A Simple Approach for Simultaneous Measurement of Instantaneous Frequency and Angle of Arrival

A microwave photonic instantaneous frequency and angle of arrival (AOA) measurement method based on a Sagnac loop is proposed and demonstrated in this article. By establishing a monotonic relationship between the phase difference and the dc amplitude, an amplitude comparison function (ACF) is constructed to achieve AOA measurement. Meanwhile, the instantaneous frequency measurement (IFM) is achieved by introducing optical delay. By adjusting the optical delay, the scheme can not only tune the frequency measurement range but also increase the measurement accuracy. The experiment results prove that the phase difference error of the AOA measurement is less than 1°, and the IFM measurement error in the frequency range of 0.5-36 GHz is ±0.2 GHz. The scheme has the characteristics of multifunction, simple structure, and large bandwidth, it has a great competitive advantage in future electronic applications.