The invention relates to a frequency-converting sensor for providing at least a radio frequency signal parameter, especially an electrical power value. The sensor comprises an analog receiving section for converting an input signal into corresponding I/Q-components using a local oscillator frequency, an analog to digital converting unit for converting the corresponding analog I/Q-values into digital I/Q-values and a digital processing unit. The digital processing unit comprises an adjustable filtering unit for selecting a frequency band of the RF input signal and a calculating unit for calculating at least an electrical power value from the I/Q-values of the selected frequency band. The invention furthermore relates to a system for analyzing radio frequency input signal parameters, wherein the system incorporates a device under test, which generates the radio frequency signal, the inventive sensor, and a displaying device.