Instantaneous Microwave Frequency Measurement Using a Photonic Microwave Filter With an Infinite Impulse Response

A photonic technique for instantaneous microwave frequency measurement is proposed. In the proposed technique, a photonic microwave filter having a monotonic frequency response with the magnitude varying from positive infinity to negative infinity on a log scale, is constructed by cascading two photonic microwave filters with one having an infinite impulse response and the other having a finite impulse response. For a single-frequency microwave signal with a normalized magnitude, a unique relationship between the output response and the input frequency is established. Since the response extends from positive to negative infinity, for a given measurement range, a significantly increased measurement resolution is achieved. The proposed technique is verified by an experiment.