Microwave angle-of-arrival measurement utilizing photonic real-time Fourier transformation

Abstract

A microwave angle-of-arrival (AOA) measurement system based on the photonic real-time Fourier transformation (RTFT) is proposed and demonstrated. In the proposed system, photonic RTFT is implemented utilizing the temporal-spectrum convolution system, which is composed by an optical pulse source, an electro-optical modulator and a pair of dispersive elements with complementary dispersion values. The time delay of the linearly frequency-modulated (LFM) signals can be obtained, which are used to calculate the time-difference-of arrival (TDOA) and the corresponding AOA. A proof-ofconcept experiment is taken. The AOA measurement range from 25° to 155° is achieved with a measurement error of less than 3.4°. In this scheme, the problem of phase ambiguity in traditional AOA measurement systems is overcome.