High power input protection for signal measurement devices

A protection device usable with a signal measurement device to limit power level of radio frequency (RF) signals propagated to the signal measurement device can include a direct current (DC) block capacitor, a variable impedance limiter, and a detector. The variable impedance limiter includes a PIN diode electrically connected with a primary signal path of the protection device along a limiter signal path. The detector includes a Schottky detector diode and a limiting resistor electrically connected with the primary signal path along a detector signal path. The detector is configured to generate a DC bias current to adjust resistance of the variable impedance limiter in response to an RF signal.