Photonics-Based RF Signal Amplitude, Frequency and Phase Controller for Frequency Diverse Array Radar Systems

Frequency diverse array (FDA) radar systems have gained significant attention due to their ability to generate range-angle dependent beampatterns, enabling improved target discrimination and enhanced sensing performance. Unlike conventional phased array radars that rely solely on phase steering, FDA radars introduce small frequency offsets across antenna elements to shape the transmit-receive beampattern in both space and range. However, practical implementation of FDA radars remains challenging due to the need for precise and flexible control of frequency offsets, phase shifts and amplitudes of RF signals. We propose and experimentally demonstrate photonics-based RF signal amplitude, frequency, and phase controllers for a quasi-monostatic FDA radar system that generates a dot-shaped transmit-receive beampattern. The system employs a compact microwave photonic structure that introduces arbitrary frequency offsets to an RF signal while providing continuous 0°-360° phase tuning and adjustable amplitude control, without the use of RF components. A corresponding photonic receiver architecture for processing the radar echo signal is also presented. Both the transmitter and receiver are designed to minimise the number of components, thereby improving the practicality and scalability of FDA radar implementation. Experimental results demonstrate frequency translation with over 30 dB spurious suppression of a 15 GHz RF signal. A full 0°-360° phase tuning range and 0-25 dB amplitude control of an RF signal to be transmitted and received by an FDA radar are also verified experimentally.