Microwave photonic radar warning receiver: airborne antenna over fiber optic

Abstract

Electronic warfare had great importance mainly in the Second World War. Radar was one of the greatest inventions in the area at that time, reinventing the way war was viewed until then. Nowadays, modern combat aircraft has sophisticated warfare systems. One of them is known as radar warning receiver (RWR), responsible for alerting pilots to possible radar detection and guiding the direction in which it is being radiated. Technological innovations allowed the interaction of the microwave and optoelectronics area, leading to an area known as microwave photonics (MWP). This article presents a photonic link to replace the copper cables used by RWR systems, applying photonic technology in order to improve performance and benefit from the intrinsic characteristics that optical fiber offers to the system, offering a totally passive remote system, in which only one phase modulator is connected to the RWR antenna. The results obtained for a totally photonic link by experiment were satisfactory. As expected, a gain above the unit was obtained. However, the observed noise figure was higher than expected, which ended up resulting in a lower signal noise ratio.