Photonics for Radars Operating on Multiple Coherent Bands

The introduction of photonics in microwave systems
is setting new paradigms in radar architectures, providing new features
potentially improving the surveillance effectiveness. In particular,
photonics is enabling a new generation of the multiband
radars able to manage multiple coherent radar signals at different
frequencies simultaneously, with high and frequency-independent
quality, enabling multispectral imaging for advanced surveillance
systems. In fact, thanks to its high stability and huge bandwidth,
photonics matches the urgent requirements of the performance
and flexibility of the next-generation software-defined radar architectures,
and it guarantees system compactness, thanks to the
use of a single shared transceiver for multiband operations and
to the potentials for photonic integration, which also promises reduced
power consumption. In this paper, we present the first field
trial, in a maritime scenario, of a fully coherent multiband radar
enabled by the use of photonics. The paper reviews the basic concepts
exploited for the photonic generation and the detection of the
radar signals, and describes the extension to the multiband operation.
We present details on the implementation and testing of a
dual-band coherent radar system, discussing the potentials for a
software-defined radio approach. Moreover, the results obtained
after a simple digital data fusion are discussed, highlighting the
capability of the coherent photonics-based multiband radars in
exploiting the extended observation bandwidth for improving the
system detection resolution with minimum computational costs.