frequency), that's a third-order intercept (IP3) question, not a P1dB one — use the IP3/dynamic range calculator for that case.
Need more headroom? A bandpass or notch filter ahead of the LNA removes the interferer entirely instead of just tolerating it — usually the bigger win over choosing a higher P1dB amplifier.